PTO Pump on Backhoe

[Anonymous-0]

I bought a Arps 3 point backhoe at a sale. It came with a Prince PTO pump. When I hooked the pump up to the hoe it would viberate and built up heat very fast, almost melted the return line. I hooked the hoe up to the tractor hydraulics and it worked fine, slow unless tractor was at hi rpms. I put the pump on the tractor and ran the pressure line back into the reserivor, no viberation or heat build up. It seems the pump is too big for the hoe. Is there some way to make that pump work with that hoe.

 

[Bob]

WHAT speed is your PTO... 540 or 1000? Did someone by any chance take a pump intended for 540 RPM's and put a coupler on it to fit a 1000 RPM PTO and is that what you are running it on?

If it's just simply that the pump is too big, slowing down the engine should reduce the flow to what the 'hoe can handle, so long as the engine has enough HP at the lower RPM's to keep up with the load.

 

[Doug in IL]

I don't think that some of those pumps have a built in relief valve. You must have a relief valve. Maybe it is on the backhoe and it isn't plumbed correctly, or it is stuck? When you are hooking the pressure side of the pump up to flow back into the reservoir, the pump is developing little to no pressure. So a relief valve is not really in the equation. It is basically just circulating the oil. If those pumps DO have a built in relief valve, then it is probably stuck. Just guessing, wish I could see the unit.

 

[Doug in IL]

Just one more thing. When you run the backhoe off the tractor's hydrualic system, the tractor is providing the relief valve.

 

[Bob]

ASSUMING the 'hoe has an open center valve the oil should just simply be flowing through the valve and returning to the tank, so long as the pump's capacity isn't WAY more than the rated flow of the valve (and hoses).

The relief valve isn't even in the picture 'til the 'hoe is overloaded or a valve is held in the "operate" position after it's cylinder has reached the end of it's stroke.

 

[Doug in IL]

Some of those Prince tractor PTO pumps are 23 gal per minute at 540 rpm and 40 gal per minute at 1000 rpm. The compact series Prince control valves, which are likely on this small backhoe, are 8 gal per minute valves. I believe the relief valve is most certianly in that equation. The original poster probably has no idea what pump he has. Some of those pumps are only 7.1 gal per minute. I really think his problem is a relief problem on the backhoe. That's why it works fine on the tractor. Can't really be much else. From what he describes, it sounds like the pto pump is deadheaded or nearly so. Could be the relief is plumbed wrong or the relief drain port is plugged off. I'll be interested to see what he finds out.

 

[Anonymous-0]

Thanks for your responses. The pump doesn't have a relief valve, pressure port on the pump is 3/4, to 1/2 in hose to the hoe then 3/8 hoses to armes and bucket. PTO is 540 and slowing engine down doesn't seem to help and I don't see a relief valve on the hoe. Manual for the hoe calls for 10 gal per min. Prince pump I think is more than twice that. Maybe the pump is just too big.

 

[Anonymous-0]

Generally the valves provide the pressure relief.

3/8 seems small for 23 GPM.

I'd put a 3/4 tee in at the pump to a seperate pressure relief valve that dumps the excess to the hyd tank.

This will solve the pressure relief issue.

 

[Doug in IL]

The pump could be too big. Those Prince PTO pumps are available in 7, 11, 17, and 23 gal per minute sizes. You probably need the 11 gal pump. If you happen to have a 23 gal pump, that could well be the problem.

 

[Bob]

If idling it way down doesn't help, neither will the smaller pump as even the 23 GPM pump would be down below 10 GPM's at idle.

 

[JDseller]

If your backhoe is setup for a closed center hydraulic tractor. Then when you hook up the open center Prince pump you are stalling it out. The valves are changeable back and forth, open center to closed center. You need to check out a manual for your model of backhoe.