SPRING-DISC 1109283 - Caterpillar

Front Pump Pressure Sensor and Rear Pump Pressure Sensor
The front pump pressure sensor and rear pump pressure sensors are inputs to the machine ECM. The front pump and rear pump pressure sensors are located on the main control valve. The front pump pressure sensor monitors the pressure of the front pump oil in the front half of the main control valve high-pressure passages. The rear pump pressure sensor monitors the rear pump oil pressure in the rear half of the main control valve high-pressure passages.The pressure sensors send a pulse width modulated (PWM) input to the machine ECM. This pressure information is used for pump control and travel speed.Pump Displacement Sensor
Illustration 5 g03235271
Illustration 6 g03235722Note: The values in Table 5are for bench testing only. Values may not represent parameters for machine systems specifications.
Table 5
Rotational Range 24.15° Angular Rotation
Output Signal 500 100 Hz
Output PWM 8% - 92%
Rating + 7V ~ +12V DC The pump displacement sensor is a hall effect type sensor and is used to measure the pump swashplate angle. The machine ECM uses the pump displacement sensor input to determine the output current that is sent to the pump control manifold PRV's. The negative flow control PRVs and the power shift pressure PRV then change the angle of the swashplate to meet the required hydraulic flow demands.For more information on the pump regulators, refer to Systems Operation, "Pump Control (Main Hydraulic)".Outputs
The ECM responds to decisions by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or the service technician.Proportional Reducing Solenoid Valve
Illustration 7 g02703776Note: The values in Table 6are for bench testing only. Values may not represent parameters for machine systems specifications.
Table 6
Current Range 0 mA ~ 700 mA
Coil Resistance 11.5 0.5Ω (T=20° C) Power Shift Pressure PRV
The machine ECM continually monitors all of the input signals. The input signals are processed by the machine ECM and an output signal is sent to power shift pressure PRV at the pump control manifold. The power shift pressure PRV assists in controlling the output flow of front pump and rear pump.For more information concerning the power shift pressure system, refer to Systems Operation, "Solenoid Valve (Proportional Reducing) - Power Shift System".Reverse Proportional Reducing Solenoid Valve
Illustration 8 g02304374
Valve cutaway, hydraulic schematic symbol, and electrical connector designation
Note: The values in Table 7are for bench testing only. Values may not represent parameters for machine systems specifications.
Table 7
Current Range 0 mA ~ 700 mA
Coil Resistance 11.5 0.5Ω (T=20° C) Negative Flow Control PRV for the Front Pump and Negative Flow Control PRV for the Rear Pump
Proportional reducing valves for negative flow control are used in order to control the amount of NFC signal to the pump regulators. The machine ECM receives various input signals in order to control the flow limitation from the main hydraulic pumps. When the NFC valves are energized by the machine ECM, pilot oil pressure is directed to the main hydraulic pump regulators from the pump control