Description of the failure
The main and secondary hoists lower small opening jitter, and the shaking is more severe when lifting.
Failure analysis
The small opening of the hoisting lower shakes, and the lifting action is normal. The preliminary judgment is that the winch balance valve is not fully opened when the handle is small.
Troubleshooting
Step 1
Loosen the lock nut of the balance valve end cover screw and tighten the screw inside with an allens wrench to ensure that the x-port oil circuit can more easily push the balance valve spool. However, the failure is still the same during the test, and the pressure gauge is measured by the pressure gauge to measure the pressure of the whirlwind drop port by about 5mpa, and according to the design, this pressure can be completely opened to open the balance valve. Suspect whether the x-port damping is blocked, remove the damping of x-port 0.9, find that the damping is unobstructed, and then remove the damping of 0.7 in the contralateral plug, and no obstruction is found, as shown in the figure.
Step 2
The two damping positions are exchanged, tested again, the fault is still the same, judged as the balance valve internal valve sleeve and other non-active, apply for a new balance valve after the test, the small opening of the hoist drop is no longer shaking, but the main whirlwind 4 times the rate of hanging about 8 tons, the small opening of the whirlwind is still shaking. So the end cap damping was reversed again (x-port damping was 0.7, contralateral plug internal damping was 0.9);
Step 3
Testing again, the hoist descent action is normal, whether it is an empty hook or a lifting weight, the small opening movement of the hoist descent is smooth.
suggestion
The x-port damping of the balance valve should be installed with 0.7 to ensure that the balance valve can also open the balance valve stably when the handle is small to ensure the stability of the hoist during the descent.