Servicing hyd on 71 Chevy dump truck

[Dirthog]

I know for a fact that the one that we had would not raise the bed 1/2 way up if you tried to fill it with the body down and we ran it on 3 different trucks!! and there was no pump/ plumbing everything was contained in the cyl it self and ran off a power take off shaft that went into the bottom of the housing

 

[Wis Bang]

Ours had the pump and control valve hanging down from the front of the bed frame w/ a short drive shaft with two hoses to and from the cylinder. It was set up to operate while standing alongside. One lever engauged the PTO [worked the clutch w/ your hand] while the other controlled up/down.

Most of the ones dad had at the city were Galions & Heils set up in a simlilar fashion 'cept the controls were inside to use for spreading abrasives. Prior to hydraulic tailgate spreaders they had a few gas engine ones mounted against the little 'hatch' in the center of the tailgate & they drove around w/ the body partially up to provide gravity flow for salt. They used cinders from Beth Steel for abrasives where the 'helper' rode in the bed spreading them w/ a shovel making 'bands' of cinders every few feet up the hill...that was in the 50's & 60's when men were men and OSHA [really PEOSHA] wasn't even a gleam in Kennedy's eye.....

 

[caseycir]

I've got the same truck, Changed hoses now won't go up! What do you think I did worng? Went threw the pains of jacking up to change hoses and fill cylinder. Now pulling out my hair. Can you help? Mr Walker.. thankyou Caseycircle1

 

[Diamondpilot]

Did you criss cross the hoses? I would try swapping the hoses around.

Chris

 

[Wis Bang]

Did you criss cross the hoses? I would try swapping the hoses around.

Chris

The pump only works in one direction...

 

[Diamondpilot]

The pump only works in one direction...

I meant going to the cylinder. I don't know a thing about these but could have the lift and dump hoses got criss crossed? Then when the pump runs it would be pumping the fluid to the dump side and not lifting.

Just a swag at it.

Chris

 

[caseycir]

The pump only works in one direction...

Hoses are diffrent sizes couldn't cross, I guess I will try to bleed system. As you can see still guessing? After this is figured out I will write a manul. or someone out there may have one.. If so please send me one. I'd say there would be a good market for such a thing....Casey

 

[Wis Bang]

I meant going to the cylinder. I don't know a thing about these but could have the lift and dump hoses got criss crossed? Then when the pump runs it would be pumping the fluid to the dump side and not lifting.

Just a swag at it.

Chris

eggxactly, the pump has to push the piston, reverse the hoses and it won't do that!

 

[AlanB]

If it was like my pump, they use two input shafts, a Clockwise and a CCW, and you select the one for your vehicles input and connect that too the output of the PTO.

Is it possible that you selected the wrong one?

 

[EddieWalker]

I think there isn't enough oil in the cylinder. It takes allot to fill one up again after it's drained, and it's very likely that you got an air bubble in it and thought it was full, but it wasn't. There isn't any way to bleed the hydraulic system, you just run it and let the fluid force the air out of the system. I think you might have to do this a few times and risk over filling it. If that happens, it's easy enough to drain a bit of fluid out. If it's got too much, it won't come down all the way, but it will lift all the way.

I can't imagine how you could mess up a hose replacement. If you take off one hose, then it there is only one way to replace it. Hoses are not directional, and it either has the same or different fittings on each end. Again, it won't matter what direction the hose is.

If nothing else was changed, and it worked before, the only thing that it could be is a lack of fluid. If it didn't work before, then that is a totally different situation that will require tracking down what does work until you find what doesn't work.

Good Luck,
Eddie