The type and structure characteristics of a crane, grab
Grab bucket is a form of to catch loading and unloading grain material or long products fetch device.
According to the jaw closed and open drive in a different way, grab bucket can be divided into rope type grab and grab power type two kinds big.Closed rope type grab on wire rope pulley block together to achieve the purpose of grab materials have closed, generally divided into the single line and double line three and four, with the corresponding types of hoisting mechanism.Dynamic type grab depend on external energy, through the motor drive pulley block device, hydraulic or pneumatic etc make the jaw opening and closing.
1. The rope grab
1) double disc grab
Rope grab long poles is the most common structure form in double disc double rope grab, it respectively by two independent wire rope with the opening and closing of the hoist drum and the hoist drum is linked together, by the operation of the hoisting mechanism of different combination, realize the opening of the grab bucket elevator.
If the crane hoisting mechanism adopts two sets of double drum, should use four rope grab.Because of rope branches increases, the diameter of the single wire rope is reduced, so grab the pulley block structure is more compact, and to improve the stability of the grab bucket work.
Opening and closing of the single rope grab and lifting steel wire rope with the same root, rely on the grab the open-close mechanism to complete the fetch and discharge.Single rope grab can with ordinary single drum lifting mechanism, its structure and complex operation, low productivity.Control method of the single rope grab crane institutions have tow cable, automatic bucket and the wireless remote control bucket and so on a variety of ways.
Timber grab: by using the theory of traditional grab grab, will fetch parts made of tooth shape, can isometric profile for wood material handling operations.Timber grab has a pair of symmetric alternating curved tooth, the shape of the curve of gear profile's ability to grab bucket, general requirements into a bundle of logs, timber grab both can grab and clamping single small diameter log.
More than 2) disc grab
More disc grab four disc, five and six disc and eight disc, of which six disc is most common.The jaw plate edge is sharp claws to grab for larger particles block of stone, cast iron pieces, etc., can also be fetching large bulk viscosity.
Disc grab bucket and a single rope, double rope, and four rope type, usually the jaw plate hinge on the same beam, synchronous open and close, suitable for grasping degree difference material.
Asynchronous open-close disc grab more applicable to grab size and irregular shape, materials such as scrap metal, rocks, etc.It differs from traditional to grab more discs in the jaw plate hinge in a sliding shelves, in this way, jaw plate can be rotated around the center of grab, can move up and down along the sliding plane, again make grab lumps in sizes can asynchronously when opening and closing.
2. Power grab
1) electric grab
Electric grab on installing an electric hoist beam control opening and closing rope or is driven by electric screw jaw, grab the opening and closing action.
2) hydraulic grab
Hydraulic grab next beam installed on a set of hydraulic system, through the hydraulic cylinder grab stretch and shrink to open and close.And grab the cable through the cable winding system is implemented on the crane.
Electric hydraulic disc grab more each jaw is a separate slider - link mechanism.Through various hydraulic cylinder drives the jaw opening or closing, asynchronous open-close can grab.Electric hydraulic system installed in the center column, also can be installed on the crane, through a hose connected to grab bucket hydraulic cylinder.Electric hydraulic disc grab grab capacity is big, more adapted to grab the irregular shape materials.
