(1) Anatomy and schematic diagram of the final drive
(2) Composition of Doosan excavator final drive
The final drive consists of hydraulic motor, speed box, brake valve, parking brake, etc.
1) The role of the hydraulic motor The hydraulic motor is a swash plate type axial plunger motor, which converts the hydraulic pressure of the hydraulic oil from the main pump into the rotary torque of the rotary motion
2) The role of the brake valve (brake read includes safety suction valve, balance valve) When the main valve spool returns to the neutral position, the walking motor continues to rotate due to the inertia of the vehicle body, and the motor acts as a pump to make the return High-pressure back pressure on the oil side forces the motor to stop and brake.
3) The role of parking brake The parking brake is a friction disc brake mechanism, which is integrated with the hydraulic motor.
When the excavator is parked on the inclined ground, avoid the phenomenon of rolling and slipping.
(3) Three working processes of final drive
Working process 1
1) Release the brake:
Operating walking joystick
The hydraulic oil from the control valve enters the balance valve (19) through the small hole in the balance valve (19). The balance valve (19) moves upward. The pressure oil enters the cavity A of the brake piston (12) in the direction of the arrow. The spring (11) The force of the friction plate is eliminated and the brake is released
(4) Speed conversion of travel motor
When the flow rate of the pump is unchanged, the speed of the motor rotation can be changed by changing the angle of the motor swash plate (4) ① When the travel low speed (L) is selected, the travel speed solenoid valve is not energized. The pilot oil from the pilot pump cannot flow to the throttle Check the end face of (9). The swash plate (4) angle of the walking motor is at the maximum position. The walking motor has a large capacity and a low speed. When the walking speed is selected, the walking speed is electromagnetically energized, the swash plate angle becomes smaller, the walking motor capacity becomes smaller, and the speed becomes faster.
