Classification and components of cranes
A crane is a mechanical equipment that works intermittently and repeatedly to vertically lift and horizontally move heavy objects hung on hooks or other lifting devices within a certain spatial range.
(1) Cranes can be classified according to their structure, including gantry cranes, boom cranes, and rope cranes. Bridge cranes can be divided into subcategories such as bridge cranes, gantry cranes, and loading and unloading bridges. Boom cranes can be further divided into subcategories such as tower cranes, gantry cranes, mobile cranes, cantilever cranes, and mast cranes. We commonly see bridge cranes, tower cranes, and mobile cranes in our daily lives.
Various types of construction cranes are usually composed of four parts: working mechanism, metal structure, power device, and control system. The working mechanism of a crane includes four main parts: lifting mechanism, slewing mechanism, slewing mechanism, and walking mechanism. The lifting structure consists of a prime mover, a drum, a wire rope, a pulley system, and a hook. There are mechanical and hydraulic transmission methods for lifting. Crane slewing refers to changing the distance between the center of the hook and the axis of the crane's rotation center. The form of the variable amplitude mechanism depends on the type of boom of the mobile crane. For truss cranes with constant length, the slewing mechanism adopts a wire rope slewing mechanism. The slewing mechanism of the mobile crane with telescopic boom adopts a hydraulic cylinder slewing mechanism. The rotary mechanism consists of a rotary drive device and a rotary bearing. The slewing bearing device of mobile cranes usually adopts rolling bearing type. The walking mechanism of a mobile crane is the chassis of the crane, while a wheeled crane uses a universal or specialized automotive chassis, or a chassis specifically designed for the crane. A crawler crane uses a crawler chassis. The walking mechanism of tower and bridge cranes is generally a specially designed operating track
(2) The metal structure of a crane includes the boom, rotating platform, A-frame, chassis, and tower body of a tower crane. The metal structure bears the weight of the crane and various loads during operation. The strength, stiffness, and stability of metal structures are three important indicators.
(3) The power unit of a mobile crane is an internal combustion engine, while the power unit of tower and other types of cranes is an electric motor.
(4) The control system of the crane includes a control device and a safety device. The control system is equipped with clutches, brakes, and various control valves in the hydraulic transmission of the stopper.
