BOOM AS 3172486 - Caterpillar

Illustration 1 g00301278
Main Control Valve (1) Rod end line relief valve for the tilt cylinder. (2) Head end line relief valve for the auxiliary cylinder. (3) Head end line relief valve for the tilt cylinder. (4) Rod end line relief valve for the auxiliary cylinder. (5) Main relief valve.
Start the engine. Run the engine at high idle. Operate the control levers and move all the cylinders in order to increase the temperature of the hydraulic oil to normal operating temperature.
Illustration 2 g00298585
Jack Stands (Typical Example)
To improve access to the main control valve, rest the lift arms or the attachments on a jack stand.
Stop the engine.
Remove the loader tower access panel that is over the main control valve in order to access the line relief valves.
Move the control levers through the full range of travel several times. This will relieve any pressure that may be present in the implement hydraulic system.
Push on the hydraulic tank breaker relief valve in order to relieve the pressure in the hydraulic oil tank. Push in the plunger until all pressure is released from the hydraulic oil tank.
Illustration 3 g00714061
Area of the Loader Tower (6) Main hydraulic system pressure tap.
Install an 8T-0859 Pressure Gauge from an 8T-5320 Hydraulic Test Group on the pressure tap for the auxiliary cylinder or on the pressure tap for the tilt cylinder. Install a pressure gauge on the pressure tap for the main hydraulic system which is shown in Illustration 3.
Table 2
Settings for Line Relief Valve in kPa (psi)    
    Tilt     Auxiliary    
Head End     22750 (3300)     20700 (3000)    
Rod End     22750 (3300)     12400 (1800)    
Head End (Logging)     26000 (3770)        
Rod End (Logging)     20700 (3000)        
Table 3
Settings for Main Relief Valve in kPa (psi)    
Standard     20700 (3000)    
Logging     19000 (2750)    
Start the engine.
Illustration 4 g00315870
Main Relief Valve (6) Locknut (7) Adjusting screw
Compare the pressure gauge readings with the specifications in Tables 2 and 3.
If the main relief valve setting is lower than the line relief valve setting, it will be necessary to temporarily increase the main relief valve setting.
Perform Steps 12 through 14 if the main relief valve pressure setting is too low. If the main relief valve setting is high enough, then proceed to Step 15 for the relief valves for the tilt lines, or proceed to Step 16 for setting the relief valves for the auxiliary lines.
Leave the engine running. Loosen locknut (6) .
Turn adjusting screw (7) clockwise for a quarter turn in order to increase the pressure setting by 1310 kPa (190 psi). Likewise, turn adjusting screw (7) counterclockwise in order to decrease the pressure setting.
After adjusting screw (7) is turned for an adjustment, tighten locknut (6) to a torque of 50 7 N m (37 5 lb ft). Return to Steps 9 and 10.Note: In the following steps, do not stroke the tilt control lever or the auxiliary control lever for more than five