Essential Guide to Overhead Cranes: Identifying Types and Safe Operation Principles

Using a crane in an industrial setting can be dangerous. However, following some simple general safety requirements keeps everyone safe. As previously discussed, the crane should never be loaded beyond its rated load. This information should be plainly marked and visible from the ground on each side of the crane and all hoisting equipment. Cranes must have a minimum clearance of 3 inches overhead and 2 inches on each side to ensure there are no obstructions in the way. If walkways are present in the workplace, they shouldn't be placed where the use of the crane would interfere with worker safety. If the runways of two cranes run parallel to each other, there needs to be adequate clearance between the two bridges. If the crane has a cab for its operation, the layout should ensure that all controls are in a convenient location for the operator to reach and use. When facing the hook and load or the direction of travel, the operator should have a full view of the load hook and the cab should be properly lit for the operator to see clearly at all times. Operator cabs need to have a minimum of 3 inches of clearance from fixed structures anywhere in their paths. For cranes where footwalks are necessary for operation, there should be a minimum head clearance of 48 inches and they should be designed with an anti slip surface designed to withstand a distributed load of 50 pounds per square foot. Any ladders used to access cranes or footwalks must be permanently secured in place, and stairways should have metal handrails and be made of anti slip material. A trolley stop should be installed at each end of a crane travel trolley to limit the travel of the trolley and resist the force of the trolley as it comes to a stop. Trolleys should be equipped with bumpers or other automatic devices to ensure safe operation unless specific low risk conditions are met, such as slow movement, limited travel distance or operation away from the ends of the bridge or Runway. When bumpers are required, they must be capable of stopping an unloaded trolley moving at 1/3 of its rated speed with a deceleration not exceeding 4.7ft per second. If multiple trolleys operate on the same bridge, each must have bumpers on the ends that face each other. Additionally, bumpers must be constructed and installed in a way that prevents parts from detaching or falling if the bumper fails. Bridge trucks must have rail sweeps that extend below the top of the rail and in front of truck wheels. Guards should also be installed for hoisting ropes and other moving parts of the crane. Guards must be installed if hoisting ropes are close enough to other parts of the crane and that rubbing might occur, or if there's a chance that ropes could come in contact with bridge conductors. Other exposed moving parts like gears, screws, projecting keys and chains should also be protected by securely fastened guards. These guards should be capable of supporting the weight of a 200 pound person unless they are in a location where it would be impossible for a worker to step on them. Each hoisting unit of a crane must have at least one self setting holding brake applied to the motor shaft or gear train and to ensure the load doesn't move when the power is off. In most cases, an additional control braking system is also required to prevent the load from overspeeding during descent. Holding brakes must meet specific torque requirements based on the braking system used, 125% when used with a control braking mechanism that isn't mechanical, 100% when used with a mechanical control braking system, and 100% if two holding brakes are used. They must engage automatically when power is cut, have smooth wear surfaces and be adjustable for wear. Cranes handling hot metal must use at least two holding brakes if they rely on power control braking. Control braking systems such as regenerative, dynamic or mechanical methods must be able to maintain safe lowering speeds of rated loads. Foot operated brakes used for trolleys and bridges shouldn't require a force of more than £70 to activate. Foot brake pedals must be made to prevent the operator's foot from easily slipping off the pedal and should have automatic means for positive release when pressure is released from the pedal. Trolley and bridge brakes must be capable of stopping movement within a distance of 10% of the full load speed in feet per minute. A drag brake can also be used to prevent additional movement when the crane's power is off. On floor. Remote and pulpit operated crane bridge drives, a non coasting mechanical brake should be used. There are specific electrical requirements for crane equipment as well. Control circuit voltages must be under 600 volts for both AC and DC power, while pendant push buttons shouldn't exceed 150 volts AC and 300 volts DC. Suspended push button stations using multiple conductor cables must be properly supported to prevent strain on electrical conductors and pendant control boxes must be shockproof and clearly labeled. All electrical equipment should be enclosed to prevent accidental contact and must be protected from environmental factors like dirt, oil and moisture. With sturdy guards in place, cranes that don't have spring return controllers or momentary contact push buttons should be equipped with a device to disconnect all motors from the line in the event of a power failure. This device shouldn't allow the motors to be restarted until the controller handle is in the off position or a reset switch is engaged. Lever operated controllers should have a notch or latch that prevents handles in the off position from being accidentally moved to the on position. Controller operating handles should be easy to reach and move in the same direction as the movement of the load with the operator facing the direction of travel. For floor operated cranes, controllers should automatically lock into the off position when released. Resistors must be well ventilated, protected from combustible buildup and securely mounted to minimize vibration. Guards should also be in place to prevent molten metal or broken parts from falling on the operator. Switches must be accessible from the floor and lockable in the open position. Over travel limit. Switches must be installed for hoisting functions and lifting. Magnets need enclosed switches with a way to discharge the inductive load of the magnet. Runway conductors must be guarded or positioned to prevent accidental contact by operators. Extension lamps in cab operated cranes, if present, must use a grounded three prong receptacle not exceeding 300 volts because the work location can often be very noisy. Hand signals are commonly used to communicate with the crane operator. Hand signals should be agreed upon before operation of the crane begins and one person should be designated as the signal person. Common hand signals include ones to indicate hoisting, lowering, bridge travel, trolley travel, emergency stop and disconnected magnet. With so much that goes into crane operation, there are certain requirements to becoming a qualified crane operator. It.