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Dan
Dan, Technician
Category: Construction and Road Equipment
Satisfied Customers: 4390
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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Cae 9020 wont rotate and wont drive right track there was a

Customer Question

cae 9020 wont rotate and wont drive right track there was a pump failure
and the pump was replaced it worked for 2 weeks and then started to not drive 1 track and rotate. On the 1st pump lost the pistons and stopped dead.
Never seemed like the pump was right from the beging after had it rebuilt.
I does make allot of noise the stick will move up and down very slowly and the bucket works the right track drives. Really boggs the engine though.
Can you help me I think it needs another pump.
Submitted: 11 months ago.
Category: Construction and Road Equipment
Expert:  Dan replied 11 months ago.

Hi Patrick, My name is***** will be glad to help. I hope that the system was flushed thoroughly after the first pump failure as contamination in the system and valves will not only create further damage to the system components but also cause a new pump to fail from contamination. Check your in tank return filter for metal/debris indicating a failed pump and system contamination. If it was not flushed thoroughly the first time some of this could be from the first failure but if that is the case, the metal and contamination will also be lodged in the valves, cylinders, drive motors, cylinders, and other system components which will all need to be flushed and inspected for scoring and damage. Let me know

Customer: replied 11 months ago.
he took the tank off and cleaned it out real good changed the filters. I pulled out the return filter only saw a very small
metal chip there only 1 chip. I wonder why the right track wont turn and the house wont rotate though. He said if he shut the motor off and restart it would then work for awhile. but not very well pump sounds as though it is screeching. It has a piston style pump so they either work or not. Does it have a charge pump on it?
Expert:  Dan replied 11 months ago.

It has a variable displacement pump and consists of two main pumps coupled together. Pilot pressure is your control pressure to shift the spools in the main control valve when a function is operated and also signals the pumps for full stoke when multiple functions are needed. the noisy pump is a bad sign but whoever told you they either work or they don't gave you wrong information. Either way, you could have a stuck or failed piston in the pump causing the swash plate to be stuck in a certain position. Pull the circuit relief valve cartridges for those functions and also the main lines from the valve into the swing motor and into the right track and check the ports for metal

Customer: replied 11 months ago.
where do i locate the circuit relief valve cartridges is there a schematic that you can send me.
Dosent seem like they are engaging though. where dose the pilot pressure come from the main pump?
Expert:  Dan replied 11 months ago.

The circuit relief valves are threaded into the main control valves behind the base of the boom where the main hydraulic lines come from. the are round cylindrical cartridges with an adjusting screw and lock nut on the top of them to adjust pressures. Do not disturb the adjustments but remove the cartridge as an assembly and check for debris and damaged o rings. Be sure to bleed the residual pressure from the system and vent the tank pressure before removing a relief cartridge. You will lose oil so a drain pan will be necessary

Expert:  Dan replied 11 months ago.

Pilot pressure comes from the small pilot pump bolted to the end of the main pump assembly. It is a gear type pump and pilot pressure should be around 566 PSI.... The main pressure from the main pumps is 4263 psi

Expert:  Dan replied 11 months ago.

Hi Patrick, did you get this resolved?

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