towable backhoe

[jonc00k]

I have an old powerfab towable backhoe that has a problem with the hydraulics.
All the rams are the same size but the one that lifts the dipper arm up into the air is really underpowered, and struggles to lift a bucket of muck up.
Has anyone any ideas what could be causing this. it is fitted with a honda 5.5hp engine and i have tried swapping the pipes around but it made no difference to the operation.

 

[RWolf]

You might post this in the hydraulic section as there is probably more expertise in there. Other than that my guess is if it worked ok before then maybe a fluid flush, filter change and a pressure test. After that it will probably need a cylinder rebuild.

 

[Redneck in training]

If it didn't work before then the cylinder is too small for the load. 5.5 HP engine sounds small. How fast does it move? I just bought similar BH but don't have it home yet so I can't try it out.

 

[J_J]

joncOOK,

Swap the cylinders around, if the dipper arm has the same problem, then it is probably the valve. You can also switch the hoses on the valve to see if there is any change.

 

[Taylortractornut]

joncOOK, I think the cyinder is bypassing or the pump may be worn. Ive done alot of researh on Powerfab machines and talked to several on their strenght. One way to see if its by passing get a bucket of dirt and while the hydraulics are still cool hold your hand on he uper part of the cyilinder tube on the down pressue side of the piston. Then get somone to raise the boom up and hold the lever while its topped out. The cylinder will heat up as the oil heats from the friction and turbulence bypassined the piston. My be yous the pump worn to. Ill post link to towable backhoes I found on the web.
Homemade diggers, homebuilt excavators, towable diggers, backhoe plans

 

[J_J]

Everyone that works on hydraulics, should have a hydraulic test gage assembly, about $25 to $40. Then by placing it in the right position, you can resolve many of your problems.

 

[Brad_Blazer]

If the cylinder is bypassing internally wouldn't it leak down pretty rapidly?

 

[J_J]

If the cylinder is bypassing internally wouldn't it leak down pretty rapidly?

It would depend on how badly it was leaking, and the load.

What you say is true, and the cylinder would never build up the pressure that the cylinder is capabile of.

 

[JoelD]

My towable backhoe had a 5 HP motor and put out almost 3000 psi pressure, did not hit a rock I could not lift, I'm talking 1000lb rocks, the size of the motor is definately not the issue.

Definately a hydraulics problem, would be surprised if it was size of cyl. like these guys are saying more likely a valve or piston seal issue.

Good luck,
Joel