Tractor Repair: JD 2155 Hydraulic probs., flow control valve, ram check

Question
I have been split the tractor and replaced the return pump . It had shattered the gear. Had a few line leaks. Changed the lines. New filter etc. Now back together, the power steering and the lift are slow and choppy. Seems the more throttle I give the poorer the performance. Can The only thing I didn't change or check wa the main hydraulic pump. the one in the front behind the radiator. I was told that they hardly ever go out. My question is this, can there be air in the hydraulic lines? And how do I bleed them?

Answer
Kenny Private:no Subject:  Question:
I have been split the tractor and replaced the return pump . It had shattered the gear. Had a few line leaks. Changed the lines. New filter etc. Now back together, the power steering and the lift are slow and choppy. Seems the more throttle I give the poorer the performance. Can The only thing I didn't change or check wa the main hydraulic pump. the one in the front behind the radiator. I was told that they hardly ever go out. My question is this, can there be air in the hydraulic lines? And how do I bleed them?

Hi Kenny.
The power steering and the main hydraulic lift system are as you have found 2 different and separate systems.
Not had much to do with JD’s but the smaller pump in front of the radiator is almost certainly the power steering. As this will have the pipes running directly to the steering ram and easy to trace. Suppose there could be an air bubble in this system but it would be unusual did you check the oil levels and the grade of oil of course. Also there could be an air bleed screw on the ram. Check again with the manual, our sponsors have a good selection of manuals.  ---- Iam not on commission.
As to bleeding what does the manual say? And check the filter –is it clean?
Does the main rear hydraulic system have a flow control valve that you can adjust for fast and slow operation? It may be set on slow .
Martin