LULL 844C-42 no hydraulic boom etc functions

[Roadoil]

Hello.
I have a LULL 844C-42 MAR96 W16 P18- 282

No hydraulic boom functions or tilt etc.

Steering works and crab functions.

Just bought the machine owner paid a mechanic $3000 he spent 20 plus hours checking relief valves etc told owner time to start throwing parts at it beginning with main pump owner bought new extreme I own it now.


Machine runs fine

I have cleaned main relief valve that's it.

Pump 1 O pressure at port

Pump 2 starts O pressure if I rev engine to 1300 rpm I get 500 psi that's it.

Steering pressure will be at 0 when. I turn wheel goes to 2200 psi

Pilot 0 pressure

Thanks

 

[Vetech63]

That looks like the older style vane pump. You need to run a flowmeter test on it and see what you have to work with. Doing anything else before a flow test is just chasing ghosts.

 

[Roadoil]

That looks like the older style vane pump. You need to run a flowmeter test on it and see what you have to work with. Doing anything else before a flow test is just chasing ghosts.

Ok I don't have a flow meter it's a gear type pump. Any other ways to test without flow meter ?

 

[Vetech63]

With what has already been done a flow meter test is needed. Some dealer in your area should be able to perform the test for you. The symptoms you have posted tell me you have weak pump flow……..bad pump or bad bypass…..you need to know which it is to move in the right direction

 

[Roadoil]

With what has already been done a flow meter test is needed. Some dealer in your area should be able to perform the test for you. The symptoms you have posted tell me you have weak pump flow……..bad pump or bad bypass…..you need to know which it is to move in the right direction

Ok that's what I am thinking also bad pump

 

[Roadoil]

With what has already been done a flow meter test is needed. Some dealer in your area should be able to perform the test for you. The symptoms you have posted tell me you have weak pump flow……..bad pump or bad bypass…..you need to know which it is to move in the right direction

I took the main relief cartridge out didn't see anything telling cleaned it.

 

[Roadoil]

With what has already been done a flow meter test is needed. Some dealer in your area should be able to perform the test for you. The symptoms you have posted tell me you have weak pump flow……..bad pump or bad bypass…..you need to know which it is to move in the right direction

I don't think u can get rebuild parts for these Vickers G2020 pumps any more are they worth rebuilding or just get a new alternative same clone pump ?

 

[Vetech63]

If you need a pump, get the numbers off the pump tag and contact www.flinthyd.com

 

[Roadoil]

If you need a pump, get the numbers off the pump tag and contact www.flinthyd.com

Ok I will check with them found a clone that can be made $1100. JLG wants $3500

 

[Roadoil]

Schematics

 

[Roadoil]

More hydraulic schematics

 

[Roadoil]

https://csapps.jlg.com/OnlineManual...0K/Service_10709790_02-18-05_ANSI_English.pdf


service manual download for unit

 

[tractormech]

You have steering pressure on demand and the chance that the other section of the pump is bad is slim at best. Possibly worn some, but not bad. You have a pilot pressure issue. There's no pilot pressure, therefore the joysticks won't work. The pump has no load put on it, therefore it reads 0 pressure. You have a control manifold system. That block you posted is the control manifold. In the top towards the rear is the pilot directional valve marked "PD", the one with the hose hooked to the top and the furthest back is the pressure reducing valve, "PR". Both work together and allow 450 PSI to the joystick circuit. Remove those and see if the O-rings are damaged. If they look good you may have one of the valves stuck and dumping back to the tank. Does the machine cycle just sitting? Do you hear anything that sounds like it's kicking in and out? Do you hear any hissing noise at the block? After it runs a few minutes does one part feel warmer than the rest of the block? Both can indicate internal leakage in the manifold. Let us know.

 

[Roadoil]

You have steering pressure on demand and the chance that the other section of the pump is bad is slim at best. Possibly worn some, but not bad. You have a pilot pressure issue. There's no pilot pressure, therefore the joysticks won't work. The pump has no load put on it, therefore it reads 0 pressure. You have a control manifold system. That block you posted is the control manifold. In the top towards the rear is the pilot directional valve marked "PD", the one with the hose hooked to the top and the furthest back is the pressure reducing valve, "PR". Both work together and allow 450 PSI to the joystick circuit. Remove those and see if the O-rings are damaged. If they look good you may have one of the valves stuck and dumping back to the tank. Does the machine cycle just sitting? Do you hear anything that sounds like it's kicking in and out? Do you hear any hissing noise at the block? After it runs a few minutes does one part feel warmer than the rest of the block? Both can indicate internal leakage in the manifold. Let us know.

I'll check temps I don't hear any hissing noises.