The relief valve setting is determined at how many times the load?
For load holding and counterbalance valves, a setting pressure of 1.3-1.5 times the highest pressure generated by the load is recommended. This margin prevents the valve from opening unnecessarily during momentary pressure spikes caused by load center shift and dynamic effects, while still leaving an adequate safety margin relative to system pressure.
When choosing the setting pressure you need to find the middle ground between two mistakes.
- Setting too low: The valve opens during dynamic pressure peaks in normal operation. The load drifts uncontrolled and motion becomes jerky and unstable.
- Setting too high: The valve opens late; lowering starts harshly, and shock loading and visible juddering occur in the system. In extreme cases it never opens and locks the function.
Practical method: first raise the load to its maximum value and measure the pressure in the cylinder in that position. The setting is made at 1.3-1.5 times this value. With highly variable loads, moving toward the upper limit is reasonable.
The setting of the main system relief valve is separate from this and is determined by the nominal pressure of the pump/circuit. The load holding valve setting must stay below the main relief valve setting; otherwise the valve can never open.
It is important that measurement and adjustment be done with hot oil, with the system at normal operating temperature. Values taken with cold oil are misleading.
Full coverage of this topic: How Are Manual Hydraulic Levers Controlled Remotely? A Comparison of 6 Methods