Types and construction of truck cranes
Type of truck crane
There are many types of truck cranes, and their classification methods are also different. The main ones are:
Classified by weight: light truck cranes (with a lifting capacity of less than 5 tons), medium-sized truck cranes (with a lifting capacity of 5-15 tons), heavy-duty truck cranes (with a lifting capacity of 5-50 tons), and super heavy-duty truck cranes (lifting weights) At 50 tons or more). In recent years, due to the use requirements, its lifting capacity has increased, such as the production of large-scale truck cranes of 50-100 tons.
According to the type of outrigger: frog type leg, x type leg, h type leg. The frog-type leg span is 0. It is only suitable for cranes with smaller tonnages; the x-type legs are prone to slippage and are rarely used; the h-type legs can achieve larger spans, and the stability of the whole machine is obvious. The superiority, so the hydraulic cranes currently produced in China mostly use h-shaped legs.
According to the transmission mode of the transmission: mechanical transmission, electric transmission, hydraulic transmission.
According to the lifting range of the lifting device (ie the turning range of the turntable): the full-slewing truck crane (the turntable can rotate 360° at will) and the non-full-turn truck crane (the turntable angle is less than 270°).
According to the structure of the boom: folding boom, telescopic boom and truss boom truck crane.
Basic structure of truck crane
Truck cranes are mainly composed of lifting, luffing, turning, lifting arms and car chassis. The development of hydraulic cranes, the electronics industry, the high-strength steel and the automotive industry has contributed to the development of automotive cranes. Mechanical transmission truck cranes, which are self-important and have long working hours, have been replaced by hydraulic truck cranes. The hydraulic system of the hydraulic truck crane uses a hydraulic pump, a quantitative or variable motor to realize the lifting and slewing of the crane, the variable amplitude, the expansion and contraction of the boom and the extension of the legs, and can be operated individually or in combination. The motor is protected against overheating and has safety features to prevent erroneous operation. Large-tonnage hydraulic truck cranes use multiple gear pumps, which can also accelerate the above-mentioned various actions when joining. In the hydraulic system, there are automatic overload safety valves, buffer valves and hydraulic locks to prevent accidents caused by overload or stall of the crane and sudden rupture of the tubing. The truck crane is equipped with an amplitude indicator and a height limiter to prevent overload or overhang, and the reel and pulley are provided with a device for preventing the rope from jumping.
For cranes below 16t, cranes are required, and cranes with 16t and above are equipped with torque limiters and alarm devices. The boom of a hydraulic truck crane consists of a multi-section arm section that can be designed according to the different requirements for lifting height. One type of expansion and contraction of the boom is sequential expansion and contraction, and the other is synchronous expansion and contraction. Most large-tonnage cranes use synchronous expansion to increase the lifting capacity. The expansion and contraction of each arm section is controlled by oil pressure and can be flexibly stretched. A crane with a jib is generally placed laterally or below the main arm when in a running state. The turntable is mainly used to arrange the lower fulcrum and the operating device of the hoisting mechanism, the slewing mechanism, the jib and the luffing cylinder. For medium and large tonnage cranes, some also place engines on the turntable. A slewing bearing that can withstand vertical loads, horizontal loads and overturning moments is used between the turntable and the undercarriage. In order to prevent the turntable from slipping during driving, a turntable locking device is provided. The slewing mechanism is driven by a metering motor. The output gear of the slewing mechanism meshes with the slewing bearing gear. The crane turret is turned 360° along the center of rotation. The amplitude of the boom is controlled by oil control from a single or double hydraulic cylinder. The crane is driven by a fluid control variable or a fixed motor through a reducer. Due to the use of the hydraulic torque converter, the movement of the various mechanisms of the crane can be steplessly shifted, so that the load can be reduced by the power control at the fretting speed. In order to prevent over-winding, a three-wire protection device and an alarm device are provided. Medium and large tonnage truck cranes can be equipped with sub-lifting mechanisms according to market needs for double hook operation.
Steel Structure,Structural Steel,I Beam Fabrication,Mild Steel Box Section
Guangdong Tianchen Steel Structure Engineering Co. Ltd. , https://www.tcsteeltech.com