Powering Your Overhead Crane
So what powers your overhead crane? Overhead cranes typically are man-powered or electric, specifically:
Manual Powered Overhead Cranes Using Hand Chain
Hand chains consist of a series of interwoven formed welded or un-welded links according to the design specifications of the hand chain. The hand chain links fit pockets of the hoist hand chain wheel or sprocket. As you pull the hand chain, it turns the chain wheel and transmits power through the hoist gearing to the hoist load chain sprocket. Pulling the hand chain in one direction causes the hoist load hook to travel in one direction while pulling the hand chain in the opposite direction will cause the hoist load to travel in the opposite direction.
Hand chain manually operated hoists are available with only welded link load chain or roller load chain as the lifting medium. Higher capacity hand chain manually operated chain hoists may have multiple hand chains suspended from the hoist. Hoists that have multiple hand chains require multiple operators, each grasping and pulling one of the hand chains.
The hoisting motion of electric powered hoists is achieved by the operator grasping and activating a control device. The control device has push buttons or levers that energize, through a series of contractors and other electrical components, an electric motor. The electric motor transmits power through the hoist gearing to the hoist load chain sprocket or hoist drum; thereby, lifting or lowering the hoist load hook. Lifting is accomplished by actuating the lifting control and lowering is accomplished by actualling the lowering control. The controls could be marked: LIFT/LOWER; UP/DOWN; RAISE/LOWER; arrows designating up/down; or a combination of such markings. Hoist lifting and lowering controls are usually push buttons mounted in a pendant control enclosure suspended from the hoist; or levers or switches mounted in a remote radio-control transmitter. Pendant control enclosures, radio-control transmitters or other control means could also be permanently mounted on the building structure or cab of an overhead crane depending on the application.
The control device used to lift and lower hoist motion may also contain controls for other motions or functions. Such controls include: trolley travel, overhead crane travel, power on/off, emergency stop, motions associated with below-the-hook lifting devices and other special functions associated with a specific application. Examples of such control markings may include, but are not limited to: EAST/WEST; RIGHT/LEFT; OPEN/CLOSE; START/STOP; etc.