Adjustment of Hydraulic System of Truck Crane

Hydraulic system adjustment.

In the hydraulic system, the outrigger operating mechanism, boom extension, luffing, swivel, and hoist winch are all equipped with relief valves so that the system will not be overloaded to ensure safe operation. The relief valve pressure of the crane boom extension, luffing, and lifting winches is adjusted to 21 MPa.

The pressure of the relief valves has been adjusted at the factory and generally should not be arbitrarily changed. When replacing the relief valve or when it is really necessary to re-adjust it, the experienced engineer should adjust it according to the specified value after he is familiar with the construction of the system.

Adjustments follow the following method:

1)Adjust the retractor and luffing mechanism relief valve. Loosen the relief valve adjustment screw that controls the telescope and luffing mechanism, place the luffing mechanism control handle at the maximum amplitude of the luffing elevation angle, and gradually tighten the relief valve adjustment screw while looking at the expansion and contraction pressure gauge until the pressure rises. To 21MPA, lock the adjustment screw at random.

2)Adjust the lift valve relief valve. First, make a good leg, make the crane show the working state, loosen the relief valve adjustment screw to control the hoisting mechanism, shrink the boom to the rear of the crane, the amplitude is three meters, and the brake control port of the hoist and reducer Remove the tubing and plug the plug with the tubing.

Pull the handle of the hoisting mechanism and place it in the “Lift” position. Then gradually tighten the overflow valve adjusting screw and watch the lifting pressure gauge until the pressure rises to 21MPA. When you lock the adjusting screw at random. Install the control port of the winch and reducer brake.


1) After 250 hours of operation, the filter element of the oil filter should be inspected and cleaned or replaced if necessary.

2) The hydraulic oil tank will remove moisture or impurities once every two weeks from the bottom, and replace all hydraulic oil every other year (or work for 2000 hours). (If the oil is not deteriorated, it can be extended appropriately.)

Oil cycle) When the crane is used under a particularly harsh environment (eg smelters, chemical plants, etc.), the oil replacement cycle should be shortened accordingly.

3) Various valves of the hydraulic system have been commissioned before leaving the factory. The adjusted pressure and flow must not be touched.

4) It is not allowed to perform welding on the hydraulic cylinders without permission. It is forbidden to use the cylinders as welding ground conductors.

5) All kinds of mechanical parts, especially hydraulic system equipment, should not be attached to dirt, so after the operation, dust and oil must be removed.

6) The adjustment of the hydraulic system must be carried out in order according to the above requirements, and cannot be adjusted by other methods.