Loader Valve Relief Pressure Adjustment

abwehrly42 · May 17, 2023

This loader valve was originally on a Steiner LD300 attachment.

Where would I find the adjustment for the relief pressure? I don't want to start pulling caps and having springs and spools popping out.

oldnslo · May 17, 2023

I suspect under the cap with 2000 or 3000 marking in picture 201321. Suspect it is also shims to adjust.

abwehrly42 · May 18, 2023

Thank you oldnslo. This circuit continues to the 3 point. Since there is another relief valve in the system can I disable this one? Add enough shims so it would never open.

WranglerX · May 18, 2023

abwehrly42 said:
Thank you oldnslo. This circuit continues to the 3 point. Since there is another relief valve in the system can I disable this one? Add enough shims so it would never open.

Generally the first valve body (relief valve) in system controls system pressure... If you try to use downstream pressure relief, it subjects any valve body (hydraulics) before relief valve to full pump pressures....

rScotty · May 18, 2023

abwehrly42 said:
Thank you oldnslo. This circuit continues to the 3 point. Since there is another relief valve in the system can I disable this one? Add enough shims so it would never open.

Why? I don't understand the advantage in doing that.
rScotty

abwehrly42 · May 18, 2023

My understanding is that my hydraulic pump produces 2200psi (YM1500 Hydraulic pump capacity - Yanmar Tractor Support Message Board), in which case I would want the loader to receive full pump pressure. Or have I misunderstood and the pump is limited to 2200psi by the relief valve?

oldnslo · May 18, 2023

Ab
The very first valve in the circuit must be the main system relief. If this add on valve is down stream of the main relief it does not matter if you block it or not. If this new valve was installed before the original factory relief it must be set to factory specified pressure since it is now your main system relief.

rScotty · May 18, 2023

abwehrly42 said:
My understanding is that my hydraulic pump produces 2200psi (YM1500 Hydraulic pump capacity - Yanmar Tractor Support Message Board), in which case I would want the loader to receive full pump pressure. Or have I misunderstood and the pump is limited to 2200psi by the relief valve?

The system pressure is limited by the relief valve. The pump itself is a positive displacerment type & can make tremendous pressure. Without a pressure limiting relief valve, even that elderly YM1500 hydraulic pump would make enough pressure to break things.

I don't know if the YM1500 has a system relief valve right at the pump and a secondary one at the loader control valve, but many tractors do. The relief valve in the directional control valve can also have an additional function. It has to deal with pressure spikes in the cylinders and lines when the loader hits something or drops suddenly. Same for the 3pt relief.