1. Hydraulic system in the relief valve: can inhibit the abnormal high pressure in the circuit to prevent damage to the hydraulic pump and motor, and to prevent the overload state.
2. boom swing safety device: when the accident occurred, the boom swing cylinder circuit in the high-pressure hose or tubing burst or cut off, the hydraulic circuit in the balance valve to play a role in locking from the lower chamber of the work Oil, so that the boom does not fall, so as to ensure the safety of operations.
3. Suspension telescopic safety device: When the accident occurred, the boom telescopic cylinder circuit in the high-pressure hose or tubing burst or cut off, the hydraulic circuit in the balance valve to play, locked from the lower chamber of the working oil, So that the crane itself will be retracted to ensure the safety of the operation.
4. height limit device: hook up to the specified height, the touch limit hammer, open the trip switch, "over the" indicator light that is lit, while cutting off the hook lift, boom out, hanging Arm to the operation of the operation to ensure safety. At this time as long as the manipulation of the hook down, the arm retracted or the arm up (that is, to the safe side of the operation) and other handles, so that the limit hammer lifting constraints, the operation is back to normal. In special cases, such as the need for a small over-winding operation, you can press the release button on the instrument box, then the role of the limit will be lifted, but this time the operation must be very careful to prevent accidents.