Piston Pumps Displacement Pressure Cutoff Adjustments May 26 2020

it says going live your live and the pump out that will fall [Music] got some gluing syringes all of these are not the kind for taking your medicine but yeah for getting glue some adhesive where it needs to go actually we kind of use these around the shop here sometimes to squirt fluid in and out of different passages just to see where things connect up and yeah what does a syringe like this draw it back suck in a charge of fluid push it forward eject what does a syringe like this have in common with a piston pump right it's a very similar concept in fact you may have seen some of our 3d videos where piston pumps are likened to a group of these syringes spinning around on an axis and and sucking in some fluid and then discharging again at a different point in the rotation right some people like to call the axial piston pump a swashplate pump right there's the swash plate and there's the piston slip or pads at the back there and yeah we've kind of cut away a good chunk of the cylinder barrel here you don't usually see so much of the piston so we've cut away quite a bit to make it a little easier to understand what's going on maximum displacement off stroke right so there we go a couple of basic concepts already coming into play there right in fact that'll be our pop quiz question today because you've got choices right you could have chosen a gear pump you could choose a vein pump before your hydraulic machine perhaps a few other variations on that so why use a piston pump what's the main advantage or what's one of the key advantages of using a variable displacement axial piston pump that'll be our our pop quiz why use a swash plate type of pump hello this is Carl from lunchbox sessions comm welcome let's have some fun today with axial piston pumps variable displacement pumps and we'll also spend some time making adjustments to the pressure compensator and the maximum volume stop sometimes called Q max and as always let's keep in mind the power and the force behind hydraulics potentially injurious and lethal force is there so what we do today in our short hour together is not to be considered as comprehensive training for making pump or live power unit adjustments make sure that you take the training required in your jurisdiction from whatever Institute is necessary to certify you for work on hydraulic systems and follow all precautions necessary to keep yourself safe from the hazards all hydraulic systems on our lunch box sessions dot-com / live page you'll notice that there are some data sheets for you to download and those data sheets cover off on the three main hydraulic pumps that we'll be working with today over here behind me is a nachi america pump there's an oil gear and also a Bosch Rexroth so whether we have time to open those particular files or not I don't know but for you if you're interested in the exact pump models that we worked with during our time today those data sheets are there for you to download and explore more of the specifics that go with those pumps our humble thanks to you for all of the wonderful messages that you've sent since our last YouTube live so many of you sent in encouraging emails and messages by LinkedIn and left remarks also on our YouTube that's fantastic thank you very much for that just slowly getting used to after this is our fourth now I guess and so I'm I'm slowly getting used to our live broadcasts and it's just great to be with you again today welcome from Bulgaria Turkey Indonesia somebody here from planet earth apparently on the list Saudi Arabia Bahrain Holland and that's tool time Chris over there in Netherlands Thank You Canada Poland Morocco India Philippines the okay South Africa just joined in thanks for joining us today yeah it's fun for us to be able to share during this time our twenty plus years of working directly in heavy industry and the things we've learned in hydraulics and I hope our time together is of benefit to you as well you'll probably notice that there is a live chat where you can interact with us and if you're not already aware you'll have to be logged in to your YouTube account or other Google services in order to be able to use that live chat and send us questions during the during the broadcast feel free to do that and we'll do our best if your questions during the chat have to do with the content of today's presentation we'll do our best to get to those if you have other questions about our services other questions about hydraulics what have you feel free to email us info at lunch box sessions comm and also another great way to interact is to find me on linkedin carl dyke industrial teacher i should be pretty easy to track down send me an invitation to link and we can also chat back and forth that way i enjoy that a lot too sometimes I get a little bit behind in some of my interactions with you but keep reminding me and I'm sure over time I'll catch up I do enjoy chatting about hydraulics and your various mechanical maintenance issues wherever you are on planet Earth okay this is our fourth live broadcast in a series of eight they'll be two more in June the next one is on particle contamination there's one near the end of June on servo servo valves of servo cylinders with tempo Sonic's in them and what-have-you so we'll do that one in late June and then there's two more also one more in July one more in August keep track of our schedule and our topics at lunch box sessions comm slash live ok a shout out to my great friends at fluid power worldcom fluid power world is your resource on components it's a great place to go to learn about machinery design and the latest in system engineering keep track also at the events linked on fluid power world there were scheduled for this year some live conferences perhaps that's gotten a little more complicated but keep up with the events tab there and there may well be a virtual hydraulics conference across the fall and we'll see how that goes I'd love to meet you at the conference great learning opportunities and create opportunities for us to interact today's session is sponsored by oil gear for nearly 100 years oil gear has been engineering industrial products for extremely challenging environments from the depths of subsea work to moon exploration pulp mill Bale presses steering pumps on mining haul trucks and many other heavy-duty continuous run applications feature the reliability of oil gear engineering welcome also to Brazil and Russia and Mexico thanks for joining us today all right so as we get underway talking about piston pumps and specifically a couple of the adjustments that show up quite commonly on a pump controller as you know I often like to show you some of the photographs from installations that we've encountered in our travels so a collection of photos over the years from various different industries that we come and go from you'll probably recognize this particular pump has a Rexroth a 10 series and what you notice of course is that there appears to be two adjustments hoping everyone can see my little white magnifying glass they're highlighting various controls and of course if that second controller out from the pump body has no control hose hooked up to it and external control hose that would come back then in all likelihood you've only got the single adjustment of pressure compensate and this one here often the load sense or sometimes referred to as flow compensator has been right down and knocked out of the control scheme and there's only a pressure compensator oh oh I think there's a pump controller under there somewhere some pumps get a little bit dirty in operating environments here's another so we're looking from the shaft end but if we look towards the cap end of the pump we'll see a cylindrical protrusion off to one side yeah sometimes it sticks out off to the side and we can see an adjustment there single adjustment pressure compensator and we'll have to look in a moment to see what does it mean to to adjust a pressure compensator here's another style oil gear with transverse types of controllers across the top of the pump body and that's another way of arranging and you could see a couple of adjustments one on one side sticking out and one from the other okay so a couple of adjustments there and we'll get into those and what they mean in a moment here again is fairly simple pressure compensated piston pump with a single adjustment pointed towards the shaft end okay what are we going here mobile equipment some caterpillar equipment I believe this one's from a grater and again we see the two controllers sticking outside of the pump body pressure compensator being the larger one or pressure cutoff we're gonna talk about that that's limiting a maximum system pressure watching out for that very tippy top pressure yes there may be a relief valve set another 300 psi perhaps higher but that's for just in case this this pressure compensator will be the main top pressure regulator here is that load sense or flow compensating that won't be the topic of today's that'll be for later in August when we come back to look at load sense and if you're interested in margin pressure low standby pressure those types of things join us in August for that one but you may have that control hose coming in and so you will have to look into your machinery maintenance and adjustment notes to find out what it is you need to do to knock out the effect of the lower flow compensator load sense compensator in order to allow you to adjust the pressure compensator or join us in August and we'll cover that one at that point here we are again basic Rexroth a10 type of installation with nothing hooked up to the load sense so just often ship together as a package and only single pressure compensator in action in that particular scenario all right so let's move on and start thinking about what is inside of a piston pump so a few movies from our website here let me bring up the first one let me just pause and I'm just gonna go back to the beginning there alright so I mentioned syringes before there they are spinning between the spokes of a bicycle wheel I guess we made the world's simplest pump and you could see those syringes drawing back on the inlet side drawing in oil through the larger kidney in the valve plate sucking in a charge but then but due to the angle of the swash plate those syringes push forward again and eject hydraulic oil out on the outlet and hence the need for that angled swash plate so that we can understand how it is that the syringe is maybe there Pistons actually in reality but how those syringes draw in a charge of fluid and push back out again and eject fluid can but really it's not so much about syringes but let's think about that device called the swash plate here's a simple one where we've left the handle in play not very common to have a handle oh yeah okay so what we've done there's changed the angle to half so now our pumping rate is slower because our Pistons only draw back so far and only discharge a what happened there I think our swash plate went to the perfectly vertical position and now our Pistons no longer draw in fluid nor do the eject fluid one could say that the pump is off stroke okay and yet the rotating group is still spinning if there is a shaft from a prime mover so that's a fairly basic idea of what piston pumping action is all about we've got an additional clips on our lunch box sessions calm if you want to see more of that okay and now let's do a little bit of thinking here about what's happening in the piston pump adjustments that we want to speak about if you come to a condition in a hydraulic system where the cylinder loading or perhaps the hydraulic motors are overloaded or perhaps perhaps we're in a condition where directional valves have closed and blocked the primary flow of pump fluid through the system any of those conditions basically are an example of an overload condition where the pressure would run away too much too high a level and traditionally of course with a gear pump or a vane pump one would rely on the relief valve to take all of the pumps flow back to tank but it would do so at a top pressure value and there's some disadvantages to that we'll get to that in a minute enter the piston pump which allows us to have a controller for that swashplate and say hey if we get to the point where the system pressure is too high perhaps we could just reduce the the flow from the pump to near zero and then hold the outlet pressure with just a tiny tip back on stroke of that swash plate and be ready for a time when the height when the directional valves open once again be ready for a time when the hydraulic cylinder isn't overloaded and then the pump could come back on stroke automatically and that's one of the jobs that is covered off by the pumps pressure compensator so here we go let's have a look at the scenario where on the outlet of our pump we've got a pressure gage then a needle valve just so that we can shut in the pumps flow for most of you that will just be the moment when your directional valves close you could also think of it as as a moment though also when your hydraulic cylinders or perhaps your hydraulic motors are overloaded so we'll close in the needle valve will see our flow meter drop to zero beyond that needle valve and we'll see our pumps maximum pressure value come to a high-value as that needle valve is closed and let's see what happens our pump has gone to a zero stroke condition it's already off stroke well how was that achieved okay so perhaps a little out of sequence but let's think about it it's very hard to to demonstrate it perfectly in that a lot of these things happen almost instantaneously certainly within a small fraction of a second so if we cut open to that pressure compensator that we saw in some of my photographs as we were getting underway what we will see is a very small spool only the diameter of a pencil working against a fairly stiff spring that was adjusted by you if you're the maintenance technician to a certain pressure and what's happening is pumps outlet pressure is available and as the pressure gets high enough also acting on the end through a drilled out board out passage in this case driving a spool towards the spring and uncovering a passage that drops down into the control piston and you'll see that control piston again from the side in just a moment and perhaps we exaggerate and move that pressure compensate spool a little too far compared to how much motion it actually is under but allows you to appreciate the action of what that pressure comp spool is up to what it is doing is working here we go let's let's increase our pressure here let's talk about that a little bit so if we dial that allen key clockwise we come up to a higher pressure and what can we say has happened well it's just made it a little bit more difficult for that pump outlet pressure to shift that spool against that stiffer spring and now our outlet pressure on the pump will come to even a higher level before the control piston that you see here the large control piston D strokes the pump towards zero and anytime that pump gets to that zero angle due to internal leakage in the pump that pressure will start to fall a little bit then the spring and the compensator will close up the pressure compensator once again and a device called a bias spring or a bias piston down at the bottom in this pump we'll try to drive that swash plate back on stroke there's a bias to this basic pressure compensated pump that says hey I'd like to go back on stroke to full production if I could okay so that's the spring there at the bottom which in this case also includes a piston there we are back on stroke it's not a very steep angle the large majority of pressure compensated piston pumps don't tip that swash plate too far past 20 degrees there's the odd one at up to 22 degrees some very heavy-duty pumps this angle is only as much as 15 degrees so it doesn't look like all that much when you see through from the side okay a couple of other adjustments that you may or may not have on your pump this one is called the maximum volume stops sometimes refer to as Q maximum Q a common letter for describing flow rate and this one is adjusted when the when the flow it has an easy unrestricted path through your system no pressure loading and if we dial that hex key clockwise basically what'll happen is we prevent that pump swash plate from ever reaching that 20 degree angle perhaps we're now at only 17 degrees angle or 15 degrees angle and perhaps if we keep turning that hex key a little bit further perhaps we could reduce this pump here we go to only half of its original size perhaps now we are pumping only at half of the gallons per minute that the pump would be at when that maximum volume stop Q max had been backed all the way out again that particular adjustment is made when there is a full flow path for oil from your piston pump throughout the hydraulic system with very little to no restriction at all okay so a basic introduction to a couple of adjustments that are commonly made with pressure compensated pumps you may have on your pump an additional adjustment but called the called the minimum volume stop and we'll talk about that one a little bit later alright let's think a bit more about the adjustments by working with some simulations in the fixed and variable displacement pumps session on lunchbox sessions scrolling down past the lessons and the video some exciting new videos that will catch up with later in our session and let's go down to our key simulations where you can practice making adjustments to piston pumps in a cutaway scenario so as that simulation opens up what you will notice of course is that we're looking at the cylinder barrel in cutaway form and you must use your imagination to understand that the cylinder barrel with its pistons is still spinning even though you're looking at the cutaway in 2d where that's not as easy to show so looking over to the left here you see a bit of a 3d mimic that we've left there to remind you that the shaft is still turning the prime mover is still running and that cylinder barrel is still spinning so given that reality given the fact that in this case we don't have a bias piston many pumps are situated like this where there's only a bias spring and that bias spring tries to always push that pump to the maximum displacement by getting that swash plate to the maximum angle whatever it happens to be and you'll see as I'm hovering over various components in this pump that if you look to the symbol in the upper right corner of the screen some of those components are also lighting up to help you understand how to read the schematic symbol all right so our pump is on full on full stroke it's displacing according to a flow meter further down here on the right on the pumps outlet line we're displacing 10 gallons per minute our pump swashplate is at its maximum angle and it says our outlet pressure is a mere 100 psi pressure that doesn't sound like too much to me for a hydraulic system and if I said hey maybe our pump pressure compensator shouldn't shouldn't be at that level or perhaps there should be a different pressure perhaps set it to 700 and if I went over here to the controls on the right-hand side of the screen and I started moving them around and perhaps someone would argue that now I'm set to let's set it to around 750 somewhere close to that there we are set at 750 you might say hey how do you know that well in this case only magic text here above the simulation so that's not realistic as you know any time you make an adjustment to a pressure control in a hydraulic system a pressure gauge should have followed your every move and in this case ours our outlet pressure didn't change at all we were not in the right system State for changing the value of the pressure compensator were we what state do we need to be in to adjust the pressure compensator that's right we need to have our flow out from the outlet of the pump blind it out in order to take that pump into the condition of triggering that pressure compensator okay so here's that pressure compensator that little spool okay and the pressure let's just be clear that the servo pressure that operates the control piston to D stroke the pump that comes from the pumps outlet and pump manufacturers have a variety of clever ways of taking that outlet pressure through some passages often in the cap end of the pump and routing it up into that pressure compensator to make it available so that when the compensator shifts you'll have a source of pressure to fill up a control piston a hydraulic cylinder of a sort in order to D stroke that pump so yes we were not in the right state for making adjustments to the pressure compensator if you make a few turns with a wrench and a gauge doesn't follow you probably something wrong with your procedure or something went wrong with the control put it back so keep track of how many wrench turns that was for safety sake let's put it back and start back to where we were and now very carefully we're going to close in and block out blind out the flow of the pump I'm just closing in the needle valve over on the right hand side of the screen for many of you that will just be returning your directional valves into the neutral state and making sure that they stay there if they are blocked pport directional valves as they commonly are with the use of a pressure compensated pump so there we are our system is blinded and our sorry our pumps flow has been blinded out you'll notice that our flow meter indicates we've dropped down to zero flow rate and now we see our pressure gauge and if it's a very fine resolution pressure gauge we might see a tiny variance if we could detect it and that might be due to what the pump swashplate is up to and other points of internal leakage on most pressure gauges you would not see the needle moving at all all right so if we want to make an adjustment if 500 psi is not the correct maximum pressure setting to support functions of the hydraulic system if the manufacturer of the hydraulic system require perhaps that it be set at 750 we now simply need to very carefully turn and now our pressure gauge should be following our every turn of the wrench and it most certainly is the pressure on the pumps outlet gauge is following the turns of the wrench that's a good sign perhaps we were supposed to be set at 750 psi and we've arrived at that point and what you see the pump doing what happens what really changes as we dial up that pressure compensator setting we merely increase the tension of a spring making it a little harder to move that spool waiting for a little bit more of a buildup in the outlet pressure before that device triggers and starts to move the pump off stroke does it change a lot what you see the swashplate doing when you are in the cutoff position pressure cutoff by the way is another PC oh there's another typical three-letter acronym that often shows up for the pressure compensate function P Oh our pressure override it seems like everything in hydraulics has three names I didn't make up any of them they are what we read when we read various different machinery Yul's from from different manufacturers but make sure you understand the definitions of those types of terms for the machine you're working on as per the manufacturer's manual all right what changes simply is that the that the bias spring is allowed to try and get those pistons to punch just a little harder against that outlet oil when it takes a little bit higher pressure to trigger that compensator due to the higher tension on the spring doesn't change the action of the swashplate all that much as you know hydraulic fluid is not that compressible it is slightly but pretty hard to detect a change in the swashplate position just by dialing that spring it's very subtle all right so we're set to 750 psi and we're in the right state for having made that adjustment if we want to make that other adjustment that we were going to cover in today's session which is the maximum volume stop that one's down here and you could see right now that the maximum volume stop a threaded rod coming in through the center of our control piston it's not even touching so probably this is not a good time to adjust what the maximum volume here I'll play around with that why would we do this why would we try to adjust the maximum volume stop when clearly you can see the threaded rod doesn't touch the control piston clearly nothing is changing on the output flow meter so we must be in the wrong state for this adjustment system state the state we need for our hydraulic system is to have a free and easy flow path so I'm going to open that needle valve back up and away we go our flow meter registers once again the maximum flow possible for this pump due to very low restriction to the system perhaps we're circulating right back to tank perhaps only through a return filter not sure okay it's off to the rate somewhere the rest of the system but now we see our swash plate is sitting with the control piston against that threaded rod the maximum volume stop and now is a good time to make that adjustment perhaps ten gallons per minute is going to spin a hydraulic motor too fast have said hydraulic motors turning a fan on on a system for for cooling liquids hydraulic oil engine coolant who knows and perhaps the spin rate of that fan motor will be too high or perhaps this pump is oversized for future expansion and right now perhaps it's only supposed to run at 8 gallons a minute you will need a flow meter this is where pressure gauges don't help you much you need a flow meter in place so that that yellow black object in this case is one style of a flow meter that might be in use and what I have done by adjusting that maximum volume stop usually clockwise on most pumps to reduce the volume setting okay but check check your pump data sheets to find out which direction to turn and if possible read the manufacturer's instructions to find out how much reduction in flow you should expect for every quarter turn or full turn and learn about your pumps data sheets are so important okay so we're altering the flow rate of the pump but that has no impact on the maximum pressure nothing noticeable for the function we're carrying out right now okay eight gallons a minute there you go maximum so we've prevented that swash bleed from hitting the 20 degree angle we've stepped it back a short amount and we've made those two adjustments that I said we were going to make in today's session we're just gonna have a quick look at a few other simulations briefly and then I'm going to answer the chat questions that you may have so far so the second simulation that we're going to get into here it's just to remind ourselves that in many a case pressure compensated pump on the outlet in many cases often will still include a relief valve okay there is the odd symbol that I'm sorry there's the odd hydraulic system that we encounter does not have the relief valve teed in to the pumps outlet line right near the pumps outlet port but the vast majority of them do and in many a case that relief valve is there in case of a system pressure spike coming back against the pump the relief valve is typically the faster acting device the pump takes just a little bit long it all happens in a fraction of a second but the relief valve may be faster and then some also argue that due to the small diameter of a compensator spool that it is perhaps the easier device to get stuck with contaminants and so then the relief valve is perhaps a backup begs the question as to how much redundancy one might need then in that case but if you have the relief valve there then the manufacturer of the pump or perhaps the manufacturer of the hydraulic system overall will specify that that relief valve has to be set higher than the pumps pressure compensator and typically those ranges for the relief valve higher in the pumps pressure compensator can run anywhere from 150 psi higher all the way up to 400 psi higher than the setting of the pumps compensator okay there's a number of ways to approach this but for the uninitiated and for those who want to be most careful with this process if if you are quite sure that relief valve and pressure compensator have been moved out of the original setting might be to make the beginning adjustments or to make the beginning of this process with the power unit shut off so I'm going to shut down that pump and I'm going to turn the pressure compensator all the way and tighten that spring up so that the compensator will not react the relief valve I'm going to make sure that it's all the way back out to its lowest possible setting so when we start up and we'll assume that we're gonna start up against blocked P ports in your directional valves that would be common and so I'm going to close my needle valve to simulate the idea that you're working with a closed Center hydraulic system P ports at your directional valves are blocked okay which may may very well be the case so my relief valve is backed out my pressure compensator is tightened down and now when I start up my pump once again follow all of the lockout procedures that you must use in your jurisdiction of course we're moving quickly through simple simulations at this point all of our flow is over the relief valve which means we really don't have a variable displacement pump we don't have pressure compensated function right now remember we tighten down that compensator all the way okay so let's turn that relief valve setting to the required value you'd find that in your machinery manufacturers adjustment notes perhaps on the schematic that's where we like to find that in this case we'll say the relief valve is supposed to be set perhaps to 1,200 notice that a pressure gauge is following my every move so therefore my process for adjustment is working it's correct you are only setting a system relief valve when all of the pumps flow is passing through that relief so we're set at 1200 and without wasting too much time one now wants to get the wrench the hex key on that compensator and start backing it down because as you know oil over the relief valve for any prolonged period of time it's going to cause some serious heating so moving over the compensator and turning counterclockwise in this case it might take a few turns before the system starts to react and the pressure gauge starts to keep up with your every wrench turn counterclockwise and so perhaps our in this case we'll say our pressure compensator was supposed to be set 200 psi lower than the relief valve and now we have that setting we know that our relief valve is 200 psi higher than what's on the pumps pressure compensator ah another really good thing for us to notice before we move off of the simulations which will do shortly is to notice the case streamline the case drain line is not optional on a piston pump it is that critical third hose that is always there and during the case is so important because there is internal leakage there are a number of clearances where there may be small amounts of leakage passing between parts but also important to remember that if the compensator is active if that spool is shuttling back and forth and yes we move that spool farther than it does in reality helps us understand its directional functioning what you will notice is that there's actually what one could argue is controller exhaust a small amount of fluid with every punch back and forth that needs to be drained out of that active device so there it is we also noticed that when the control piston gets to its maximum length just so that we don't go past zero degrees on the swashplate just so that we don't crack this pump in half there may be on the control piston a relief orifice limiting how far that control piston can travel and you may notice a sudden surge in case drain flow as that orifice is uncovered and so that's a reason why you may see a sudden spike in case drain flow if you're measuring it and we'll talk about that some more in a moment all right so that's enough just to draw attention to the relief valve because we won't do that live relief valve adjustment on the power units that we've got here today we've done it in simulation form okay and now one last simulation before we answer today's pop quiz answer question and so let's just go back and look at simpler scenarios why such a fancy piston pump with all these controllers couldn't one just use a gear pump and a relief valve most certainly you certainly can but if you spend any amount of time pumping that gear pump over relief valve which doesn't accomplish much for motion control useful work is not happening when you're pumping over the relief valve you're simply converting your input energy into heat and oh well there's the issue it's a waste right so in this case we have a proportional valve the operator has the spool only approximately half open not even and is wanting to control the rate at which the cylinder extents that sounds like a perfectly normal thing to do decide how fast I want the cylinder to extend well if the valve is only half open and we have a lot more flow available from that gear pump the remaining flow has to pass over the relief valve because pushing against a valve spool that's only partway open builds up the pressure between the gear pump and the spool at maximum system pressure cracks our relief valve and so if we go over to our energy graph on the left here on the vertical axis we see flow rate we see our pump is pumping at maximum flow rate and because our relief valve is open we're all so pumping at at maximum pressure but the yellow box is of interest because that's our flow and pressure at the cylinder where our desired work is happening and so we'll see that we're only at about half of the available flow because the operator wants the cylinder to be slow and we'll only see that we're only using a small fraction of the system's total pressure yes the cylinder is very lightly loaded at this moment so what about that diagonal line well that diagonal line as many of you know that's our horsepower line our power line letting us know how much power does it take to move the load well this green diagonal gives us an indication of how much power that is it's a function of both the amount of flow and pressure where our gear pump the source of the system with the relief valve the the length of that diagonal line for both a pressure and flow is much longer so what one can see is that the length of the dark blue line so much longer than the length of the green line that's comparing the the power required for the load versus the power required for the whole system and hence the reason we fill in that blue area with lots of red that is wasted energy input whereas if we were running with a compensated pump let's change look at what happens with a compensated pump yes with the valve the proportional valve only partially opened that is still going to trigger the pressure compensator which will now put us in true variable displacement mode where at an operating point in the active region this graph should look familiar to you if you look through the data sheets for piston pumps you will commonly see this graph with a start of a downhill slope letting you know how much internal leakage may happen in that pump as you come up to the corner and at the corner here where we trigger into the pressure compensator function it falls off much more steeply and on this steep slope called the active region we are now with the swash plate somewhere between minimum and maximum moving back and forth constantly triggering as pressure drops a little bit due to internal leakage the pump comes back on stroke as the pressure compensator closes using the bias spring until those Pistons find out that yes the directional valve the proportional valve is still only partly open and we quickly build up the pressure so we are here at a constant pressure value but at least now our pump is supplying only the flow required at the working end of the hydraulics meaning the directional valve in cylinder and so our blue line our dark blue line is not quite as long as it was when it went corner to corner we have certainly saved a certain amount of energy perhaps we could beat that yet but that's a topic for late August when we get into load sensing all right so to answer our pop quiz question of the day which I think was hey why use one of these swashplate pumps I think that you can see and I see that some of you have certainly answered it there you you've got it right this type of pump will save you some energy for certain energy at both the electric level if it's an industrial plant diesel fuel if you're working with a an engine powered prime mover perhaps and if you save that energy then you also kept your hydraulic system a bit cooler all right that's great let's go over to questions that you may have today and see what's happening Andrew asks is case drain flow large enough that it could be a useful place to put the oil oil cooler yeah you know k stream flow is usually not something that you want to interrupt some pump manufacturers will say hey that case drain pressure going back to tank don't let that pressure right at the pumps case drain outlet port get any higher than then perhaps one bar 15 psi other pump manufacturers will have a different scenario where they might allow it to come all the way up to perhaps 75 80 psi perhaps five bar but usually no usually that even for a class II you asked about a closed loop system yeah but case drain flow usually has to be left uninterrupted on its way back to tank if additional cooling is needed then typically another kidney loop pumping unit is involved drawing fluid out of the tank and through a cooler for that great question though some people do put a filter on their case drain line back to tank and again that's that's a contentious matter because it can easily bring up your case drain pressure to a high enough level that you are interfering a little bit with the pumps pressure compensator action and also the natural migration of lubrication flows through all the working pieces inside that pump jellal asks he's asking about the best adjustable how much the do how much should be the difference between the compensator and the relief valve yeah jellal it tends to vary from system to system some pump manufacturers let's see you what are all the factors there so the the steepness of that of that line in the active region is a factor as is the override value for a relief out so typically you want to have a little bit of separation there so that the relief valve and the pumps pressure compensator never have a moment where they might overlap and both try to react to a high-pressure condition so it tends to run the range of having the relief valve set 150 psi higher to sometimes having that relief I'll set up to 400 psi higher so check with the manufacturer of your machinery your hydraulic system or check with the manufacturer of the pumps that you're going to use and see what they recommend there there is a bit of a variance out there on that topic Arnab asks about the pump not needing an unloaded valve let me think about that an unload valve so an unload valve yes typically a non load valve if I understand Arnab is there to take all pressure out of the system bring you down to very low standby there's a number of ways to achieve that even with piston pumps can be very advantageous if there is a long period of standby over top of just letting even a pressure compensated pump BD stroked but at high pressure so those are very those are very advantageous and especially for long times when when there is no call for pump flow in the hydraulic system I hope I answer that it's not necessarily critical if if the manufacturer has determined that the pump will cycle on and off and use flow on a continuous basis different designs let's see here tool time Chris do you think it's acceptable to use a motor with no load as a flow meter Oh to measure shaft rpm well that's clever Chris I think there are some flow measurement devices out there that have rotary shaft devices in them I haven't thought of using a actual hydraulic motor I think maybe you want to work with a hydraulic motor that has the minimum amount of internal static friction a very a very high mechanical efficiency rating I guess where is that the right way to think of it Harmon any way you want to be you want to where the hydraulic motor that that spins very easily perhaps so that the flow meter itself doesn't load the hydraulic system I can't see why that why that wouldn't work very clever let's see here savers asking do you think for the Rexroth a 10 V that you have to have pressure cut off there and perhaps there's no need for a system relief valve yeah there are certainly hydraulic systems we bump into where if the user is very confident that there will be no pressure spikes and the user and by that I do mean the hydraulic system engineering group they're the ones ultimately responsible for the safe design of system but if they're convinced there will be no pressure spikes then I do run into occasionally systems that have no relief valve together with the with the use of an 8 NV pump so yes that does happen can I be very careful with that and understand what maintenance and adjustments are required ok but most cases that relief valve is there to protect from from fast pressure spikes that can occur in the system and is the faster-acting device compared to the pressure compensator okay so I am why no means ever encouraging anyone to remove the relief valve from a system of the pressure compensated pump as an experiment always go back to an engineering group for your system before changing anything alright we'll move on there's a few more questions there that came in late but I think for now we'll move on or perhaps I'll come back to those a little bit later so just in case we need to look at a little bit more Hardware here we've been working in abstraction with simulations and what-have-you just to remind you of the pieces or perhaps if you haven't had a lot of exposure to disassembled piston pumps on the inside which is always possible I think you're gonna recognize some of the pieces here that you saw in our 3d movies things that you saw in our this is a pump obviously that's been decommissioned it's fairly simple and basic straightforward design where the control pill there's that little maximum stroke limiting or if this is fairly large right so also you get two off stroke and your case train flow because this is draining into the case and also in the flow rate coming off the case train line is very high you've uncovered that port you've gone as far as you can your pump is at the zero Degree stroke angle okay by the way it's easy to figure out from these three point here's where the pressure compensator was sitting a few moments ago before I took it off and if you cover that one with your finger no it's this one in the middle here all of a sudden you could see that that's clearly the one I'm pumping a little air against my finger there so that's the passage that is directing fluid into the control piston to D stroke the pump and where does it come from this passage back here which is monitoring the pumps outlet port and through a little pressure compensates pool that sits there inside the compensator here's our compensator make sure that if you ever take a compensator apart that that spool goes back in the right way sometimes the bleed orifice in the middle of the spool is meant to be pointed out towards the adjustment sometimes the other way around it depends on what internal passages have been set up in there to bleed down the backside of the compensator so there's the spring there's the cup washer that the bull-nosed end of our of our spool rides against there's our adjustment okay and remove that from there earlier and then of course that controller exhaust on the compensator spool dropping down through the hole closest to the connection between the cap and the case draining inside the case through that passage right there I was to stick my screwdriver right down in there you'd see it in that little hole right there where a squirt fluid through it with one of our syringes so that's some basic activity and if I was adjusting the maximum volume stop I think you can see that the control piston is extending so we'll no longer get the 20 degree angle perhaps we're only going to get the 10 degree angle unless we turn it back out and allow the pump to be larger so this literally limits the maximum size the maximum pumping displacement volume of the of the piston pump right and so what are we supposed to picture the cylinder barrel of course turning there and right how do we prevent a lot of leakage from happening between there well what you'll notice is that under the ball washer underneath the spherical washer if we look in there there's three tiny little pins holding the retaining ring at a distance and if I was to squeeze this you'd see oh yeah there's definitely some spring action in there there's a there's a load spring there's a load spring inside the cylinder barrel and as you put the pump back together assuming here a pump rebuild person when you tighten up those cap screws to fasten the cap end of the pump to the body you find the last few threads there's some resistance there you're tensioning the the slipper pads the piston shoes against the swashplate that you can see inside the pump casing you see it in there at an angle looking in through the case drain I could see the bias spring in there so there's all of the basic pieces that we've been talking about and hope that clarify some of those now we'll come back to transverse design here in a minute maybe just before we move away let's go in adjust a few pumps and and that are of this style with a control piston axially in an axial orientation meaning in line with the pump shaft and you what that's all about okay so we've got a a Rexroth pump over here just going to make sure that my flow is all the way open here I'm pretty sure it is okay and we can see that we're we're pumping at 1.2 gallons per minute this one does not have a maximum volume stop so this one's only going to have pressure compensate so with lots of flow taking place there right now I think what you'll notice is that is that you know we're not in the right state to adjust the pressure compensator the pumps outlet line is simply pumping back to tank and and and right back through the filter and so it's pretty easy easy flow path not a good state for adjusting the pumps pressure compensator doll we're measuring the pressure on the pump outlet line here it is we're measuring the pumps pressure on the outlet line with the digital gauge and oh yes you might notice that we've got the load sense compensator on there this is a DFR compensator if you're reading the datasheet for the style of pump but in this particular case with the control hose coming out of the DFR style compensator the valves set to route that compensator right into the pumps outlet pressure that basically knocks out the compensator the load sense compensator as it's sometimes called at this time so right now the way we've got it configured at this very moment we really only have the single pressure compensator adjustment okay and as I take my trusty three-and-a-half millimeter or my three millimeter key off to work on this particular adjustment of course we're not in the right state when we have a free and easy flow path so if I was to make any changes to the pressure compensate now we'll find out nothing's happening on my pressure gauge so I've got two blind out the flow of the pump and I'll do that by shutting in okay very gradually shut in the pump our flow rate drops off to zero and we can see now that currently our pressure compensate value is around 500 psi then perhaps it's supposed to be closer to 750 I've already got my jam nut backed off in advance and so as they make the turn gradually that's about a corridor turn there and if I'm supposed to come up to 750 I need to go a little farther and it's not quite that wasn't quite half a turn I overshot take my time I'll come back down go underneath a little bit and just give it very small wasn't even about a third of a turn to go from 500 to 750 on the pressure compensate and it's it's all about complicated our pressure compensator has been set and again the assumption is if you have a relief valve in a system that that has already been adjusted okay so that's one example let's head over to another unit where I have to get in a little closer and of course there can be heat involved so I'll put on some gloves just to be careful hydraulic systems can be very hot after a time I warm these systems up a little bit today but they've already cooled down a little bit and we start with our our flow rate let's have a look yes we're open to having around three quarters of a gallon 0.75 very small flow rates these are the pump units that typically accompany our our training valve boards and they're just sitting side-by-side together and we've created some basic flow loops from pump outlet through a needle valve and then simply back to tank so a very simple flow loop with some sort of a needle valve so that we can shut in the flow and make adjustments as needed so right now we don't know what our what are our maximum system pressure would be because we've got a nice easy flow path and our our system pressure is certainly quite low well under 100 psi so let's find out see where we are by very slowly closing off the flow rate will drop and the pressure will come up as our flow rate drops off to zero we find out that our pressure compensate at the moment is around 600 perhaps our pressure compensator is supposed to be closer to 750 so just got to grab the right key and dialing into our pressure always check your manuals to find out where your pressure compensator is located make very careful adjustments in this case to go from 600 to 750 was only about an eighth of a turn it's a very small amount of turn on this key to move 150 psi about a quarter of a turn was 300 psi change on this particular adjustment this is a nachi america pump you'll see the datasheet for so there we are back at 600 what am i saying oh yeah we wanted to go to 750 perhaps that's our correct setting and there it is and of course then we would apply the correct torque to the jam nut and lock it so that it doesn't move after we're correctly set in this case we can also adjust the maximum volume Oh perhaps before we do that let's have a look at the key strain flow meter okay should case drain flow meters be left in place I don't recommend it we find that that places additional resistance on the key strain line and if you don't know what values you're looking for perhaps not all that useful to leave it there but in some cases what it does tell us is that there is an increase in pressure as you'll see the key strain line flow meter is increasing we're nowhere near 750 our pressure compensate pressure we're only at about 450 pump outlet pressure now 500 pump outlet pressure 550 600 psi and we're up to 0.15 gPMs of flow on the key strain and if I shut it in completely if I shut in the pumps outlet you'll see that there is the highest level of flow on that case train line that you'll ever see due to the pressure due to the clearance between parts and also due to controller exhaust and the maximum stroke of the control piston okay but if we want to change the maximum flow we were at point seven or something when we were wide open this is obviously not the time to change maximum flow rate but they the maximum volume stop on the pump because we're currently in the zero flow condition we need to open the system back up for free and easy flow perhaps point seven eight gallons per minute is not correct perhaps what we were supposed to be set to is one gallon a minute so which way do I have to turn the adjustment screw well with one of these axial in line control Pistons which are very a typical design typically to make the pump larger one needs to turn counterclockwise this is an adjustment that's lower down on the cap end of the pump and I'm just going to turn counterclockwise and find out that our pump flow rate as being measured through web tech turbine flow meter is increasing on the display 0.91 and i should also mention that there may be a recommended correct temperature for your system to make these changes I believe I mentioned temperature a moment ago and I didn't finish that because not so much flow perhaps a little bit flow I will change but most certainly the pressure compensating value now pressure compensated and maximum flow rate may change a bit as you come to the nominal normal working temperatures and then of course you must be careful not to get burned by hot hydraulic parts okay so there we are we have adjusted both the pressure compensate and the flow rate our flow rate is now at about one gallon a minute if I shut the flow rate back in our pressure compensate value should not have changed that should be about 750 those two settings are largely separate from each other independent as long as you did them at a similar time when the oil was at a nominal level required for making the correct adjustments alright that's a couple of adjustments for pressure cutoff for compensate and also for maximum volume stop let's think about another style of pump it's not uncommon perhaps just a little less common but not uncommon to find pumps that have control the control equipment the control piston set across the case in in a transverse arrangement as opposed to control Pistons that were in line with the axis oil gears certainly been popular with that over the years a few other pump manufacturers as well have had various pump controllers where the action for angling the swash plate the control piston the pressure compensate functions sit at an angle across the case and that's just another design to go possibilities of getting certain kinds of strength and what-have-you and of course I didn't mention earlier this you know these pumps can be rated for very different pressures so this one with a very thick casing and in a number of special places with bearing surfaces on the inside this one has continuous run at 5,000 psi intermittent up to 5800 where perhaps the rx Roth 810 the one we've got anyway about a 3600 psi nominal pressure perhaps a bit over 4,000 for for intermittent whereas the one I was just adjusting a moment to go the design intention for that one is for it to max out nominal run at around 3000 psi and and maybe intermittent about 3500 so they're all similar size but have different top-end pressures and perhaps some are more heavy-duty than than others okay this particular pump though with all of the transverse could we bonnet configured with about as many controls as you can ever sort of get all combined all at the same time so the pressure compensated justment is sitting here this is the adjustment for the maximum cutoff pressure that's the one we've been talking about the most and then the maximum volume stop meaning how large can we allow this pump to be or do we need to shrink it down from its maximum that's this adjustment screw over here and perhaps this one's not quite as common you might be saying hey what's that one sticking out well we deliberately ordered it with this this is a minimum vol stop RQ minimum what happens if you start to turn that one clockwise with Q minimum you're literally in a scenario where if you dial it away from its factory setting dial it clockwise you're going to set up this pump in such a way that the swashplate when you go into pressure compensate function the swashplate will not quite make it to the zero degree angle meaning it's going to remain on stroke even once pressure compensate hits usually very small amount if any of that is dialed in it's not an everyday common value to be dialed in but we do encounter it on steering pumps on some mobile equipment where it is desirable to still have some flow definitely coming out of that pump even when fully compensated which then does definitely require a a relief valve a system relief valve to be present in parallel for for protection in parallel with the system okay so that's what that is so that's a minimum volume stop Q minimum and then of course some of you may may well know what this adjustment is over here load sensing we don't have a line connected to it on this one it's just fresh out of the box that's where load sensing is and again come come and join us in in August for our U for our live broadcast at that time on on load sensing all right so a transverse-mounted controller I've got a few little three-dimensional clips to show you on that topic so let's find those okay so just to give you a bit of a picture there we're gonna start to shut in the flow rate coming out of the outlet for an oil gear pump here we're gonna shut it in block off the flow you could see that our pressure spiked up so our flow meter showed two drop-off in flow and our system pressure spiked all the way up and watch here there is a passage from the outlet of the pump that's actually carved right or drilled right through a very thick pump casing and brought up to the underside of that pump controller in our three dimensions we lifted the pump controller up from the surface of the pump so we could see the linkage a little bit so a little bit unrealistic there this gap does not exist but it's easier for training and that flow from the pumps outlet comes to a small passage that's sitting just about here underneath the compensator spool so there's an adjustment I was just showing you a moment ago that lets you tension the spring for compensator function outlet flow or outlet oil pressure also travels past a smaller diameter land on the compensator spool and comes down to the end to act on the end of that spool as well to push it against spring setting that perhaps you dialed in for what you desired for your maximum system pressure okay so here it is so right now just I'm gonna I'm gonna stop and pause a lot to just catch the moments so our swash plate angle might be maximum there's our zero Degree reference and as that as that spool opens that pressure compensate sorry the system outlet pressure made available runs across to our control piston and linkage in this slot is connected to a rod down below to move our swash plate to the zero off stroke condition as you just saw it there so a lighter spring here but a control piston that moves and hits against the minimum volume stop which is dialed out to zero hopefully unless you need some there's our maximum we'll get to that one in the next movie here in the next clip so just looking at it from the side we can see if the pump is off stroke although you really need to see down from the top and so that's why we showed it with those green lines we're in the pressure compensate mode okay one last three-dimensional clip here for us to have a look at and this one involves this is what happens here if we're going to adjust the maximum volume of the pump in other words make that pump just a little smaller than its maximum possible flow rate and so what's involved well this is where we bring in an allen key a hex key you saw it shoot in there in the upper right hand corner of the screen and of course as you know this is done when there an open flow path for the pumps outlet flow pump oil is flowing very freely back to tank with with little to no obstruction or pressure loading and then is we turn that allen key we find out that we're just literally changing you saw the angle of the swash plate there change I'll just back that up again if you didn't catch it if you want to look below to see what happens with the swash plate we're literally limiting the maximum size perhaps we've cut the size of the pump in half because maximum flow was perhaps too great for whatever reason alright so let's head over to the oil gear pump here with the transverse control and let's make one more set of adjustments so you could see that taking place will fire up our pump obviously we've got a free and easy flow path right now for oil leaving the pumps outlet traveling back to tank unrestricted because we do have the pressure because we do also have the load sense control on there I have a hose on the pump outlet connected right back into the pump control and it arrives here and basically using the system pressure to knock out the reaction of of load sensing come back in August and we'll run this pump with load sensing functions and in a variety of different loads on a hydraulic system at that time so perhaps since we've got a nice open flow path I'll reverse the order of my action this time we've got a nice easy open flow path perhaps point eight gallons per minute is not the correct maximum amount of flow perhaps our pump is supposed to be a little bit larger perhaps closer to one gallon per minute so which way should I go should I go clockwise or counterclockwise well as you'll find out what we need to do to get that pump to be larger is go counterclockwise on the adjustment screw and here comes our flow okay so we're increasing the maximum flow rate from point E gallons a minute up to one gallon per minute and it was simply a matter of counter clockwise turns on the maximum volume stop okay let's think about what happens here is we need to work on our your comp saying let's watch that case drain flow meter as well the case drain flow meter well will notice as we shut in the pumps flow a little ways to go a little bit oversized needle valve there it comes I'm starting to restrict the flow coming out of the pump and of course you'll notice the case drain flow on the increase down to about 3/4 of a gallon a minute up to about 600 psi and our pump is off stroke and we revealed our current pressure compensate value is 600 psi and so now if it perhaps supposed to be 750 psi with the jam nuts backed off and loosened to take my hex key to that pressure compensate control on the opposite side of the pump and turn clockwise to increase the system Maximus system pressure adjusted when flow has been blinded out up to 750 psi and that was less than a quarter of a turn to make that 150 psi change and again adjustment should be made at a nominal system operating temperature but it's not too much more complicated than what you've seen I'll go back and restore my flow which takes out system pressure but we're in our flow comes back our case stream flow of course drops right off and that's the adjustment of a pump with the transverse control the oil gear in this case alright let's go back and see what questions remain from from the viewing group today thanks for being with us yeah black cones is what's the main application for piston pumps well piston pumps are fairly good heavy-duty pump perhaps gear pumps can can take more abuse so if it's all about abuse perhaps and not about energy savings perhaps one would choose a gear pump which is common for hoists on haul trucks and all kinds of very heavy-duty applications let the piston pump gives you the ability to control it gives the ability to work with a multiple of number of different pressures depending on what type of controller you've got there can be torque or horsepower limiting controllers which can help prevent the engine from stalling if the system is overloaded there's just so many control options that come with piston pumps and of course as we mentioned back near the beginning energy savings for sure by not pumping over a relief valve any more than absolutely necessary Thanks great question Andrews asking is that Q minimum used to prevent the slight delay in pump stroking up from zero yeah that's an interesting thought Andrew sounds like you've come across a few machines that that we have there there are machines out there where that Q max is moved away from the zero degree angle to produce a certain servo or control pressure throughout a hydraulic system where a number of other control valves will need to react when the system is kind of in a low almost a neutral State and so yeah sometimes that Q minimum that you asked about is moved off of zero just a little bit can make it easy to produce a higher piloting or standby pressure yeah good one Andrew also has a comment there yeah okay great oh yes very good point I did not point out that the electric motor current is at its lowest while the pump is at maximum flow and at zero pressure yes but what you would also find out Andrew is that when we when we get to the flow cutoff point closing in the needle valve the current goes to a very high point and then just as you close in that needle valve that all sudden the amperage drops off again because you can maintain high pressure but if you reduce the flow volume that does not take as much power from the prime mover as it does when we're at both full volume and full pressure nothing requires more horsepower from your prime mover very good point for you to bring that up nothing requires more power from your prime mover than pumping at high and full flow if you get rid of one or the other you could pump at high flow and low pressure and save a lot of horsepower or you can pump at high pressure low flow and save a lot of horsepower but anytime you have your pump at maximum flow rate and at maximum pressure you're drawing that's that diagonal line across the square box in that pump efficiency chart we are looking at that lot that long diagonal line requiring the most amount of power great observation Andrew thank you trigger Tex has any advantage to a hybrid hybrid system that's using variable frequency drive motor and pressure comp um yeah well variable frequency drive electric prime mover is being hooked up to fixed displacement pumps is certainly a very common thing now with electronic controls being what they are a lot of opportunities are presented to save energy and so that is becoming a very common package I'm sure before long and our own training fleet will have a fixed displacement pump driven by a variable frequency drive motor but I think you're asking about a variable frequency drive motor together with a variable displacement pump a pressure compensated pump not it's common that doesn't mean we haven't seen it we came across one stationary installation a good number of years ago where variable frequency drive motor and load sense piston pumps were used together and yeah that became quite a tricky system to create the right control schemes for it is doable though lots of energy savings available it is doable for some hydraulic system designs depends on the application and the usage samer asks how can i let's seize identified by the valve plate whether the pump is a right or a left hand shaft right well that's a good question savers so look all over on the pump case quite often there will be a directional arrow indicating what direction the shaft is supposed to turn sometimes that arrow is it's just sticking out of the casting in a very nondescript way and it's got the same color paint as everything else and can be a little hard see in fact I think instructor mark here actually took a black sharpie and darkened in the flow arrow on ours that was just sticking out of the casting had the same color of you know sky-blue paint on it might not have noticed it on another pump let's look over here and let's look on this one here we see the the directional rotation arrow is on the nameplate so don't let the nameplate get lost or get damaged so it's there but Samer it can also and almost always does show up in the many letters and numbers of the model code so take that model code off the nameplate get the datasheet and examine and that way is one of your best ways to verify if if if the Inlet and outlet port are different size as they often are on piston pumps not always that can help you but you also have to know then what the swash plate is doing on the inside so not necessarily as easy to figure it out that way good question Keir john alba said one about a vane type of pump what about them right aren't they great yeah they could be very high efficiency compact a lot of them are made now to be so quiet there is a lot of advantages to vane pumps and perhaps will cover those at a future date and you're right there can be vane pumps that our pressure compensated and what-have-you and controlled but not as common as as the piston pumps so perhaps well well cover off on vane pumps on on a future session okay can I understand let's see I'm not sure if I'll have too much more time for other questions today maybe one last one here by measuring the case drain can we comment can we understand the pump condition by case train flow very tricky subject and not always easy to do yeah that's that's just really not an easy one if you can detect the the condition of a a pump by its case drain flow and quite often you're at five seconds to midnight and many many other golden opportunities to measure the problem with a the piston pump through volumetric efficiency testing have gone by but there have been times when observing case drain flow and finding out that it was unusual compared to an identical pump sitting right next to it and that has been a clue for us to to to dig in on a on a problem with a pump where the fastest thing we could do in a service condition in a coffee break between between work cycles was to take the smaller hose off the case drain line and measure and find out that that an overheating a badly overheating pump had an extremely high value on the case drain much higher than the pump datasheet said it should ever be and so yes it can be a clue but not always easy what I like to see the case drain flow meter telling me is that the pump has gone off stroke when it's at a certain level you know some other things like that but leaving it there permanently does tend to cause some can cause some problems as well unless you know how much resistance that case drain flow meter issues are offers against the the resistance of case train flow which should be kept very minimal okay all right I think we're coming down to our to the end here today and if you had additional questions and we didn't get to them feel free to email them to us and we'll be glad to continue to take those up with you info at lunch box sessions comm or find me on linkedin carl dyke industrial teacher and send me your questions that way thanks for joining us today lunchbox sessions and CD industrial group is myself carl owen mark nathan crystal robin chris ivan alex and Lenore and also a special mention to ted kealan Emily and grant for all of their contributions throughout the last year thanks also to our good friends at fluid power WorldCom and our sponsor today thank you oil gear and our next our next live broadcast will be on June the 9th we'll have a very different type of scenario set up here to look like a bit of a mad science lab test tubes and and what-have-you and electronic laser particle counting equipment so come on back on June 9th to talk about particle contaminants and we'd love to have you then keep up with our skill julen topics at lunch box sessions dot-com / live thanks to you the participants for joining us today it was great interacting with you see you soon this is Carl from lunchbox sessions calm bye-bye

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