Looking for Boom Lift or man lift salvage yards. I am specifically looking for a drive brake valve block assembly for my 1980 marklift 60 foot boom lift. I cannot find the new part which is part number Terex 21082. Also attached is a picture of the ID stamp on the block assembly which shows it as Fluid Controls Inc out of Mentor Ohio with some numbers stamped on it. But that hydraulic controls company was apparently sold or out of business.
Help please anyone?
Whats the problem
It's a long shot, but try Farmland Tractor in Tangent, Oregon
Not enough hydraulic pressure and volume going to the hydraulic wheel drive Motors. Only 1200 lb. I have 2500 lb hydraulic pressure, which is the maximum for the pump, going into the drive brake valve block for both forward and reverse lines, but only 1200 lb coming out of the forward and reverse lines going to the hydraulic wheel Motors. So I suspect an internal leak or malfunction in the drive brake valve block. When I cap off all four of the exit lines from the valve block and blow into one of the inlet ports with my mouth, air comes back out the other Inlet line port. So I suspect that there is a leak between the two Inlet ports inside the block?
Here is a different part number from the PDF manual hydraulic schematic page for this drive brake valve block 21214.
Could it be the relief valve on one of your travel motors is dumping to tank too soon
What if you were to cap the ports for the hoses going to each of the travel motors what would your pressure be then
Thanks fun I will have to do some more testing that way. Where does the hydraulic fluid go after the travel motors forward function is engaged? Does it all go back to the main hydraulic tank reservoir through the small relief hose from the travel motor, or does most of it go back through the reverse hose?
Should return through opposite hose back through control valve and then to tank. Typically, you'll see 3 maybe 4 hoses to each motor. 2 beefy ones will be your A/B travel . Next size down would be case drain and the dinky one if it has it, should be for 2 speed change over. I would want to see the oil pressure going to each motor one by one capping off all others. This way you are removing consumers as a source of loss. Good luck. CAUTION!!!! Do not cap all ports, it may leave you with a "No Relief" condition.
I assume the A/B travel means the beefy forward and reverse hose lines? Not sure what you mean with the word "consumers", internal leaks with other components, such as a drive motor or valve Bank? I previously capped off the beefy reverse hose before the connection to the drive brake valve bank, and attached the pressure gauge to the inlet beefy hose before the valve bank and it held at 2500 lb and did not blow any lines out. So I'm assuming that there must have been some kind of relief valve between the proportional valve manifold and the drive brake manifold?
I use consumer to describe "the thing that does work " whether a cylinder, motor whatever. Sorry for the confusion I describe electrical systems in the same manner. Consumers use energy to do work.
This is a third or fourth thread you started about the same machine! It’s been almost half a year, I don’t remember all the details when the previous is ended. Did you know for sure you have a crack in that block or you only think you have a crack?
As far as I remember that machine does not have a relief valve in the motors, counterbalance valves are in that block and high speed shifts by mechanical linkage from cylinder which takes its supply from the same block and shares it with steering circuit.
Thanks fun. Now I understand what you mean by consumers.
Yes TVA, I have had several issues with this machine, and this post got into another issue when senior member Mikebramel asked me what the problem was, why was I looking for a used drive brake valve block. No, I don't know if there is a crack inside the block, that was just suggested to me as a possibility by a service manager a lift boom rental company. So I took the valve block to a hydraulic shop yesterday and the service man there thinks that the spring ball and seat in the block in the attached picture may be causing a leak inside the block between A&B Inlet large beefy lines, even though he could see no scratches or other defects with the naked eye. The service man said that with all of the exit block lines capped off, when you blow into the one Inlet beefy line coming into the valve block, that there should not be air coming back out the other beefy line port.
That looks like check valve, I highly doubtful that it is not doing it’s job if there’s no damage to seat or a ball, unless spring installed wrong or ball of wrong size. You should have two of them there! If one leaks and the other doesn’t - take both out and compare to each other, I think the seats for them is inside the block and not in the cap!
Yes the seat is inside the valve not the cap. I will compare the two balls with a micrometer.
TVA, I got an email notification of a post you made at 7:15 a.m. this morning, but post does not appear in this thread? Following is the text that appeared in the email: If that is counterbalance valve - there’s should be a pilot line passage between two ports! That’s how return to tank side gets opened up when you have pressure on on pressure side! On the other hand counterbalance valve can leak out your pressure to drain port if it’s damaged. And drain is not the same as return, although it connected to it.
So if I understand correctly, each counterbalance Dynamic brake valve uses the travel wheel hydraulic motors as a braking mechanism, kind of like an engine brake in a truck? And the heavy duty springs adjustment determines the stopping distance from 1 to several feet? And after it stops then the parking brake kicks in? And it looks like the mechanical brake drum in the wheel hub is really a parking brake since there is just one small hydraulic line going to one small adjustment needle on the drive brake valve cylinder block?
Something like that, the only thing that on manlifts ( at least on newer ones ) everything is on counterbalance valves - safety thing! Dealing with humans!
Thank you everyone. Looks like I've got some more testing to do. I'm going to cap off all of the beefy exit lines from the valve block and check the exit pressure on each one individually. And if I am still getting the reduced pressure at 1200 lb instead of the inlet pressure of 2500 lb, then I am thinking I will just start removing the internal components from the inside of the drive brake valve block and see if that affects the exit pressure on each exit port?
What way of thinking made you come up with that idea?! OK, let’s start with publishing that diagram AGAIN, because I’m not gonna be looking for it in archives! Stop jumping all over the place, randomly checking stuff , and come up with method and the plan! 2500 psi, is it what you see on your main control valve test port, or you see at your drive block inlet?
Thanks for your patience TVA! 2500 psi is what I get on the Drive block Inlet both forward and reverse lines and also what I get at the proportional valve manifold, and 2500 PSI is also the maximum PSI rating on the identification plate for the machine. 1200 PSI is what I get on one of the large beefy Outlet lines from the drive brake block. I have not yet tested the other three block outlet ports. I am attaching the hydraulic schematic entire page and the zoomed up drive brake block section, and a hose diagram page.
What happens if you plug the shift/break port? Still loosing pressure?
I can also upload pictures of the Dynamic brake counterbalance valves and the flow divider valve within the drive brake block if you would like to see those.
Yes I was still losing pressure when I did that test previously. And I also blocked off the inlet and Outlet lines to the little two Speed Shift cylinder as well, which was something that you had suggested I try previously.
Funny like they show on diagram that shift cylinder and break release on the same branch outside the block, but in reality it is different ports in the block.
I know what you mean. These PDF service manuals leave a lot to be desired. PDF Pages out of order, and different part numbers showing on that valve block for example on the hydraulic schematic than what it shows on the parts page. And this marklift Model 62 PDF manual had absolutely no description about the dynamic break counterbalance valve adjustments, but I found the description in a PDF manual for a marklift scissor lift. And I was also recently advised that marklift used the same exact drive brake block part number 21214 on all of it's boom lift and scissor lift models, thousands of which were produced. Which surprises me that I cannot find even a used one.
Did you measure the pressure on both inlets of drive block, or only on one? Your MCV show pressure reducer but only on one side. Can it be what reduced your pressure but you have gauge on different side on inlet and outlet?
Actually - scratch that! I was wrong!
Does it have low pressure both directions? Forward and backwards?
I measured high pressure at 2500 PSI for both of the inlet lines to the drive brake block, but I have only tested one of the four beefy outlet lines. That's on my to-do list.
Let me clarify: you had 2500 on one inlet going one way and 0 going the other way, and totally opposite on the other inlet? Or it’s 2500psi regardless?
Another very important question: does your inlet pressure drops when you trying to drive or it’s stays the same?! Trying to find out weather block is bypassing or restricting.
I have one pressure gauge. I wanted to eliminate the turret rotation manifold as a possible leak source , so I connected the Gage to one of the two beefy lines that goes into the drive brake manifold. I did not t the gauge into the line, but instead just made the gauge a dead-end connection for that hose, and the other incoming hose to the drive brake manifold I just capped it off. When I engaged Drive function, I left it fully engaged for about 5 Seconds and the pressure held at 2500 lb, which tells me that there were no leaks between the proportional valve manifold and the drive brake valve block. Then I did the same test with the other incoming line to the drive brake valve block and it also held pressure at 2500 lb. If I remember correctly, I capped off three of the four out going beefy hoses from the drive brake manifold to the hydraulic motors and also capped off the parking brake line from the drive brake manifold and another line from the drive brake manifold to the two speed shift cylinder, and put the gauge on the one remaining beefy hose from the drive brake manifold as an end connection. Both of the inlet hoses from the proportional valve Bank to the drive brake manifold were connected. When I engauged the drive function, the pressure gauge only went up to 1200 lb and held it at that until I disengaged the drive function. So either the drive brake valve block was leaking fluid back through the other incoming hose, or it was just blocking off the higher pressure? One more notation that may be of help, when I have the valve block off of the machine and all four exit ports capped off, if I blow into one of the large two Inlet ports, a lot of air comes out of the other inlet port.
Shuttle valve for shift cylinder and park break release would be the first suspect for cross port leakage. On the picture red arrow either shuttle valve or check valve for counterbalance marked with yellow arrow.
Yes TVA, the local hydraulic shop I took the block to said the same thing and I watched the technician remove both of the shuttle valves and look at the little spring and steel balls and the seat inside the block ( picture posted earlier in this thread) and he could see no visible damage, and he also took some measurements with a micrometer inside the shuttle area of the block, and said he could see no damage, but would recommend replacement of those shuttles, and he looked for some part numbers on the shuttle cap head and sides, but could find no numbers. So I am curious, if I remove the shuttle cap and springs, and physically hold the balls on their seat with my fingers or a stiffer spring or something, should that keep the air from passing between the two large beefy Inlet ports to the hydraulic brake block? Maybe I could spend the balls around and see if that provides a better seal? Or install stiffer Springs to hold the balls more tightly to the seat?
okay I'm just now editing this. So I'm guessing the ball and spring in the picture is the check valve, not the shuttle valve? And also FYI there are two sets of these balls Springs and caps, one on top of the block and one on the bottom of the block, and each one connects to a separate Dynamic brake block counterbalance valve with the big heavy duty spring that you have the yellow arrow drawn to.
There’s a difference in shuttle valve and check valve. You show two checks and one shuttle! Although sometimes one shuttle can be comprised by two checks. Your shuttle valve should look like longer two step cartridge valve, and should have no springs in it, if it’s ball or spool a I can’t tell you. But it should have passage to both inlets and shift cylinder and park break hoses.
That is check valve not shuttle!
The red arrows is check valves, the green arrow is shuttle!
Okay I just edited the text on my last post with the picture. Sorry
The shuttles and checks operate on pressure difference between two ports, the spring inside checks is for assistance when pressure is low on start up. The ball type shuttles don’t have springs in them because springs will interfere with ball sealing on its seat, the spool type may or may not have weak springs in them!
Here’s example of shuttle valve cartridge https://wojanis.com/hydraulic-valves-cartridge/cartridge-valve-shuttle-valve.html
Here’s some more: https://ph.parker.com/us/en/cartridge-spool-type-shuttle-valve https://ph.parker.com/us/17567/en/cartridge-ball-type-shuttle-valve/csh101b
Thanks TVA. I'm going to disassemble the shuttle cartridge you have pictured with the yellow arrow, and I will get a picture of all of the components at both ends and Post-it a little later for you to see to hopefully help clarify my understanding.
By the yellow arrow I marked the counterbalance valve, not the shuttle valve, my post said: with red arrow I marked shuttle valve, OR!!! - check valve associated WITH!!! Counterbalance valve marked by yellow arrow! Because I don’t have pictures or illustrations, of all of the six sides of the block and it’s innards - I cant know for sure! But by the looks of it and proximity to components, I made two assumptions!
The red circle - counterbalance valve The blue arrow - adjustment screw you can see on on picture The yellow circle - the check valve associated with red circle counterbalance valve. Now you would have to look for shuttle valve, with connections I started in post above.
I don't see a picture with red and yellow circles?
Okay so I am going to post some pictures of the inside of the counterbalance valve as well as pictures of all six sides of the valve block, so give me about 10 or 15 minutes to do that since I can only post three pictures at a time. Also I made a big discovery yesterday when I took the valve block back apart. Apparently there is supposed to be cross port leakage between the two beefy in coming forward and reverse hydraulic lines to the valve block. I removed some of the allen screw plugs and saw that there was a hole drilled connecting those two Inlet ports. And the hole was about I would say 1/16 of an inch or 1/8 of an inch in diameter.
Parts in order from inside of dynamic brake counterbalance valve shaft. Not sure if I have the sleeve over the piston backwards or forwards, but I think it should be with the rubber o-ring towards the outside, the right side of the picture?
As far as I understand the top one is one of the counterbalance valves apart, the bottom three is flow divider apart.
Is this just a plug, or there’s small spool behind it?
Just a plug, with no spool behind it. With this plug removed I was able to see the small drilled hole connecting the two Inlet ports. And I shined a light and stuck a paperclip through the tiny small drilled hole to confirm it was unobstructed.
Show me under what plug those parts that in the three last pictures.
I thought this item pictured was the flow divider?
Yes you right! It’s been a while! Looks like two identical valves facing each other is your shuttle valve.
Did everything moved freely and no damage visible?
Yes everything moved freely with no visible damage. So if I am getting 2500 lb PSI coming into the valve block, should I still be getting 2500 lb going out to the drive Motors when I have the gauge on one outlet and the three others capped off? Considering that there is a drilled hole between the two Inlet ports inside the block, I would assume that fluid and pressure would be leaking back through one of those Inlet lines? And I would wonder where does that fluid go, back to the storage tank or back to the proportional valve manifold?
The drilled holes between inlets should go to shuttle valve cavity, to supply pressure for speed shift and parking break. Shuttle valves job is to open passage to high pressure side and close to low pressure ( return) side.
The return goes to tank, but it goes THROUGH proportional directional control valve. That valve ( MCV Main Control Valve ) is primarily Directional, I.e. changing direction of movement, the question of weather it is Full ON/OFF or proportional comes secondary. But we just like to call it MAIN Control Valve without specifying what type. They can also be open center or closed center, load sensing or non load sensing and have boat load of different actuation methods and combination of those and whole lot of different things.
So right now main question is: are we bypassing or restricting?! If inlet pressure will slowly drops a short while after actuation ( driving ) - then it is bypassing back to tank. If it’s staying pretty much close to same - then most likely it’s restring the flow.
Another thing that can bypass is counterbalance valve through those internal parts, pilot lines to tank. Got to pay attention to all the spoils and O-rings. Although internal crack is very much possible!
So when the return line goes through the proportional directional control valve, I assume that the return line is one of the big beefy lines either forward or reverse line?
Yes, you switch them around by moving MCV spool.
So I may have to reverse the sleeves over the Pistons in the counterbalance valves in the attached picture? I can't remember which direction they were when I took them out LOL I suspect the top one in each picture is the more correct configuration since if it was the other way, part of the O-ring would be in the path of the incoming fluid in the cavity.
Are those two was in the same cavity? If they were, it is shuttle valve ( why it is so big I have no idea), shuttle valve supposed to close the passage between low pressure inlet to speed shift/park break passage, leaving only high pressure side connected, and when you reverse direction - switch everything to another side. You noticed that barrels have different ends, I think one goes inside block to blind end, another to cap end. Put it’s for you to figure out which goes where.
No they are not in the same cavity, they are in separate cavities. Each one is in a cavity for each dynamic Drive brake counterbalance valve.
So I reconnected the drive brake valve block to the 2 in coming forward and reverse big beefy hoses and did a pressure check on each of the 4 exit beefy lines, and each one measured at 1200 lb instead of the 2400 lb at the incoming lines. ( I tried to upload an MP4 video but apparently the Forum does not accept that file extension) So now I am thinking I will reverse those two piston sleeves that I was unsure about the sleeve position and see if that kicks up the 1200 lb pressure to 2400 lb?
Does it bypasses or restricts?
Interesting that it drops pressure in half! Flow divider?!
I don't know if it bypasses or restricts. Since I have one of the outlets on the pressure gauge and capped off, and the other three Outlets capped off, I'm wondering if it's possible that part of the hydraulic flow is going back through one of the two Inlet beefy hoses that is not engaged? And if so, where would that fluid go if the proportional valve was already directing fluid to the other valve block Inlet line?
Damaged counterbalance valve, not fully seated shuttle valve will bypass to return side, how to check it - I already posted that. Still very interesting that it cuts pressure in half!
The schematic diagram would indicate a steel ball in the shuttle valve, but there was no steel ball in my shuttle valve, just a small 16th of an inch drilled hole connecting the two Inlet ports and the shift cylinder and parking brake circuits. I don't see where you gave instructions on checking the shuttle valve? That being said, I'm thinking of checking the pressure to the outlet big beefy lines after removing internal parts from the valve block one by one, and so I am thinking about starting with removing the flow divider valve completely and see what that does to the exit pressure?
So, because there’s no ball two inlet ports and speed shift/park break passages just open to each other full time?! I remember Grove menlift had that thing right underneath the 1/4 fitting, tiny little ball? You would have to shine your flashlight to see it! It was crimped over after it was dropped in there. So if you loos it you would have to re machine or replace the block! If that block not there - that is the problem!
Removing flow divider or counterbalance valves will open up cross port leakage even more!
you mean missing ball, not block, right?
Any way to get a manufacturers diagram and or part list on this block that is better then what I already posted from the marklift service manual?
Yes! Sorry! Fat fingers and was in a hurry! If the problem is missing ball: you can find one in places that sell fasteners, that’s if you have both seats for it! If not - if it’s possible drill and tap for plug , to block the passage between two inlet port, but in line shuttle valve and plumb it outside the block with tee fittings.
I’ve looked, not very hard though, didn’t find anything.
Could it be that ball inside the fitting, probably the one with needle valve? Anyway if it’s inside the fitting it’s got to be one with seals and it being cross point.
Not sure what you mean by Cross Point? And by needle valve do you mean that parking brake T fitting that screws into the top of the valve block pictured? And if so, I don't see how that could cause leakage, unless there was a leak inside the parking brake or brakes? But then again, I did have those lines to the parking brakes capped off when I took the pressure readings on the four block exit ports.
I understand what you're saying about drilling and plugging the passage between the two Inlet ports inside the block, but wondering if you could diagram the tees and where those lines would go?
Well, I discovered that there was an allen screw retainer in that shuttle valve, but instead of there being a ball on the other side, there was what looked like a bushing and tiny washer, see picture below. So when I plugged that channel, it stopped the leakage between the two Inlet ports and then I started getting the full 2500 lb of pressure in the outlet ports of the valve block. It seems like that little bushing with the hole in the middle defeats the purpose of the shuttle valve. So I'm wondering if someone substituted that bushing with the hole for a steel ball? But now that I have the full 2500 lb going to each wheel motor, a different problem arises, there is no backflow of hydraulic fluid from the wheel motor. The attached picture shows big big beefy backflow hose disconnected over an oil pan.
Plugging the shuttle valve will make you loosing the release of breaks. No return flow means your counterbalance valve is not working. As counterbalance controls the outlet of the motor. It so happens they I’m currently working on the same thing but on a lot larger machine - 100 ton travel lift. Because of the water in the hydraulic fluid the tiny drain holes were plugged up which in turn led to hydro locking of counterbalance valve poppets resulting in bending and scoring of the plunger that push on the poppet by cross release piston.
Thanks TVA. Actually I completely bypassed the counterbalance valves and the drive brake manifold, and you can see this in the picture if you zoom up and follow the forward drive hose connections. But I did not plumb the parking brake needle valve into that direct line, because I just wanted to see if fluid was passing through the hydraulic motor through the return line. So would it be necessary for the wheel to be spinning in order for fluid to be passing through the drive motor return line?
It’s actually good news, because you have no cross port leakage! If nothing comes out of case drain it is another very good news! Now all you need is cage (release) the breaks! Just take the seat out, the one you unscrewed with Allen wrench, select ball bearing that matches the seat in diameter, drop the ball inside, don’t forget to use thread lock on that seat, and you should be OK!
Okay, so the ball bearing cannot be larger than 1/4 inch in order for it to drop down the cavity, but it must be larger than 5/32 so it does not come back through that retainer bushing that I photographed last night and posted. So I would say 3/16 or 7/32 inch ball bearing? Which would you suggest?
It kinda looks like that bushing is one of two seats for the ball, it looks like ( if I’m not mistaken) first you need to drop the ball, than install the bushing, than tighten that bushing against the shoulder machined in the blocks body. Am I wrong? If I’m right, then you need to select ball that will seal against the chamfer marked by red circles on the picture
Yes TVA, that is right, and that would be a 3/16 inch ball. But I'm curious, what would prevent that ball from blocking the other common outlet for that shuttle valve?
Pressure differential! The side that has more pressure pushes the ball against the seat of the side that don’t have pressure, effectively sealing it from leakage to return circuit.
Thank you, that makes perfect sense!
So would blue Loctite 242 be a good choice for that Allen screw seat? And I'm wondering would it be resistant to Dexron II transmission fluid, which is what this machine has for hydraulic oil?
I use blue lock title in this application of any brand I can get my hands on! It’s important to use some kind of thread lock so the seat will not back out! As of compatibility of thread lock with fluid - you got to read up on it or contact manufacturer or the distributor. I mostly deal with hydraulic oil.