In the aircraft industry, hoists and chain falls are quite routinely used to lift engines, wing parts, and other heavy items. These hoists are primarily used indoors in a maintenance hangar. The chain falls and hoists can be manually operated, or they may be powered by electric motors. They offer a wide range of lifting capacities which can be up to 12 tons.
A proper examination is essential before the use of any piece of lifting equipment. Each chain falls hoist should be given a thorough inspection to meet the standards required for safety and efficiency. For examining, testing, and recertifying air chain fall hoists, most companies typically follow the ASME guidelines, which ensure maximum efficiency and safety when lifting heavy loads.
Before testing a proper examination of the chain fall hoist is essential. To properly inspect the hoist, strip the chain from the hoist, and take out the motor. Look at the motor for wear and if none is found, then lubricate the motor and reinstall it inside the hoist. Next, inspect the brake disks for wear as well. If those also pass inspection, then the place the chain inside the hoist once again and now it is ready to be tested.
Each hoist, depending on the tonnage, can be given a dynamic or a static load test. ASME guidelines specify that at least a static test should be performed of chain falls to meet its minimum standards. A dynamic test is considered beyond its minimum required standards but is often performed to ensure safety in critical applications.
Dynamic and static are not very different from each other. For the static test, take a digital load link, hook it up to the hoist and test it to 125 percent of rated and stamped capacity. To perform the test pull it up to 125 percent of its rated capacity, and then wait for 10-20 seconds. If there is no failure of any of the components of the chain fall hoist, then it may be declared as satisfactory under load testing. This is currently the standard set by OSHA and ANSI.
A dynamic load test consists of performing an overload test at 125 percent of rated capacity and testing hoisting, lowering of the load, and hoist-brake hold functions. Now hook up the hoist to a computer that can show a graph of force versus time. Bring it up to 125 percent of the load, now manipulate the hoist up and down to see if there are any deficiencies. This test exceeds OSHA and ANSI standards so you can be sure that the chain fall hoist has been tested to 125 percent and is not going to fail as per its rating. This is the current and most efficient way to prove a hoist is ready and safe to use.
Chain hoists are useful because the load can be stopped and kept stationary at any point. They allow quite precise vertical placement as their rate of travel is slow. Make sure that the chain fall hoists are rigged so that the upper and lower hooks fall in a straight line. They can be used in vertical up-down directions only. If the chain fall is attached at an angle, its upper hook may get damaged. The gear housing may also get damaged if it is resting against an object while under load.
Always make sure that the hoist is hanging freely. Before using the hoist, inspect the chain for signs of wear and tear, nicks, twists, etc. Check the chain guide for damage. Hooks should be checked for signs of opening up. Check that the hooks move freely and have safety catches installed. If the hoist has been subjected to shock loads or was dropped anytime, it should be inspected thoroughly before being put back in service. Check the load brake by raising the load a couple of inches off the ground and watching for creep.
If the chain fall hoist fails a test then it should be replaced as per the manufacturer’s recommendations. Different manufacturers use different pitches for their load chain. Chains made by one manufacturer may not fit properly with the lift wheel of another brand and the chain hoist may not operate at all. The load chains are designed for lifting applications only and should be destroyed and not used anywhere else. Never weld a chain as will destroy the heat treatment of the chain entirely and it will lose its integrity.
Some chain hoists have overload protection. This is considered an extra feature of the chain fall hoist but it is not an ASME requirement. Chain hoists with 3-20 ton capacity will have an overload clutch as a standard item. However, chain hoists with lesser capacity say 1-2 tons will not have an overload clutch.
It is important to inspect these devices regularly to ensure they do not slip or drop. This applies to all types of hoists, be it a handheld manual chain hoist or an overhead automated trolley hoist. In addition to regular inspection and testing, many operations use chain fall hoists and lift systems in tandem along with a force gauge to ensure that an overload does not occur.
e2b calibration provides chain falls/hoist inspection and verification with ISO 17025 accredited force generation and measurement. We can also conduct on-site inspections of your safety equipment and provide you with a detailed inspection report giving their condition based on the manufacturer’s specifications while meeting ASME guidelines. We are ISO-17025: 2017 compliant and registered with ANAB. Please contact e2b calibration for more information.