Hydraulic pump on JD 310a

[onalaskahoe]

If anyone out there has a John Deere 310a Backhoe, could you send or post any photos or tell me where the destrole pressure adjustment screw is on your tractor.( top- bottow- side- left or right.)

I wonder if my pump head might be assembled incorrectly?

 

[JDemaris]

It goes on top, but did not come as standard equipment - so there might just be a small hex-shaped plug there instead. It's directly opposite the stroke-control adjuster on the other end of the pump (at the bottom). The T-handle, when screwed in, puts pressure against that stroke-control-valve and forces it open.

If your pump was upside down, then the T-handle would be at the bottom, and the pressure-adjuster screw would be on top. That is very unlikely, but some older Deere ag. tractors did have the pumps mounted that way.

 

[twopop]

the prssure adjustment screw is located on the bottom of the pump.there will be a 1/2 inch nut around a allen head scrue.the destroke valve is located under this.some people have added manual destroker which goes into the top of the pump.if you wish to take out the valve it must be removed from the bottom and the plug or destorker must be removed at the top and a punch used thru the top hole to knock out the valve

 

[JDemaris]

You cannot put the pump-head on wrong and have a working pump. It won't pump oil that way since there are two small oil ports that have to line up and it only goes on one way.

Here's a picture of the same pump on a green tractor. Pretty much the same as what your's has. The T-handle on top is the screw that turns off the hydraulics. Lined up with it, all the way on the bottom is an adjuster screw with a jam-nut that takes a 3/4 wrench. The screw can either be an internal hex Allen type drive - or some older oddballs have a straight screwdriver slot instead. It maintains spring pressure on the float-control valve that maintains standy pressure around 2200 PSI. If you take the adjuster assembly out, the stroke control valve will fall right out. The seat, however, is a light press fit into the housing.

As I said before, some early 1960s ag. tractors DID have the pump "upside down" with the adjuster on top, and the shut-off port on the bottom.

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[onalaskahoe]

Thank you to all, i will continue to try and find out why I have slow and weak haydraulics. I do get 2200psi with the output capped, so I will look for the leak downstream.
I still think it might be with the priority valve.
People say that they can cause slow and weak hydraulics, not sure how but i will check it.

 

[onalaskahoe]

Hello Jonathan

I pulled the priority valve today and found that the spring loaded valve had been floating and has worn down and is now half missing, this was allowing a lot of oil to pass through and then dump back into the trans case through the 1/4 in hole at the back of the valve. I have made a new valve tip and reinstalled it. the pressure is better but not good yet.
My question now is !!!!! How do I set the load on the spring so that the actuating pressure is correct? The spring may not be the right one and might be too soft, allowing the oil to plow by at a lower pressure and making the loader not work as it should.

what do you think??

 

[buickanddeere]

I would go to the dealer and purchase new parts for the priority valve.