TRUNNION 1635778 - Caterpillar

Pressure Sensors
Pressure sensor (21) is connected to pilot oil for boom down control. Pressure sensor (25) is connected to pilot oil for a swing RIGHT operation and swing LEFT operation. These two pressure sensors send an electrical signal to the machine ECM.When a boom DOWN function is performed, pressure sensor (21) sends an electrical signal to the machine ECM. The machine ECM then sends a signal to the following components:
PRV for boom regeneration valve (32) limits pilot oil to the boom regeneration valve.
The AEC system is activated in order to lower the engine rpm.
Swing brake solenoid valve (61) is activated in order to release the swing parking brake.
Negative flow control valve (29) regulates the pressure that will be supplied to the pump regulators. The negative flow control pressure forces the swashplate in the pump to the correct angle to limit the flow and pressure from the main pumps.When a swing operation is performed, pressure sensor (25) sends an electrical signal to the machine ECM. The machine ECM then sends a signal to the following components:
The solenoid valve for swing priority (40)
Swing brake solenoid valve (61) is activated in order to release the swing parking brake.
Negative flow control valve (29) regulates the pressure that will be supplied to the pump regulators. The negative flow control pressure forces the swashplate in the pump to the correct angle to limit the flow and pressure from the main pumps.Drive pump pressure sensor (48) and idler pump pressure sensor (49) are located on main control valve (7).Straight Travel Valve Circuit
When a swing operation and/or implement operation is performed during a travel operation, the increase of pilot pressure in pilot line (23) and/or pilot line (26) activates implement pressure switch (24) and/or swing pressure sensor (25). The implement pressure switch and/or the swing pressure sensor sends an electrical signal to the machine ECM. The machine ECM activates the solenoid valve for straight travel (47). Straight travel control valve (46) shifts. The straight travel control valve maintains straight travel even though there is a swing operation or an implement operation during travel. For more information concerning the operation of the straight travel control valve, refer to Systems Operation, "Control Valve (Straight Travel)".Swing Parking Brake
When the hydraulic activation control lever is placed in the UNLOCKED position, pilot oil in passage (62) flows through valve (56) and passage (55) in order to provide oil to the swing brake solenoid valve (61). When any of the joysticks are moved from the NEUTRAL position, the increase of pilot pressure activates one of the following pressure sensors or pressure switches: implement pressure switch (24), pressure sensor (21) for boom down control and pressure sensor (25) for swing control. The pressure switch and/or the pressure sensor sends an electrical signal to the machine ECM. An electrical signal from the machine ECM energizes the swing brake solenoid valve (61) once the pilot oil pressure exceeds 500 kPa (73 psi). Pilot oil in line (8) flows to swing brake (9). This oil releases