A crane is a multi-action lifting machine that vertically lifts and carries heavy loads horizontally within a certain range. It is also called overhead crane, aerial crane, crane.
The lifting machinery used in bridge construction can be generally divided according to its structure and performance. There are four major categories of light and small lifting equipment, bridge-type lifting machinery and jib-type cranes and cable cranes. Light and small lifting equipment such as: jacks, pneumatic hoists, electric hoists, balance hoists (also known as balance hoists), winches, etc. Bridge type lifting machinery such as beam cranes. Boom type cranes such as fixed swing cranes, tower cranes, truck cranes, tire cranes, crawler cranes, etc. Cable cranes such as elevators.
According to the nature of lifting: mobile crane, tower crane, mast crane.
Divided by driving mode: one type is centralized driving, that is, a motor drives a long drive shaft to drive the driving wheels on both sides; the other type is driving separately, that is, the driving wheels on both sides are driven by one motor. Medium and small bridge cranes often use a “three-in-one” drive method in which brakes, reducers and motors are combined into one. For ordinary bridge cranes with large lifting weights, for easy installation and adjustment, the drive device often uses universal joints .
According to the structure, cranes are mainly divided into light and small lifting equipment, bridge type (bridge type, gantry crane), boom type (self-propelled, tower type, portal type, railway type, floating boat type, mast crane), Funicular.
The main characteristics of a tire crane are: its driving cab and lifting control room are combined into one, and it is evolved from a crawler crane (crawler crane). The crawler and walking bracket of the walking mechanism are turned into a chassis with tires. The disadvantage of the crawler crane (crawler crane) track pads causing damage to the road surface is a material handling machine.
Overhead cranes are lifting equipment for lifting materials horizontally over workshops, warehouses and storage yards. As its ends sit on tall concrete pillars or metal supports, it looks like a bridge. The bridge frame of the bridge crane runs longitudinally along the tracks laid on the elevated sides on both sides, which can make full use of the space under the bridge frame to lift materials without being hindered by ground equipment. It is the most widely used and largest number of lifting appliances.
Some of the working characteristics of lifting equipment are intermittent movements, that is, the corresponding mechanisms of material taking, moving, unloading and other actions in a working cycle alternate. The development and use of cranes in the market are becoming more and more widespread. Due to the use of outriggers and cranes, there are often some accidents, and the speed is faster than crawler cranes (crawler cranes); the operation is stable, the lifting capacity is large, and it can be hoisted in a specific range, but the road must be smooth 、 The tire pressure meets the requirements, and the lift must not exceed 50CM from the ground; it is forbidden to walk with a load for a long distance.