ROLLER & BEARING AS 2008201 - Caterpillar

Illustration 5 g02402117
P-Q Curve for M322D and M322D MH (A) Mode T (Travel mode) at 25.5 bar (370 psi) and 1600 RPM. (B) Mode P (Power mode) at 20.0 bar (290 psi) and 2000 RPM. (C) Mode E (Economy mode) at 14.1 bar (205 psi) and 2000 RPM.The pressure and flow curve for the main pump compares the different flow rates in the three different power modes.Pump flow is on the left and pressure is on the bottom of the chart. Economy Mode and Power Mode are for normal hydraulic operation. Travel Mode is used during travel operation. Power shift pressure is changed for each power mode. In Economy Mode, the power shift pressure is low. The power shift pressure is increased in Power Mode. The power shift pressure is increased further in Travel Mode.Economy Mode is used for light-duty work such as grading or positioning.Power Mode provides maximum hydraulic power and high operating speed. This mode is used for truck loading, trenching, and a hydraulic hammer.On all M300D models, Travel Mode is automatically engaged when the forward or reverse travel pressure switches detect travel. Travel Mode can be preselected on the M322D only. Travel Mode provides maximum speed and drawbar power.The curves show the areas that the horsepower control has control over the pump flow in each power mode. The horsepower control destrokes the pump as either the system pressure increases or the power shift pressure decreases. The rate of destroke closely follows the torque curve of the engine.The pump starts to destroke at pressure points (A1), (B1), and (C1), if the pump is at maximum flow. The pump starts to destroke at pressure points (A2), (B2), and (C2), if the pump is at maximum pressure.If system pressure decreases or the power shift pressure increases, the horsepower control will upstroke the pump when flow conditions are following the curve.The load sensing spool regulates pump flow when system pressure and flow requirements are below the curve for the selected power mode. The area below the curve is the area that is shown in yellow.Note: In the following illustrations, the power shift pressure remains constant, unless an exception is made.Upstroke by Load Sensing Spool
Illustration 6 g02402137
Main Pump Controls (Upstroke by load sensing spool) (1) Load sensing spool (2) Horsepower control spool (3) Main control valve (4) Main relief valve (5) Power shift pressure (6) Lever (7) Actuator piston (8) Maximum angle piston (9) Signal limiter valve (10) Load sensing signal (11) Minimum angle piston (12) Margin pressure spring (13) Slow return check valveThe pump is upstroked and the main pump flow increases under the following conditions:
The flow demand is increased when the pump flow is being controlled by load sensing spool (1). Also, when the flow demand is not on the horsepower curve.
Power shift pressure (5) is increased when the pump flow is being controlled by horsepower control spool (2) .
The system pressure is decreased when the pump flow is being controlled by horsepower control spool (2) .The pump is upstroked