HUB 7Y1909 - Caterpillar

Illustration 1 g00021056
P-Q Characteristic Curves
Illustration 2 g00662815
P-Q Characteristic CurvesPower Mode
Engine Speed Dial At Position 10
The power mode is used for heavy work that requires a higher engine speed. Selecting the power mode with the engine speed dial in position 10 will allow regulation of output of the pump. This regulation is accomplished through engine speed and delivery pressure. This regulation provides the maximum available engine horsepower for a work operation.The controller will regulate the pump so that the engine can maintain the target speed. This will give the maximum torque and the maximum horsepower that is available from the engine. As a load on the engine is increased, there is an incremental decrease from the no-load speed: 1980 rpm for 311B, 2080 rpm for 312B, 2300 rpm for 315B, 1970 rpm for 320B, 2120 rpm for 322B, 2180 rpm for 325B and 1960 rpm for 330B. The RPM for the rated speed 1800 rpm for 311B, 1900 rpm for 312B, 2100 rpm for 315B, 1800 rpm for 320B, 1950 rpm for 322B, 2000 rpm for 325B and 1800 rpm for 330B. The rated speed provides the maximum available horsepower. If the load is increased further, the engine speed decreases below the rated speed to the target speed: 1780 rpm for 311B, 1880 rpm for 312B, 2080 rpm for 315B, 1780 rpm for 320B, 1930 rpm for 322B, 1980 rpm for 325B and 1800 rpm for 330B. The controller will regulate the output of the pump so that the engine speed will be maintained at the target speed. While the engine is operating at the target speed, the horsepower of the engine is approximately equal to the horsepower for the rated speed. The engine runs at a speed that is close to the target speed for most of the pressure/flow points on the power mode. The controller will monitor the engine speed through the speed sensor. The controller will send the appropriate signals to the proportional reducing valve in order to maintain the target engine speed. The proportional reducing valve will use the signal to adjust the power shift pressure to the regulator of the pump. Therefore, the power shift pressure will regulate the output of the pump in order to maintain the target engine speed.In the power mode, the power shift pressure will be lower than the pressure in the other two modes. The delivery flow will begin to decrease after the delivery pressure of the pump has reached a higher pressure than the pressure in the other two modes. Therefore, the output of the pump is higher than the pressure of the other two modes. If the available engine horsepower for the main pump decreases due to the addition of an attachment pump or adverse conditions, the main pumps will be regulated in the following manner:
The main pumps are designed to allow the addition of attachment pumps. If an attachment pump is added, the engine can maintain the target speed until a maximum of 30 percent of available engine