Main Boom and Telescopic Mechanism of Truck Crane

The boom and telescopic mechanism is consist of a main boom, telescopic cylinder and retractable steel wire ropes.

Boom and telescopic mechanism

Retractable steel wire ropes of the main boom
A) Operate the telescopic mechanism, the boom extends 2-3 meters
B) Tighten the retracting wire ropes on both sides with adjusting bolts.

The retracting wire rope must not be turned when the bolt is tightened.

Operation of main telescopic boom
The telescopic mechanism level sets in the control room:
Operation manual as below

Push the level forward boom stretch
Pull the level backward boom retract

Stop: Move the level to the neutral position, the boom stops stretching. There has balance valve in the hydraulic system, it not only makes the stable expansion and contraction, but also make sure the boom stay in any position.


1) Before boom stretches and retraction, check whether the head of the telescopic boom (ie the pressure plate) and the head of the following arm are pressed tightly. If it is not pressed, it should be adjusted to pull it tightly.

2) When the boom telescopic, the hook will move up and down. You need operate the lifting level to adjust the height of the hook when operate the boom. So as to prevent the hook from rising too high to hit the head of the boom or too low to cause danger.

3) After the boom has been extended, after a certain period of time, the boom will retract slightly due to changes in the hydraulic oil temperature and boom telescopic state, main boom elevation angle, and lubrication status. Therefore, you should pay attention to the following matters and take effective measures:

Avoid excessive rise of hydraulic oil temperature;

When the boom is naturally retracted, telescopic operation should be performed to restore the required length.

4)The telescopic boom should be carried out at a low speed and steadily. It is not allowed to do the telescopic loaded. The telescopic boom can only be operated without an external load.