Sumitomo SH75X-3B Hydraulic Excavator Repair Service Manual - PDF DOWNLOAD

Page 334

Control Valve 3. Relief Valve Adjustment (1) Main relief valve

AL

[1] Install an accurate pressure gauge in the entry circuit. [2] Run the pump at its rated rotation rate. [3] Switch the control valve spool and read the pressure gauge at the cylinder stroke end.

TE RN

Switch the spool for the actuator with the overload relief valve set pressure higher than the main relief valve set pressure.

[4] Turn the adjuster clockwise until the required pressure is obtained. The pressure rises 17.8 MPa for one rotation of the adjuster. [5] When the specified pressure is reached, restrain the adjuster so that it does not turn, then tighten the lock nut. (Tightening torque: 27.5 - 31.4 N•m)

IN

[6] Again raise the pressure and check that it reaches the specified pressure. (2) Overload relief valve

CO US N F E ID O E F N TS TI M AL GL : F O OR BA T L H

E

If the set pressure is higher than the main relief valve, replace the assembly for a set relief valve without adjusting the overload relief valve.

[1] Switch the control valve spool and read the pressure gauge at the cylinder stroke end. [2] Turn the adjuster clockwise until the required pressure is obtained. The pressure rises 21.2 MPa for one rotation of the adjuster. [3] When the specified pressure is reached, restrain the adjuster so that it does not turn, then tighten the lock nut. (Tightening torque: 27.5 - 31.4 N•m) [4] Again raise the pressure and check that it reaches the specified pressure.

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ASM-17-23-002EN 13


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