etd66ss
Senior Member
I have an old Pettibone Extendo 88 forklift that I am working on some hydraulic issues this winter. I have rebuilt the Char-Lynn SCU unit, but have yet to be able to test it out.
When I got the machine the steering worked, but the SCU whined & growled like crazy, even if I wasn't touching the steering wheel. When I took it apart, I didn't see any internal damage, here are some pics:
http://imgur.com/ZyvyCo3
http://imgur.com/MTYTbTH
http://imgur.com/B7yaN2Q
http://imgur.com/FFNKLUv
http://imgur.com/QH6S5UQ
http://imgur.com/Yd2ySx7
One thing I noticed when I was disassembling is that there was some wear on the endplate where the rotary valve makes contact. The endplay of the rotary vale was almost 0.012". That seemed to me like oil under pressure could be bypassing that clearance and causing the noise? I ground and lapped various parts to get them square and free of any wear marks, when I was done the endplay was about 0.003". I'm hoping that is enough clearance so when the unit heats up and thermal growth sets in, the unit doesn't lock up.
If it turns out this unit still doesn't work properly and still whines etc, I'd like to replace it with a new Eaton unit. The problem is, I don't know what model/size Eaton to replace it with. I don't know the GPM of this unit.
I'm wondering if anyone has any experience with hydraulic SCU's and could tell me what the replacement is for my old Char-Lynn unit?
The Model number is UM3-01, the S/N is 1285-
When I got the machine the steering worked, but the SCU whined & growled like crazy, even if I wasn't touching the steering wheel. When I took it apart, I didn't see any internal damage, here are some pics:
http://imgur.com/ZyvyCo3
http://imgur.com/MTYTbTH
http://imgur.com/B7yaN2Q
http://imgur.com/FFNKLUv
http://imgur.com/QH6S5UQ
http://imgur.com/Yd2ySx7
One thing I noticed when I was disassembling is that there was some wear on the endplate where the rotary valve makes contact. The endplay of the rotary vale was almost 0.012". That seemed to me like oil under pressure could be bypassing that clearance and causing the noise? I ground and lapped various parts to get them square and free of any wear marks, when I was done the endplay was about 0.003". I'm hoping that is enough clearance so when the unit heats up and thermal growth sets in, the unit doesn't lock up.
If it turns out this unit still doesn't work properly and still whines etc, I'd like to replace it with a new Eaton unit. The problem is, I don't know what model/size Eaton to replace it with. I don't know the GPM of this unit.
I'm wondering if anyone has any experience with hydraulic SCU's and could tell me what the replacement is for my old Char-Lynn unit?
The Model number is UM3-01, the S/N is 1285-