- The main relief valve limits the pressure.
- The main relief valve acts as a makeup valve for the main loop circuit.
The maximum pressure of each loop line of the closed circuit is limited by the main relief valves to 35000 kPa (5076 psi). The pressure is above the low pressure side of the main loop circuit.
Main Relief Function
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| Illustration 1 | g00459561 |
Relief Valve Cross Section (1) Main relief valve. (2) Locking cap. (3) Conical spring. (4) Collar. (5) Spindle. (6) Spring. (7) Collar. | |
Oil from the vibratory pump flows through the relief valve (1) at the passages (A). High pressure oil enters passage (A) and the oil acts on the collars (4) and (7). The force of spring (6) keeps the valve closed until the oil pressure in the high pressure side of the main loop circuit reaches relief pressure. After the relief pressure is reached, the pressure moves the spindle (5) downward while the pressure compresses the spring (6). The relief oil flows from the high pressure side to the low pressure side of the main loop. The oil flows through the gap between the spindle (5) and the collar (7). The arrows show this flow in illustration 1. High pressure oil enters the low pressure side of the main loop circuit until the force of the spring (6) seats the spindle (5) and the collar (7) .
Make Up Function
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| Illustration 2 | g00459758 |
Relief Valve Cross Section (2) Locking cap. (3) Conical spring. (4) Collar. (5) Spindle. (6) Spring. (7) Collar. | |
Oil from the vibratory pump flows through the relief valve (1) at the passages (A). The force of the spring (3) and the oil pressure in passage (A) keep the collar (7) closed. Charge pressure acts on the bottom of collar (7) and the spindle (5). When the oil pressure in passage (A) drops below the charge pressure, collar (7) and the spindle (5) move upward compressing the spring (3) .
The charge oil flows through the gap. The closed loop circuit will be replenished with the makeup oil. The arrows show this flow in illustration 2. Charge oil continues to replenish the low pressure side of the circuit with the make up oil until the pressure in passage (A) becomes greater than the charge pressure.