What Is a Chain Hoist?
A chain hoist is a piece of lifting equipment that can be used to maneuver heavy loads. These are commonly found on construction sites, manufacturing plants, warehouses and automotive repair shops.
Unlike lever hoists which require the operator to be right next to the load, a chain hoist can be operated from a distance using mechanical advantage.
Multiplication of Force
A chain hoist has multiple pulleys held together by a closed chain, allowing it to multiply the force applied by users when lifting heavy objects. When the chain is pulled, a series of gears and sprockets inside the device convert the energy into mechanical motion. This multiplication of force enables users to lift loads much larger than they could on their own.
A small, central gear in the device rotates a primary sprocket that powers the load chain. The chain rests on this sprocket, allowing it to lift and lower the load with minimal friction. A large, secondary sprocket also resides in the chain hoist’s device. The secondary sprocket has smaller teeth that can be engaged with the smaller, central gear, causing it to move the chain further for each rotation of the driver shaft.
When using a chain hoist, the operator should be a safe distance from the load and never touch it directly. A grab hook is placed on the top of the device, which can be used to chain hoist attach slings, lifting chains, or load itself. The device also has a hand chain that sits on a wheel located in the lifting mechanism and needs to be pulled manually in order to operate.
Most electric chain hoists incorporate an electronic motor control mechanism that monitors speed, voltage, current, and temperature to ensure that it’s operating properly. These devices also utilize a fail-safe mechanism that prevents damage from overloading or overheating. This system also enables users to control the device remotely via a pendant or radio remote, which improves efficiency and reduces the chance of injury for workers.
Redistribution of Force
The force applied to the chain hoist is multiplied through a system of gears and sprockets inside the device. This redistribution of force decreases the amount of energy it takes to lift a load and helps you conserve your own strength. It also increases the speed at which you can lift and lower a load.
A chain hoist works by using a system of pulleys that are connected to each other in the form of a closed chain. These pulleys are positioned throughout the hoist body and can be moved to adjust the height of the load. They can also be rotated to change the direction in which the load is lifted. The chain is then attached to a hook or lifting attachment on the end of the hoist. Some chain hoists have friction brakes that help stabilize the load during descent.
Other variations on the basic design of a chain hoist include lever devices that use a single side lever that’s directly attached to the lifting mechanism. They can be operated by hand, making them ideal for high vertical lifts in situations where you may not be able to stand directly next to the hoist.
Lever chain hoists can handle a wide range of loads and are available in varying capacities from 14-ton to 9-ton. Some models feature swiveling hooks that make it easy to attach the lever to the bottom chain hoist of the load and connect it to the chain located through the device’s driver shaft.
Safety
A chain hoist is a dangerous piece of equipment, even in the hands of an experienced operator. Safety precautions must be taken at all times to avoid accidents and damage, both to the hoist itself and to the load it is lifting.
A corroded chain or one that has become physically damaged can lose its tensile strength and cause the load to drop, potentially injuring people or damaging property. Wrong chain selection or interchanging chains can also lead to jamming or overload. A twisted or loose chain can crush feet, and sharp metal shavings in the chain can cut fingers and hands.
Operators must be qualified, with good hand/eye coordination and spatial orientation, and have a good depth perception to operate the hoist correctly. Detailed training and routine maintenance procedures should be part of any workplace’s health and safety regime.
Digital automation can improve safety significantly by preventing the hoist and load from approaching too closely to walls, internal structures or buildings, walkway routes that pedestrians may be using, or other objects. Columbus McKinnon’s Magnetek LaserGuard Mini collision avoidance system, for example, can programme a no-fly zone into the control systems of a hoist that will prevent it and its load from moving too close to these obstacles. The system is simple to program and provides an initial slowdown point, followed by a stop point if the hoist is on a collision course with another object.
Maintenance
If a chain hoist is to be used for an application that requires heavy lifting, it is essential that it be maintained in good working order. This maintenance should include regular examinations of the equipment and checking for wear, deterioration or breakdowns. It is also important to test the safety features of the hoist to ensure they are functioning properly and can protect the operator and others.
Hoist inspections should be carried out by qualified service personnel while the hoist is not supporting a load. The inspection should include a thorough examination of the load chain to identify signs of wear and tear, such as stretching, nicks or cracks. The chain should be replaced if any of these signs are present. The load chain should be lubricated with the manufacturer’s recommended lubricant on a regular basis.
It is also important to check the wire rope for distortion, kinking or unstranding, deposits of foreign material or dust, main strand displacement or core protrusion. If a wire rope is showing any of these signs, it should be removed from use until it has been repaired or replaced by a qualified service technician. It is also crucial to inspect the motor brake and ensure that the braking distance meets or exceeds the manufacturer’s specifications. In addition, the contactor contacts should be free of significant pitting and deterioration.