In recent years, with the rapid development of urban economic construction, a large number of cranes controlled by the hydraulic system are used for municipal building and industrial production as the first line, playing an increasingly important role. So it is necessary to learn the composition, common faults and measures of truck cranes.
The truck crane which is mounted on a normal or a special vehicle chassis is one kind of Cranes, its driving cab and crane cab are provided separately. The truck has many advantages, such as mobility, transferring quickly, suitable for highway driving, high job performance, structure is relatively simple, cost-effective, less Job aids time, working height and amplitude can be converted at any time. The disadvantages are that when the boom truck is working, it needs to support legs, high flatness requirements on the ground, and can not work in the soft ground. But for modern urban construction, it can satisfy the vast majority of situations. Currently, the truck crane has a broad lifting capacity in the range of 8 tons to 1, 500 tons, such truck cranes are the largest output and are also the most widely used.
The crane can be mainly divided into two parts, the upper part and the lower part. Those are supporting base portion and operation portion. The supporting base not only includes chassis which can travel on the road and frame legs and other load-bearing structures, but also chassis can provide power to the upper part by the Center rotors; the upper part includes rotating bodies consists of rotary support that can achieve 360-degree rotation, rotary gear and rotary hydraulic truck system; The amplitude of the change mechanism consists of varying amplitude cylinder and hydraulic truck system components; hoisting mechanism consists of the winch gear, hoisting rope, lifting system;a Power telescoping main jib, deputy jib, turntable, counterweight, working chamber, electric control and lighting systems etc.
For a crane, the most common faults generally occurs in the hydraulic system, so it is necessary to understand some of the common faults of hydraulic systems, maintain measures and maintenance methods.
Hydraulic system
The hydraulic system is the key core for crane, all suspension load actions are driven by the truck system to complete. The hydraulic system that determines the performance of the hydraulic crane is an important criterion for testing the quality of crane.
According to assembly distribution of truck system on the crane truck, it can be divided the upper hydraulic systems and the lower systems.
The upper system:
Amplitude loop: control stretching of varying amplitude cylinder to realize the ups and downs
Retractable Loop: control stretching of telescopic boom to realize all the sections to stretch and retract.
Rotation circuit: control the rotation of the swing motor to realize the whole point of around rotation.
Lifting circuit: including main lifting and deputy lifting. Control the rotation of rotary motor to achieve the rise and fall of the main hook and auxiliary hook when are hanging loads.
The lower system:
Power system: pump absorbs oil from the tank to achieve the high-pressure oil to provide power for the entire system. It is the heart of the system.
Support leg loop: control the telescoping of nine supporting leg cylinder (four horizontal and five vertical supporting legs), to ensure stability when the cranes are on operations.