bus-junkie
Member
Where is this block located on your machine?
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Boom lift Drive Wheels torque fade
- Thread starter Ronray
- Start date
Diagram shows pressure reducing valve only on one inlet port of control valve, look on the back of your DCV for the spool end cap different than the one on the front and kinda looking like bus-junkie showed on his picture. The spool end cap on your picture looks like regular hydraulic pilot control cap.
1200psi is way too low! Should be closer to 3000 psi. The question is where do you loose your pressure?! There’s several places, I would cap outlet of counterbalance/flow divider block and check the pressure. If pressure would go up - then you loosing pressure at your motors!
1200psi is way too low! Should be closer to 3000 psi. The question is where do you loose your pressure?! There’s several places, I would cap outlet of counterbalance/flow divider block and check the pressure. If pressure would go up - then you loosing pressure at your motors!
Last edited:
bus-junkie
Member
TVA, what is DCV?
If you look closely at my picture of the pressure relief valve block, you will see that it is bolted alongside a larger valve block with the same bolts. I think it is strange that both hoses from the boom extension proportional valve also go into this pressure relief valve (see picture) which seems to be the only pressure relief valve for the entire system. I only confirmed that this was the pressure relief valve by looking at the hydraulic schematic and hydraulic hose kit pages in my PDF service and parts manual below and also the parts list diagram in my above post.
I also think it's odd that in the hose diagram below and on my machine, it appears that the pressure relief valve exit hose going back to the holding tank goes through the emergency pump?
Like yourself bus, I had 2700 lb of pressure on the portional valve bank, but 1200 lb on the wheel motor gauge.
If you look closely at my picture of the pressure relief valve block, you will see that it is bolted alongside a larger valve block with the same bolts. I think it is strange that both hoses from the boom extension proportional valve also go into this pressure relief valve (see picture) which seems to be the only pressure relief valve for the entire system. I only confirmed that this was the pressure relief valve by looking at the hydraulic schematic and hydraulic hose kit pages in my PDF service and parts manual below and also the parts list diagram in my above post.
I also think it's odd that in the hose diagram below and on my machine, it appears that the pressure relief valve exit hose going back to the holding tank goes through the emergency pump?
Like yourself bus, I had 2700 lb of pressure on the portional valve bank, but 1200 lb on the wheel motor gauge.
DCV is Directional Control Valve. The one you have the picture of.
TVA, I think I may be confusing the DVC with the flow diverter valve in the wheel motor valve manifold. Would you be able to Circle the part you are talking about in red and post it here? You're not talking about the valve block that the pressure relief valve block is bolted together with the same bolts, are you?
The main relief ( extreme left, on the bottom) is a safety RELIEF ( meaning it’s opens at set pressure and drains to tank) is a safety feature and regulates pressure in “pressure gallery” of DVC, but each section can have its own PRESSURE REDUCING valve ( closes passage at set pressure), it’s own flow reducer, port reliefs, load check, regeneration, and etc. valves. I need to see your diagram to know what’s in it. Yours probably using fixed displacement pump and it does have relief valve ( I can see it on the picture).
Ronrays diagram doesn’t show main relief probably because it’s variable displacement pressure compensated pump.
Yes it will, but you can have normal pressure in Main Control Valve gallery, but your drive section can have lower pressure if the pressure reducing valve in that section is bad or miss adjusted!
Looks like the one on top is a external port relief for boom extension cylinder.
TVA, okay would the pressure reducing valve be the one in this picture with the Allen wrench inserted in this picture on the lift function? I noticed that the Allen screws on all of the functions are in different positions. So I assume this would be because they all have different reduced pressure settings?
Not 100% sure, but I think that’s where the pilot control hose supposed to connect to!
TVA, my pump is a variable displacement pump 2-32 cid. Does the 2 signify two pistons? If a variable displacement pump does not have a main pressure relief valve , then the pressure gauge for the main galley should read 1200 PSI, just like the pressure gauge for the wheel motors when I engage the drive function? FYI, when I engage the other functions on the machine, like the boom lift for example, the main galley pressure gauge reads 2700 lb.
Does the hydraulic hose kit diagram I posted earlier give any clues? Is the relief valve in that diagram, upper right-hand side, just for the boom extension function and not for the entire system?
Does the hydraulic hose kit diagram I posted earlier give any clues? Is the relief valve in that diagram, upper right-hand side, just for the boom extension function and not for the entire system?
The designations on hose diagram is hard to read on my end, if pressure relief has one port connected to extension cylinder and other to tank then it is extension cylinder port relief valve.
If your main pressure drops to 1200 together with your drive pressure then it caused by leakage ( bypassing ) somewhere.
Cap the hoses that go to high speed cylinder and see if pressure will go up. If it not that cap the hoses that go to motors and check the pressure.
