Ford 4400 TLB with 753 backhoe need to adjust pressure relief valve

[richwilshaw]

Hi there i am having a problem with my 753 backhoe that is mounted on a Ford 4400 1965 i believe

The dipper cylinder is bent again and i am starting to consider that my pressure relief valve is stuck, dirty or needs adjustment

The only diagram i have of this assembly is on the New Holland parts diagram, i have read somewhere that you take off the acorn nut and had or remove washers to adjust pressure.

So my question is has anybody ever adjusted this valve?

Any help would be appreciated

Thanks, Richwilshaw

 

[J_J]

Do you know the tractor relief pressure, and do you know the BH relief pressure.

Do you have a manual.

Does our BH have a separate pump.

You need a 3000 psi hyd gage to check the pressure.

You can either plug it into a QD, or mount it in a tee in the IN port of the first valve after the pump.

Some relief valves are set by shims, and others are set by adjusting a nut on the relief poppet shaft.

IF it is shim adjusted, go to your dealer for the machine and purchase a relief shim kit. There will be several sizes. Read the instructions.

Should set the relief about 100 psi below the pumps max pressure, or what the manufacturer suggest.

 

[City Farmer]

I have the exact same TLB. The nose pump sends pressure to the BH then PB to the loader. I don't have my service manual in front of me, its at work. I'm pretty sure the BH cylinders have their own relief valves because the relief pressure is different for each cylinder. I can check tomorrow and snap a picture or two of what it looks like. I'm going by a bad memory but I "think" you'll need a 5000 psi gauge to help trouble shoot.

 

[richwilshaw]

Thanks for the help

I have a manual for the tractor but not for the loader backhoe version

The backhoe and loader hydraulics are driven by a pump mounted off the crankshaft pulley

 

[richwilshaw]

Thanks for the help i appreciate it.

 

[City Farmer]

I'm looking at the service manual. @ 165* hydraulic temp. And 1700rpm the system relief should be 2200+\- (50) psi. The main control valve has (4) circuit relief valves for overload protection: 4000psi protects the crowd cyl. piston end. Two relief valves are in the lift cyl. circuit, both set at 3500psi, at each end of the lift cyl. One relief valve, set @ 2350psi, is at the rod end of the bucket circuit. It has 2:1 ratio between the rod & piston end. The rod end should be 4320psi.
I hope this helps but there is a whole lot going on & I highly recommend getting a service manual. There are 18 pages(front & back) of pressure checks on the 750-755 BH.
Good luck, Keep us posted and snap some pictures of your repairs.

 

[richwilshaw]

Thanks City Farmer looks like i will be buying a service manual.

The cylinder is off right now to get rebuilt or straightened at the shop.

The wife says that i am not using the backhoe right, i'm convinced its over pressure bending the cylinder. Either way, she's probably right, she's always right

 

[richwilshaw]

View attachment 353396

 

[richwilshaw]

is this the manual i need to buy?

 

[City Farmer]

That's the same one I have.