AMPS

Crane resistors are used in conjunction with DC crane control which supply power to the crane motors. The crane resistors are used to control the speed of the crane motors. By varying the speed of the motors one varies the speed of the crane. On most direct current overhead traveling cranes there are either three or four motions. There is always a hoist, bridge and trolley motion and sometimes an auxiliary hoist motion. Each motion has a separate master switch, a separate motor and a separate control. The controls have various steps of acceleration normally either four or five. Each step of acceleration uses its own banks of resistors. All the resistors for one motion are stored in their own individual racks. By moving the handle on a master switch the crane operator selects which contactor is to be used. By selecting which contactor is used the operator cuts in or cuts out resistors which controls the speed of the crane. Once the crane is moving the crane operator normally throws the handle all the way forward for maximum speed. The accelerators are timed so the crane will accelerate smoothly. It takes a little while for the contactors to move through all their steps of accelerations. There are number of companies who manufacture crane resistors. Casey has over a thousand banks of crane resistors in stock ready for immediately delivery. Casey has hundreds of banks of Square-D and Cutler Hammer crane resistors in stock which are usually the most popular brands but we also have a large quantity of Post Glover resistors. Most of our resistors are used but we have some resistors that are new. All resistors are sold for a fraction of new price.