Operation - Section 30 OM3070 Page 30-16 Operating Instructions DISABLED TRUCK DUMPING PROCEDURE b. Remove the cap from the hoist pilot valve relief valve located in the hydraulics compo- nents cabinet behind the cab. While counting the number of turns, slowly screw relief valve adjustment screw clockwise until it bottoms. Sometimes it is necessary to dump a load from the body of a truck when the hoist system is inoperable. The following instructions describe the use of a "good" truck to provide the hydraulic power required to raise the body of the "disabled" truck to dump the load. 5. Repeat Step 4 to dump the disabled truck.
Lowering the Body In the example below, Figure 30-3 illustrates a typical hookup from the good truck. The disabled truck may be another Model 730E or a different Komatsu model. 6. Place the hoist lever of the good truck in FLOAT to lower the body. If necessary, momentarily place the hoist control in POWER UP until the body is able to descend in FLOAT. DO NOT accelerate the engine. Hookup 7. After the body is lowered, shut the engine off. Bleed the hydraulic system of pressure and dis- connect the hoses. Ensure there is an adequate, clear area to dump the loaded body. When the good truck is in position, shut the engine off and allow the hydraulic system to bleed down.
Ensure pressure has bled off before connecting hoses. 8. Reduce power down relief valve pressure to normal on the good truck by turning the adjust- ment counterclockwise the same number of turns as required in Step 4 b. 1. With the good truck parked as close as possible to the disabled truck, attach a hose from the power up quick disconnect (1, Figure 30-3) to the power down circuit of the disabled truck. The hose must be rated to withstand 17 237 kPa (2,500 psi) or greater pressure. 9. Check power down relief pressure per instruc- tions in the shop manual, Section L, Hydraulic Check-Out Procedure. Check the hydraulic tank oil level. NOTE:
The power down circuit will use a smaller diameter hose (tube) than the power up circuit. 2. Connect another hose from power down quick disconnect (2) to the power up circuit of the dis- abled truck. NOTE: If both trucks are a model 730E, the hoses will be installed at the quick disconnects shown in Figure 30-3 and will be crossed when connected. Raising the Body 3. On the disabled truck, move the hoist control lever to POWER UP and then release it to place the hoist pilot valve in the HOLD position. Leave in this position during entire procedure. 4. Start the engine on the good truck.
Place the hoist control in the POWER DOWN position and increase engine rpm to high idle to dump the disabled truck. If the body of the disabled truck fails to raise, increase the good truck power down relief pressure as follows: FIGURE 30-4. PUMP MODULE, HOSE HOOKUP 1. Power Up Quick Disconnect (Connect to power down circuit of disabled truck.) 2. Power Down Quick Disconnect (Connect to power up circuit of disabled truck.) a. Shut the engine off and allow the hydraulic system to bleed down.