FILTER (SEM) 5677789 - Caterpillar

Nine pistons are assembled into barrel (1). The end face of the barrel contacts valve plate (19). The valve plate has two oval ports (21) and (22). Ports A and B are connected through hydraulic hoses to the swing control valve. When the swing control is activated, the control valve allows oil to flow to the swing motor. Refer to the Systems Operation, "Swing Hydraulic System" for more information on the swing control valve.Swashplate (20) is located opposite of valve plate (19). Pressure oil flows from the main hydraulic pump through the swing control valve to port A of the valve plate. The oil flows through the valve plate and the oil enters the cylinder that is aligned with port A. The oil pushes the piston, and the pushing force is converted into rotary motion by the swashplate. Because the barrel is splined to the drive shaft, the rotary motion is transferred to the drive shaft. The drive shaft then turns the upper structure through a set of planetary gears.The oil flows out of the swing motor through port B. For the reverse rotation, the oil enters through port B and the oil exits through port A.The two relief valves protect the swing motor against pressure spikes.Swing Parking Brake
The swing parking brake is a disc brake. The parking brake is engaged with spring force, and the parking brake is released with pilot pressure. The swing parking brake is released when any of the hydraulic controls are moved except the travel.
Illustration 5 g02298859
Parking brake (parking brake engaged)
(1) Barrel
(9) Spring
(10) Brake piston
(11) Disc plate When all of the hydraulic controls are in the NEUTRAL position, the spring forces the brake piston to engage. Oil is pushed out of the brake chamber through the drain port. This action prevents the swing motor from turning the machine.Disc plate (11) is splined to barrel (1). When the pilot oil that flows to the parking brake is shut off, the spring force pushes the brake piston (10) against the case. The barrel and the housing are held against each other by the force of friction, and the drive shaft is locked.
Illustration 6 g02298860
Parking brake (parking brake disengaged)
(1) Barrel
(9) Spring
(10) Brake piston
(11) Disc plate When any of the hydraulic controls are activated except travel, pilot oil enters the pilot port. Pilot pressure is supplied to the brake piston (10). This pressure causes the brake piston to shift against spring (9). The barrel and the case are not held together by the force of the friction. This action causes the brake to release and the drive shaft can rotate freely.Relief Valve
Illustration 7 g02298861
First stage relief
(6) Relief valve
(16) Passage
(17) Passage
(23) Spring
(24) Piston
(25) Sleeve
(26) Valve
(27) Chamber
(28) Passage
(29) Passage
(30) Passage Relief valves (6) and (15) are located in the top of swing motor (13). The swing relief valve has a two-stage relief action. The first stage provides a cushion effect at a start or stop of the swing operation. The second stage limits the pressure in the swing circuit to the relief