SHAFT-CUTTER 8C1737 - Caterpillar

Pilot oil from the pilot control valves flows through pilot lines to the ports on the bottom of the main control valve to perform the opposite operation.The following example is given for the BOOM LOWER operation and the BOOM RAISE operation. Machine operations for a stick operation, bucket operation, travel operation, and swing operation are accomplished in the same manner as the boom operation.When the joystick for the boom is moved to the BOOM RAISE position, pilot oil from pilot control valve (24) flows through pilot line (17) to boom I control valve (18). The pilot pressure shifts the boom I control valve. The oil delivery from the drive pump flows to the head end of the boom cylinders to perform the BOOM RAISE operation.When the joystick for the boom is moved to the BOOM LOWER position, pilot oil from pilot control valve (24) flows through pilot line (33) to boom I control valve (18). The pilot pressure shifts the boom I control valve. The pilot oil also flows through pilot line (19) to open boom drift reduction valve (20). The return oil from the head end of the boom cylinders flows through the boom drift reduction valve and the boom I control valve to the hydraulic tank. The BOOM LOWER operation is now performed.Implement and Travel Pressure Sensors
Pressure sensor (23) and (25) are connected to travel pilot control valve (8). Pressure sensor (35) is connected to pilot control valve (22) and pilot control valve (24). When all the joysticks and/or travel levers/pedals are in the NEUTRAL position, the pilot oil pressure to the pressure sensor is low. Pressure sensors (23), (25), and (35) are OFF. The machine ECM recognizes the OFF condition of all the pressure sensors. The AEC system is activated to lower the engine rpm.If any of the joysticks and/or travel levers/pedals are moved from the NEUTRAL position, the increased pilot oil pressure is sensed by the pressure sensors. When pressure is detected by pressure sensor (23), (25), and/or (35), the machine ECM activates the AEC system to increase the engine rpm.If both travel levers/pedals and either one of the joysticks are moved from the NEUTRAL position simultaneously, pilot oil pressure will increase at pressure sensors (23), (25), and (35). The electrical signals are sent to the machine ECM. The machine ECM energizes straight travel solenoid (14). Pilot pressure now activates straight travel control valve (13).The straight travel control valve provides hydraulic oil flow to travel control valves (12) and (15) from the drive pump. The idler pump supplies all oil delivery to the remaining valves within the main control valve.If the machine is equipped with a straight travel pedal, there will be a separate pressure sensor that sends a signal to the machine ECM. A signal is sent to the machine ECM to energize straight travel solenoid (14) when the straight travel pedal is moved from the NEUTRAL position.For more information concerning the operation of the straight travel control valve, refer to Systems Operation,