TM 9-2350-256-34-22-22. Adjustment and Load Test of Live Boom Capability.a. Vehicle preparation. Prior to adjusting boom combination control valve (figure 2-7) the following shall beaccomplished:WARNINGTest components (pressure gages, hoses, and fittings) must be capable ofwithstanding a working pressure of 1950 to 2050 psi.Figure 2-6. Counterbalance valve adjusting screw.Step 1 Install pressure gage (NSN 4910-00-766-3355) in boom combination control valve rear gage port (toward rear ofvehicle). Refer to figure 2-7 for location of test gage port.Figure 2-7. Boom combination control valve gage port and adjusting screw.Step 2 If using load cell or calibrated weights, rig a four-part line and extend the boom to an 8-foot reach. Attach loadcell or weights. Load cell must be anchored. If a load cell or weights are not available, place boom in STOWposition. Then block boom in a partially raised position using 2 x 4 wooden blocks on top of each armor airintake cover. (Covers are located at the top rear of the crew compartment.)Step 3 Set engine speed at 1600-1800 rpm.NOTEThe adjustment and load test shall be accomplished with the hydraulic reservoir oiltemperature at 1000F to 1300F.b. Boom combination control valve adjustment. (figure 2-7) Adjust to achieve live boom capability as follows:CAUTIONDo not exceed 1700 psi relief pressure.Step 1 If using load cell or weights, activate boom valve to RETRACT position and use adjusting screw on boomcombination control valve (figure 2-7) to achieve a pull of 50,000 to 55,000 pounds. Turning in a clockwisedirection will increase pressure. If blocking the boom, place the boom operating lever in RETRACT position andboom safety control lever in STOW position. Adjust boom combination control valve rear relief (toward rear ofvehicle) to 1600 psi by turning the adjusting screw (figure 2-7). Turning in clockwise direction will increasepressure.NOTEPressure should be between 1550 and 1650 psi. Do not exceed 1650 psi.Step 2 Verify pressure with locking nut set in locked position and record new setting in Vehicle Log Book.TA171826Change 42-31
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