Operation of lifting and moving devices

Operation of the devices addressed in this course for moving objects and personnel follow.

1. Lifting devices, operation. Following is a discussion of the operation of cranes and other common lifting devices typically encountered in facilities.
   1. Bridge cranes travel on rails supported by columns. End stops are provided on the rails to limit crane travel. The crane columns may be separate or integral with the building steel. Foundations must be designed for the additional load of the crane. The crane consists of the bridge which spans the distance between the rails, a trolley which traverses the bridge and one or more hoists located on the trolley. End stops are provided on the bridge to limit travel of the trolley and limit switches are provided on the hoist to limit travel of a wire rope-mounted hook. Travel is normally controlled by a pendant with separate buttons for movement in the north, south, east, and west directions for the bridge and trolley and up and down for the hook on the hoist. Motor speeds can be in steps or variably adjustable. Automatic brakes are provided on all traversing and lifting motors. In some cases, the pendant is replaced with a radio controller, thereby eliminating the wire to the pendant. On larger cranes, controls can be provided in a bridge mounted operator cab. The lifting capacity of the crane must be clearly indicated and visible to the operator. Operators and personnel must not be under the lifted load at any time.
   2. A jib crane includes a counter weight foundation mounted column with a swinging jib. Stops are provided on the column to limit the swing of the jib and also on the jib to limit trolley movement. The hoist is pendant controlled and with limit switches to safely limit hook travel. The trolley and jib can also be powered if desired. The lifting capacity of the crane must be clearly indicated and visible to the operator. Operators and personnel must not be under the lifted load at any time.
   3. Gantry cranes consist of an inverted “U” shaped structure called a gantry. The structure is mobile and can straddle objects. A trolley traverses the upper cross member and supports a hoist. The gantry and trolley can be powered similar to a bridge crane. Stops and limit switches are provided as needed to limit movement of the gantry, trolley, and hoist hook. A pendant is used for control. The lifting capacity of the crane must be clearly indicated and visible to the operator. Operators and personnel must not be under the lifted load at any time.
   4. Non-powered lifting devices and rigging include hydraulic jacks, chain hoists, chains, wire ropes, slings, chokers, hooks, shackles and spreader bars. The lifting capacity of lifting devices and rigging must be clearly labeled. Operators and personnel must not be under any lifted load at any time and must not ride on any hook or load.
2. Elevators, operation. Elevators are used to lift freight and personnel. Lifting is accomplished by a hydraulic ram or cable drive with interlocks to control the acceleration, speed, stop positions, elevator doors, access doors and safety of the car. The elevator car/enclosure travels vertically in an elevator shaft with guide rails, and is provided with doors or a gate, roof hatch and push button controls. The doors/gate must be closed for the car to move. A mechanical safety brake is provided as a redundant safety to limit the travel of the car should all other mechanical and electrical interlocks and safeties experience a problem simultaneously. The lifting capacity of the elevator must be clearly indicated and visible to an operator. The car should be well lit, and be provided with an alarm, emergency lights and an emergency phone or intercom. Elevator entranceways should be clear of tripping and slipping hazards. Elevators are the only lifting and moving devices which may be used to lift personnel.