John Deere 1520 weak hydraulics

[crackerjack222]

So I have just inherited a JD 1520 utility tractor. It has a bucket with pallet forks. The forks will not lift a table that I estimate weighs about 1000 lbs. I put a gauge on the hydraulic supply line to the bucket control valve and it shows 2000 psi at all times except while the bucket is moving, when it drops momentarily to about 1000 psi. The gauge is at 2000 psi while I am trying to lift the table. I cannot lift the front of the tractor with the bucket. The hydraulics will lift the empty bucket full height.
I have cleaned the screen in the transmission housing and replaced the transmission filter. I have not checked the screen in the hydraulic pump because I did not have a large enough socket with me at the time.
Last week I used it to lift a smaller metal table, probably 600 lbs. it would lift that table about 3' and no more.

The loader is a John Deere 37 which has two single acting lift cylinders and a double acting curl cylinder. The loader control valve is plumbed to the single SCV valve at the rear of the tractor. The SCV valve handle is tied forward with a rope D)

I think the hydraulics are weak, it should be able to lift the table or the front of the tractor. The spec's for the tractor say the hyd pressure should be 2250psi. I plan to increase the pressure but I will probably have to replace some old hoses first. Still, I thought 2000 psi should be enough to lift the table or front of the tractor, NO???
Would a leaking loader piston seal cause what I am seeing? I dont want to start throwing parts at it without some assurance I am fixing the problem.
Does the fact that the hyd pressure is at 2000 psi eliminate a problem with the hydraulic pump?
Any suggestions on what I should do next?

 

[Dave M7040]

So I have just inherited a JD 1520 utility tractor. It has a bucket with pallet forks. The forks will not lift a table that I estimate weighs about 1000 lbs. I put a gauge on the hydraulic supply line to the bucket control valve and it shows 2000 psi at all times except while the bucket is moving, when it drops momentarily to about 1000 psi. The gauge is at 2000 psi while I am trying to lift the table. I cannot lift the front of the tractor with the bucket. The hydraulics will lift the empty bucket full height.
I have cleaned the screen in the transmission housing and replaced the transmission filter. I have not checked the screen in the hydraulic pump because I did not have a large enough socket with me at the time.
Last week I used it to lift a smaller metal table, probably 600 lbs. it would lift that table about 3' and no more.

The loader is a John Deere 37 which has two single acting lift cylinders and a double acting curl cylinder. The loader control valve is plumbed to the single SCV valve at the rear of the tractor. The SCV valve handle is tied forward with a rope D)

I think the hydraulics are weak, it should be able to lift the table or the front of the tractor. The spec's for the tractor say the hyd pressure should be 2250psi. I plan to increase the pressure but I will probably have to replace some old hoses first. Still, I thought 2000 psi should be enough to lift the table or front of the tractor, NO???
Would a leaking loader piston seal cause what I am seeing? I dont want to start throwing parts at it without some assurance I am fixing the problem.
Does the fact that the hyd pressure is at 2000 psi eliminate a problem with the hydraulic pump?
Any suggestions on what I should do next?

Accessories like forks which move the point at which you are going to lift further from the tractor than the front edge of the bucket are going to significantly reduce the amount of weight you can lift.

The simple test for cylinder seal leakage is to leave it elevated with weight in the bucket and see if it gradually lowers.

I will provide more involved test instructions.

Are there one or two cylinders operating the bucket?

A John Deere 1520 has a closed center hydraulic system. This is a more sophisticated system than the open center systems on many tractors. The pump's output is continuously adjusted from nothing to maximum flow based upon the demand for oil. Unless you have special training I advise against adjusting the relief valve as 2,000 psi measured with a gauge, which by design has an error of at least + or - 5% of its full scale (which would be 150 psi) is close enough to spec to be left alone.

Dave M7040

 

[Tx Jim]

JD 37 frt end loader has single acting boom cylinders so therefore has have no means for raising tractor frt tires off the ground or shop floor. Also the boom cylinder shafts which serve as pistons are only 1.75'' in diameter which will severely limit capability of amount weight loader can lift vs other similar size FEL's