The slewing device is composed of a brake valve, a slewing motor and a slewing reduction box. Through the slewing device and the slewing bearing, the upper turntable of the excavator can rotate in all directions relative to the lower car body.
Rotary motor
The turn motor is a swash plate type axial piston motor, and its structure is shown in Figure 5-6. The main parts of the motor include a fixed swash plate 5, a cylinder block 9, a plunger 8, a valve plate 3, a motor housing 6 and a parking brake. The parking brake is a wet multi-disc brake, which is composed of a center plate 1 and a friction plate 2. The snorkel 4 is embedded in each plunger 8, and there are 9 plungers with sliding shoes in the cylinder 9. The cylinder 9 is mounted on the shaft 7 through splines.
The rotation speed of the slewing motor changes depending on the amount of oil delivered from the pump. The oil from the oil pump flows in from the motor inlet (A), causing the plunger to move from the bottom dead center to the top dead center. Then, the sliding shoe 4 slides along the fixed swash plate 5 to make the plunger 8 move linearly back and forth in the cylinder 9.
When the high-pressure oil enters the motor from the oil inlet, the rotating torque of the output shaft of the slewing motor is transmitted to the slewing reduction box through the shaft 7, which drives the upper turntable to rotate. The return oil flows out from the motor outlet and then returns to the hydraulic oil tank. When the high pressure oil enters the same rotation motor in the opposite direction to the above situation, the motor rotates in the opposite direction, and the upper turntable also rotates in the opposite direction.
