1 Overview
The oil of the front and rear pumps flows into the main control valve through the central oil passage, the bypass oil passage and the confluent oil passage, and then the oil flows into each brake to make it run. The oil passage in the main control valve is equipped with a check valve and oil hole to control the oil flow of the main pump to match with each brake, and make the compound operation freely.
The main control valve is equipped with a linear travel spool. If any brake is operated while walking, the linear travel spool is pushed to the left by the pilot oil pressure. Therefore, the left and right walking oil supply channels are connected, and an equal amount of oil flows into the left and right walking motors to maintain straight travel.
2. Compound operation of swing and boom
When operating the slewing and boom of a modern excavator, the spool and boom spool in the main control valve are simultaneously moved to this functional position by the pilot oil pressure from the remote control valve.
The oil of the front pump flows into the rotary motor through the rotary spool and into the boom cylinder through the boom 2 spool. The oil from the rear pump flows into the boom cylinder through the boom 1 spool in the right control valve. In this way, the upper turntable is turned and the boom is operated.
3. Compound operation of swing and arm
When the rotary and small arm are operated, the rotary spool and the small arm spool in the main control valve are simultaneously moved to this functional position by the pilot oil pressure from the remote control valve.
The oil of the front pump flows into the rotary motor through the rotary spool, and flows into the small arm cylinder through the small arm 1 spool.
The oil of the rear pump flows into the arm cylinder through the arm 2 spool in the right control valve, the upper turntable rotates and the arm is operated.
4. Combined operation of swing and bucket
When operating the swing and bucket, the swing spool and bucket spool in the main control valve are simultaneously moved to this functional position by the pilot oil pressure from the remote control valve.
The oil of the front pump flows into the rotary motor through the rotary spool in the left control valve. The oil from the rear pump flows into the bucket cylinder through the bucket spool in the right control valve. In this way, the upper turntable rotates and the bucket is operated.
5. Compound operation of slewing, boom, arm and bucket
When operating the swing, boom, arm and bucket, each spool in the main control valve is simultaneously moved to the compound function position by the pilot oil pressure from the remote control valve.
The oil from the front pump flows into the rotary motor, boom cylinder, and arm cylinder through the rotary spool, boom 2 spool, arm 1 spool, parallel channel and junction channel in the left control valve. In the valve, the boom 1 spool, arm 2 spool, bucket spool, parallel channel and confluent channel flow into the boom cylinder, boom cylinder and bucket cylinder.In this way, the upper turntable rotates and the boom and arm And the bucket is operated.
6. Compound operation of slewing and walking
When turning and walking, the turning spool and walking spool in the main control valve are simultaneously moved to this function position by the pilot oil pressure from the remote control valve, and the linear walking spool is pushed to the left by the pilot oil pressure from the pilot pump Pump oil flows into the rotary motor through the rotary spool. The oil of the rear pump flows to the motor through the right travel spool of the right control valve and the left travel spool of the left control valve.
In this way, the upper turntable rotates and the machine travels straight.
7. Combined operation of boom and walking
When operating the boom and the travel, the boom spool and the travel spool in the main control valve are simultaneously moved to the position of this function by the pilot oil pressure from the remote control valve, and the linear travel spool is pushed toward the position by the hydraulic pressure from the pilot pump left.
If the boom is lifted, the oil from the front pump flows into the boom cylinder through the spool of boom 2 and boom 1 through the parallel and confluent channels. The oil of the rear pump travels through the straight travel spool, and then flows through the right travel spool of the right control valve and the left travel spool of the left control valve for motor travel. In this way, the boom is operated and the machine travels straight.
8, compound operation of forearm and walking
When operating the arm and walking, the arm spool and the travel spool in the main control valve are simultaneously moved to the position of this function by the pilot oil pressure from the remote control valve, and the linear travel spool is pushed by the oil pressure from the pilot pump left.
The oil from the front pump flows into the boom cylinder through the spool of the arm 1 and arm 2 through the parallel and confluent channels. The oil of the rear pump travels through the straight travel spool, and then flows through the right travel spool of the right control valve and the left travel spool of the left control valve to move the motor. In this way, the arm is operated and the machine travels straight.
9. Combined operation of bucket and walking
When operating the bucket and walking, the bucket spool and walking spool in the main control valve are moved to the position of this function by the pilot oil pressure from the remote control valve at the same time, the linear travel spool is pushed towards the position by the hydraulic pressure from the pilot pump left.
The oil of the front pump passes through the confluence channel and then flows into the bucket cylinder through the bucket spool. The oil of the rear pump travels through the straight travel spool, and then flows through the right travel spool of the right control valve and the left travel spool of the left control valve to move the motor. In this way, the bucket is operated and the machine travels straight.
