 | |
| Illustration 1 | g00817815 |
The charging pump relief valve is connected to the output side of the charging pump past the swing filter. The relief valve is adjustable. The relief valve is factory set at 2000 to 2200 kPa (290 to 320 psi). The released oil is used to cool the swing pump. After the released oil passes through the pump case drain, the oil goes to the hydraulic tank.
The crossover relief valve and the pressure cutoff valve are connected to either side of the high pressure output on the pump. The crossover relief valves are used to limit system pressure. The crossover relief valves also function as check valves. The pressure cutoff valve returns oil from the pump outlet to the pump inlet through the high pressure spring and the poppet valve.
The cutoff valve is an adjustable valve. The relief valve poppet receives the high pressure through a shuttle valve from either side of the pump output. The poppet shifts the cutoff spool in order to release the control pressure to the drain. Reduced control pressure reduces the pump swashplate angle in order to decrease the flow to a minimum while the pressure is kept at the maximum of the relief valve setting.
Reference: Refer to Testing And Adjusting, RENR1180, Testing And Adjusting, RENR1181, Testing And Adjusting, RENR1182 or Testing And Adjusting, RENR1183 for the swing line relief valve pressure specifications and the swing cutoff valve pressure specifications.
The effective pressure on the swing motor is the difference between the high pressure side and low pressure side.
Swing Charge Pump and Filter
 | |
| Illustration 2 | g00531827 |
Pump compartment (1) Swing filter | |
The charging pump is a gear type pump that is driven from the swing pump drive. The oil inlet to the pump is from the suction line of the main pump. The outlet is connected to the externally mounted swing circuit filter and to the relief valve manifold.