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
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 ?
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
I took the main relief cartridge out didn't see anything telling cleaned it.
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 ?
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
Schematics
More hydraulic schematics
https://csapps.jlg.com/OnlineManual...0K/Service_10709790_02-18-05_ANSI_English.pdf service manual download for unit
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.
Ok I wanted to update and thank everyone here for the help and especially tractor mech Craig who helped me with this Lull which had multiple problems from neglect and poor maintenance. Since the forklift had minor hydraulic leaks the old owner let the level get too low he did damage the Vickers G2020 pump there was some wear inside and the plastic seals damaged. Pump is obsolete no parts but you can find seal kits Everything is in the way trying to R&R this 100lb pump you have no leverage to access it I decided on a new after market pump a clone Metaris $1100, JLG has a few new $3500 a rip off IMO same with these scrappers one specializing in Lull wanting $1700 for used. Once installed bee pump had boom functions and could drive it but had very poor weak hydraulics. Lesson learned never assume anything since the old owner had paid a mechanic $3000 to try and fix this machine he told he the mechanic he pulled and checked all relief valves. Turns out secondary relief valve the Gresen which is on the frame tilt, fork tilt transfer boom spool was stuck open had plastic seal material from the pump. After clearing that more functions began working frame tilt and the transfer carriage had full power. Long story short the valve was worn don't bother with Lull or these part resellers they are a complete rip off the Husco 4545B $1900 and the Gresen $900. As long as u get a Husco 4545B they are the same valve factory set different pressures I got one for $50 new and a Gresen for $120 granger. You gotta adjust the pressures anyway as the hydraulic systems wear factory settings useless. The last issue I had the forks wouldn't tilt down only up and stayed that way checked pilot pressure to valve was good 500 psi up and down, took joystick valve apart before that all 4 pistons seals good so that left the inner spool took covers off was sticking. Cleaned spool good and could move it when apart back together everything works perfect. Big project for me to learn as I am used to 12VDC controlled hydraulics this is very complicated system old school using hydraulic pressure for all functions.
Gresen Valve stuck open with seal debris.