Lift trucks

[Dropout]

Hi All.

I have two new (to me anyway) Caterpillar M50D electric lift trucks. Both of them have sticky valves and it looks like the hydraulic oil filters were last changed in the 1990's.

What would be the best oil to use in these to try to unstick the valves before I decide to tear down the hydraulics?

Are there better ways to deal with filtration than the OE filter?

 

[Steve S]

Valve spools sticking? or are the switches that turn the pump motor on and off are sticking?

 

[Dropout]

Sorry, spool valve.

 

[Steve S]

If the linkage is not rusty etc there is a centering spring on the spool ,these springs can break. The springs are on the spools internally. Does the valve assembly leak?

 

[Dropout]

The valve does not leak externally.

The symptom is that the forks lift slowly but if the steering wheel is moved they speed up. If the steering wheel is held in the right position the forks will operate normally. I suspect there is some bypass happening through the steering control valve. The unit sat for several months before I got it.

I haven't been able to find a repair manual for this, unless I go to Caterpillar and pay $400.00 plus, so I don't have the hydraulic diagram.

 

[Steve S]

Call the cat repair person. I could be a couple of things.

 

[bruce381]

Good advice but at the least you could change filters and oil to whatver vis grade is recomended that may remove enough debris and gunk that could help.
bruce

 

[Steve S]

Does the hyd pump speed up when the steer wheel is turned? Some eletric forklifts are way too high tech as most stuff is ,which makes it hard to diagnose with out a svs manual or experience with them.