PUMP & LINES GP-SUMP 8N7219 - Caterpillar

Illustration 1 g06244666
Engine overspeed schematic
Illustration 2 g06196303
(1) Front control valve (brake)
(2) Rear control valve (brake)Brake control valves (1) and (2) are in the hydraulic tank compartment.
Illustration 3 g06196727
Schematic of the control valve (brake)
(1) Front brake control valve
(2) Rear brake control valve
(3) Port to the front service brakes
(4) Front service brake oil pressure sensor
(5) Resolver valve for front brakes
(6) Port to the rear service brakes
(7) Rear service brake oil pressure sensor
(8) Resolver valve for rear brakes
(9) Relay spool
(10) Control solenoid valve for front brakes
(11) Relay spool
(12) Control solenoid valve for rear brakes
(13) Port for return oil to the hydraulic tank
(14) Port from the service brake control valve
(15) Port from the service brake control valve
(16) Port from the brake accumulator
Illustration 4 g06197231
Front brake control valve
(1) Front brake control valve
(3) Port to the front service brakes
(4) Service brake oil pressure sensor
(10) Control solenoid valve for the front brakes
(13) Port for return oil to the hydraulic tank
(14) Port from the service brake control valve
(16) Port from the brake accumulatorThe main components in the engine overspeed control are front brake control valve (1) and rear brake control valve (2).The hydraulic circuits for the front service brakes and for the rear service brakes are separate. Each service brake circuit contains two solenoid valves, two pressure sensors and two shuttle valves.Control solenoid valves (10) modulate the oil supply to the service brakes when the engine over speed control is activated.Brake control valves (1) and (2) also supply pressure oil from the brake accumulator charging valve to the service brake control valve.Oil from the brake accumulator charge valve flows to port (16), and to the brake accumulators. The brake accumulator charging valve maintains a constant pressure to the brake accumulators, while the engine is running.Pressure oil from the brake accumulators enters brake control valves (1) and (2), through port (16). Pressure oil is directed to control solenoid valves (10) and (12).When the throttle position is greater than 60 percent and the engine speed increases to 2250 rpm, the Machine ECM energizes control solenoids (10) and (12). The monitoring system will activate a category 2-S warning and the engine overspeed indicator will illuminate on the monitor display when the control solenoids (10) and (12) are energized. As the engine speed drops below 2200 rpm the Machine ECM de-energizes control solenoids (10) and (12). The engine over speed indicator on the monitor display will turn off and the monitoring system will de-activate the category 2-S warning.If the torque converter lockup clutch is enabled and the engine speed reaches 2300 rpm, the torque converter lockup clutch will disengage.When control solenoid valve (10) is energized, pressure oil from the brake accumulator flows through control solenoid valve (10) to resolver valve (5). Resolver valve (5) moves up and pressure oil flows to the right side of relay spool (9). Relay spool (9) moves to the left, pressure oil from the brake accumulator flows through relay spool (9) to the service brakes. The required level of braking for engine overspeed control will determine the amount that