120H and 135H Motor Graders Hydraulic and Steering System Caterpillar

Illustration 1	g00871263

For proper relief valve pressure setting, the temperature of the oil should be 49 ± 3°C (120 ± 5°F).

Relief valve pressure setting ... 14200 ± 345 kPa (2060 ± 50 psi)

Oil flow ... 2.0 ± 0.2 L/min (0.53 ± 0.05 US gpm)

Pressure change for one turn of retainer assembly (1) ... 5050 kPa (732 psi)

(2) Torque for nut ... 15 ± 3 N·m (11 ± 2 lb ft)

(3) Torque for cap ... 35 ± 3 N·m (26 ± 2 lb ft)

Note: Hold retainer assembly (1) when you are tightening nut (2) .

(4) Lubricate seals with a thin covering of lubricant that is being sealed.

(5) Spring

Test length ... 31.8 mm (1.25 inch)

Test force ... 222 ± 18 N (50 ± 4 lb)

Free length after test ... 38.1 mm (1.50 inch)

Outside diameter ... 11.9 mm (0.47 inch)

(7) Lubricate the inner diameter of the relief valve body (6) with a thin covering of lubricant that is being sealed.

(8) Lubricate the threads with a thin covering of lubricant that is being sealed.

When you install the relief valve, lubricate seals with a thin covering of lubricant that is being sealed.