The grab of wharf crane is not closed tightly.

This cylinder is short of oil. It is caused by the inclination and seizure of the middle bearing beam.

1. If the cylinder is not tightly closed due to lack of oil, replenish oil in the oil tank, move the bearing beam up and down repeatedly, and exhaust the air in the cylinder rod cavity.

2. The bearing beam is tilted and stuck, and the falling is not in place, which is caused by the deformation of the upper part of the piston rod of the oil cylinder. Check whether the joint between the bearing beam and the oil cylinder is loose or deformed, and re-tighten the connecting nut. If there is any deformation, correct the structural parts or replace the corresponding parts.