Dump Bed Won't Lower

[T_Dilley]

I picked up a 63 One Ton Dump awhile back.
Schwartz PTO Driven Single Cylinder

I have gotten it to raise but it will not lower??

Anybody have any insight into why this could be happening?

The cable on the right is to engage the PTO, the left one raises it when pulled out. I assumed it should lower when pushed back in.
I was never shown how to operate it when I made the purchase, so maybe I'm doing something wrong??

I'm not too familiar with hydraulics or PTO, so any input is appreciated.

[padresag]

just push the hydr lever back in. unless there is a safety dog somewhere to lock it up, which you have to release, you may have to raise the hydraulics to take the pressure off it to release it and let it down. usually those old things will leak down in a while if shut off .ron

[T_Dilley]

Thats what I did was push it back in and it's not lowering.

What should I be looking for to see the safety dog?

It leaks down about a foot over 3 days, I had to crack the line to get it to set back down.

Thanks in advance

[padresag]

you will have to crack a line again then. sound like there is a problem with the valve.some crap in it or something. the valve should work just like you cracking a line, but returns fluid to the reservoir
ron

[RockTonka]

Your doing it right...pull out the left knob to raise, push halfway in to hold, all the way in to lower. Right knob engages/disengages PTO (with clutch in). Check your linkage at the pump/valve to make sure your cables are moving them all the way in/out (no slipping cables/clamps).

And...KEEP YOURSELF CLEAR!!!

Cracking valves/fittings can bring that bed down in a heartbeat...use safety blocks/locks (something) and lots of common sense.

[T_Dilley]

Is the valve in question in the cylinder?

Could it be air in the lines by chance? Or probably something obstructing the flow?

[scotts62]

Sounds like the valve to release the pressure back to reservoir or the cable as stated above. Yep and stay clear!

[RockTonka]

See where your cables pull the bar in/out??? Is it traveling far enough to fully control the valves?

Yea, could be something obstructing flow on the bleed off side...

[bama63]

first from the underside of the truck remove the cable from the lever in pic #4, now move the lever toward the front the truck manually and if the plunger is working properly the bed should lower if not you have a problem within the valve and i repeat and cannot stress this enough "DO THIS WHILE LYING ON YOU BACK UNDER THE TRUCK"

[T_Dilley]

I unhooked the cables..they are at full travel and still nothing.

Must be within the cylinder? Any tips on how to go about fixing that?

I'm clueless on this subject

[61_FL_Apache]

The cylinder is the dumb part of the system. It just moves up and down when fluid is pumped to it. I would think its something in the valve body or the linkage operating it.

something is keeping the fluid from returning to the tank.

The valve is where all the lines come together and the linkage hooks too.

[T_Dilley]

In my case then the 'valve' is the PTO driven pump.

Which is what I'm leaning towards it being after I tinkered with it again today.

Anyone know a good source for hydraulic pump rebuild parts?

[kieth]

Go to a pto warehouse for chelsea dana, if it is one of their pump valve combos then they should have parts for it. If it is not one of their pumps see what brand the bed is, go to a truck body equipment distributor, they may be able to help you finding the parts. you could remove the pump and valve tear them apart and clean them....just pay attention to how it goes back together...........................one last thought-----do you have a restriction in the return line to tank?

[pmkrew]

Some hydraulic systems have an adjustable flow restrictor or one way valve on the outlet side of the system. If there is a restriction blocking or sticking it, that will cause symptoms as you are experiencing also. Are you bleeding the pressure side or return side to get it down now? What is the next item inline if you are bleeding the return side?
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[T_Dilley]

I have to bleed it at the pressure side because all the other fittings are either stripped or going to break when I remove them.