A Hyundai 335-7 hydraulic excavator, the machine works for 5400 hours. Recently, the phenomenon of slow turning speed has appeared recently. Except for slow rotation, all other operations of the machine are normal.
According to the principle of rotary hydraulic system of Hyundai R335-7 excavator, there are 3 possible reasons for failure.
One is the malfunction of the rotary motor.
Two is the hydraulic pump or variable servo valve failure;
The three is the failure of the rotary control valve, the boom priority solenoid valve or the rotary logic valve.
Yuncheng Hyundai R335-7 rotary speed slow failure investigation:
1. When doing the rotary motion, the pressure of the P pump A point is 32MPa and the pressure is high. When measuring the walking system, the speed of both sides of the walking system is equal, and the speed is equal to the standard.
2, check the brake piston working normally, the valve core of the rotary logic valve has no stagnation. It is inferred that the valve is in the throttle position and the B point pressure of the rotary valve is always 3.9MPa, which leads to the high pressure of the P2 pump and the slow speed of rotation.
3, but after examination, the valve works well and is not in throttling position.
4, continue to dismantle the boom priority solenoid valve, found that the valve spool stuck in the constant position, resulting in insufficient supply of rotary hydraulic system.
5, after cleaning the boom priority solenoid valve, install the test machine normally.
After the above 5 steps of troubleshooting, Yunfeng's modern excavator action returned to normal. The Hyundai R335-7 slew speed was slow and the trouble was eliminated.
