STRUCTURE, FUNCTION, & MAINTENANCE STANDARD SELF PRESSURE REDUCING VALVE 12 Operation Simultaneous operation with work equipment under heavy load (boom RAISE, etc.) 1. The pump pressure and LS pressure are determined by the pressure of the other work equipment, but the cylinder port pressure of the attachment. When the difference between the pump presure and the cylinder pressure is less than the force of spring (5), then balance of the force acting on valve (1) is as follows. PxA1=A2++LS (A2-A1) +F A1: Cross-sectonal area of diameter D1 A2: Cross-sectional area of diameter D2 F: Force of spring 2.
If the difference between pump pressure P and the cylinder pressure becomes greater than the force of spring (5), poppet (4) is pushed to the right and the passage opens, so the pump passage is connected to the cylinder port through throttle A, chamber G , and passages B and C , and the oil flows to the cylinder port. When this happens, a differential pressure is formed between the upstream and downstream sides of throttle A , and the pressure in the chamber G goes down, so the force pushing valve (1) to the left is reduced. In other words, the area ratio becomes smaller, so valve (1) moves to the right and increases the flow from the pump to the cylinder. 10-90 PC210/240-7K