CARRIER- 1481179 - Caterpillar

Illustration 1 g00627149
Swing Hydraulic SystemThe swing system is independent of the implement system and the travel system. The 5230 excavator has three bent axis type motors and three swing drives. Two swing motors and two swing drives are located on the rear 90 degree segment of the swing gear. The third swing motor and swing drive are located at the front of the swing gear.The swing control valve directs pump flow from the swing piston pumps to all three swing motors at the same time. Each swing motor drives a swing drive. The swing drives are planetary reduction drives. A spring engaged swing parking brake is located inside each swing drive. The swing parking brakes are released with low pressure pilot oil that is controlled by the swing pressure switch, the machine control module, and the swing parking brake solenoid valve.The swing system uses an open center swing control valve. The swing control valve is load sensing. The swing control valve includes the directional control spool and a swing pressure relief valve. The swing dual pressure relief valve has a high pressure relief setting for acceleration and a lower pressure relief setting for deceleration.The swing control valve is mounted on the upper frame just to the left of the front control valve. The oil for the swing system is supplied by two swing piston pumps. The swing piston pumps are variable displacement piston pumps. The two swing piston pumps are splined together in order to form a tandem swing pump. The tandem swing pump is mounted on the right side of the pump drive.The swing control valve consists of the directional control spool, the load check valve, and relief valve. One line from the swing high pressure screens supplies hydraulic oil to the swing control valve. A supply line and a return line connect the swing control valve to the swing crossover relief valve. The swing crossover relief valve is mounted on the left rear swing motor. The swing crossover relief valve is a manifold. The swing dual pressure relief valve and the makeup check valves for the swing circuit are located in this manifold. Additional supply lines and return lines connect the swing crossover relief valve to the front swing motor and the right rear swing motor. The swing back pressure relief valve is mounted to the swing control valve. The swing back pressure relief valve is located in the swing return line. The swing back pressure relief valve maintains a back pressure in the swing hydraulic system.When the left implement control lever is activated for a swing function, low pressure pilot oil is sent to one end of the swing control valve in order to activate the swing function. Swing pilot oil