TRACK GP 3913927 - Caterpillar

Upstroke
Illustration 3 g00458572
Implement Pump Regulator Control ValveUpstroke (1) Warm-up solenoid valve (2) Implement control valve (3) Power shift pressure signal (4) Constant horsepower control spool (5) Lever (6) Actuator piston (7) Load sensing signal pressure line (8) Maximum angle servo (9) Swashplate (10) Load sensing control spool (11) Minimum angle servo (12) Horsepower control adjustment (13) Slow return check valve and orifice (14) M1 port pressureThe following three conditions can cause an increase in flow from the main pumps:
An increase in the load sensing signal pressure
An increase in the power shift pressure
A decrease in the pump discharge pressureThe load sensing signal pressure plus the spring force acts on the right end of load sensing control spool (10). The pump output pressure acts on the left end of load sensing control spool (10). The forces on the ends of load sensing control spool (10) are in balance.When the load sensing signal pressure increases, the load sensing control spool (10) moves to the left. Moving load sensing control spool (10) to the left opens the passage from slow return check valve and orifice (13) to the tank.When the pump is in balance, constant horsepower control spool (4) is positioned so that the passage to slow return and check valve (13) is slightly open to the passage to minimum angle servo (11). Since these passages are connected, load sensing control spool (10) shifts to the left. When load sensing control spool (10) moves to the left, the oil in minimum angle servo (11) returns to the tank through slow return check valve and orifice (13) and through load sensing control spool (10) .When minimum angle servo (11) is open to the tank, the pump output pressure acts on maximum angle servo (8). Maximum angle servo (8) rotates swashplate (9) counterclockwise. Rotating swashplate (9) counterclockwise upstrokes the pump. As maximum angle servo (8) shifts left, the mechanical advantage of actuator piston (6) against lever (5) increases and the lever rotates clockwise. When lever (5) rotates clockwise, constant horsepower control spool (4) shifts to the right. Shifting constant horsepower control spool (4) to the right restricts the oil in minimum angle servo (11) from returning to the tank. Restricting the oil in minimum angle servo (11) from returning to the tank stops swashplate (9) from moving.When the implement circuits or travel circuits approach full operation and the difference between the load sensing signal pressure and the pump output pressure decrease below the margin pressure. With the pressures below the margin pressure, load sensing control spool (10) becomes fully shifted to the left. When load sensing control spool (10) is fully shifted to the left the load sensing control spool is disabled. When load sensing control spool (10) is disabled, constant horsepower control spool (4) regulates pump flow. Constant horsepower control spool (4) regulates pump flow by pressurizing the oil in minimum angle servo (11) or returning oil to the tank. When load sensing control spool (10) is disabled, an increase in the power shift