DRUM AS (SEM) 5677777 - Caterpillar

Hydraulic Schematic for the Swing System
Illustration 1 g02293196
(1) Signal line for the swing brake control valve
(2) Swing brake valve
(3) Swing motor
(4) Swing brake
(5) Pilot line (swing brake release)
(6) Return line for the swing motor
(7) Drain line for the swing motor
(8) Oil supply for swing
(9) Pilot line
(10) Main control valve
(11) Left joystick
(12) Orifice
(13) Pilot logic passage
(14) Pilot line
(15) Swing control valve
(16) Pilot pump
(17) Main pump
(18) Pilot and travel speed manifold
(19) Suction line The swing system is controlled by the left joystick in the standard pattern for the joystick and in the alternate pattern for the joystick. The hydraulic control console must be activated in order for the joysticks to function. When the left joystick is moved to the left, the cab will swing to the left. When the left joystick is moved to the right, the cab will swing to the right. When the joystick is released from either position, the joystick will return to the NEUTRAL position.Reference: Refer to the Operation and Maintenance Manual, "Joystick Controls" for more information on the operation of the joysticks.Swing Right
When swing joystick (11) is moved to the right, pilot oil is directed from pilot pump (16) through the pilot line (9) to swing control valve (15). When the swing control valve shifts down, pump oil is directed from main pump (17) through the swing control valve (15) to swing motor (3). The swing motor rotates the upper structure to the right.Swing Left
When swing joystick (11) is moved to the left, pilot oil is directed from pilot pump (16) through the pilot line (14) to swing control valve (15). When the swing control valve shifts up, pump oil is directed from main pump (17) through the swing control valve (15) to swing motor (3). The swing motor rotates the upper structure to the left.Refer to the Systems Operation, "Swing Motor" for more information on the swing motor. Refer to the Systems Operation, "Main Control Valve" for more information on the main control valve and the swing control valve.Swing Brake Operation
Pilot pump (16) supplies pilot oil to swing brake valve (2) whenever the engine is running. Pilot oil is also supplied to passage (13) in main control valve (10). Orifice (12) creates a pressure differential on the left and right sides of the orifice. Whenever any one of the control valves is shifted from the neutral position, the pilot oil in passage (13) is blocked. Pilot oil pressure increases on the right side of orifice (12). The increased pressure in passage (13) causes brake valve (2) to shift to the right. Pilot oil in line (5) now flows to swing brake (4) and releases the brake.When the control valves are in the NEUTRAL position, pilot oil in passage (13) flows to the hydraulic tank. The pressure differential across orifice (12) causes oil pressure on the right side of the orifice to remain low. Therefore, swing brake valve (2) does not shift and no pilot oil is supplied from line (5) to the swing brake.Note: The