Pipelayers with caterpillar tractors of special pipelaying modification as a base are widely used to perform lifting operations during the construction of gas, oil and other pipelines.
Sometimes Liebherr order in Moscow is used for this purpose. The main equipment of pipelayers is A-shaped boom of box section, which is located on the side of the longitudinal base, for example, on the lower frame of pneumatic wheeled machines. It is supported by hydraulic cylinders or a chain hoist system. Stability is ensured by a tilting counterweight or counterweight on the opposite side, which flies out depending on the load torque and is adjusted by a hydraulic cylinder. Pipelayers designed for low lifting capacities have a conventional non-retractable counterweight. Pipelayers are characterized by the fact that they can travel with a load on the hook that corresponds to the potentially expected load moment.
The main purpose of pipelayers is: laying single pipes, pre-welded and insulated pipelines, stop valves and any other loads into the trench. This construction equipment is also widely used during loading and unloading operations during transportation of pipe bundles (sections) and single pipes by bundle carriers and pipe carriers. The next area of use of these machines is the consolidated assembly of pipe coils at pipe welding bases and in-line welding of sections before the pipeline is laid in the trench. Depending on their technical characteristics, pipelayers are used as cranes in installation works during the construction of compressor and pumping stations and other facilities. Pneumatic wheeled pipelayers are mainly used in urban construction. Domestic industry produces pipelayers with load capacity from 6.3 to 50 tons at the lowest load outreach of 1.5 meters, while the hook lifting height is from 4.5 to 7.5 meters.
To increase the cross-country ability, stability and traction capabilities of crawler pipelayers, the crawler tracks are widened and lengthened, and the drive system is equipped with travel reduction units. Balancer or spring suspension in the front section of the crawler is replaced by a rigid suspension. The counterweight moving mechanism, hydraulic system, boom and load winches are mounted on the upper frame attached to the tractor frame.
In order to increase the cross-country ability, stability and traction capabilities of crawler pipelayers, the crawler tracks are widened and lengthened, and the drive system is equipped with travel reducers. Balancer or spring suspension in the front section of the crawler is replaced by a rigid suspension. The counterweight moving mechanism, hydraulic system, boom and load winches are mounted on the upper frame attached to the tractor frame. The wheels of the pipelayer are also connected to the main tractor frame by means of a rigid suspension system. The tractor diesel engine drives all crane mechanisms by means of a hydraulic or mechanical transmission.
To lift loads and change the boom outreach, double-drum winches are used, which have independent drive of drums due to friction clutches or reversible hydraulic breakers, which connect the drums to the mechanical transmission as a whole. Each drum is equipped with a closed-loop brake, which is automatically released when the friction clutch or breaker is engaged.
