Leaf Chains have various applications and are regulated by ANSI. They are used for forklift masts, for low-speed pulling and tension linkage, and as balancers between head and counterweight in certain machine tools. Leaf chains are sometimes also referred to as Balance Chains.
Leaf chains are steel chains with a simple link plate and pin construction. The chain number refers to the lacing of the links and the pitch. The chains have specific features such as high tensile strength per section area, which allows the design of smaller mechanisms. There are A- and B- type chains in this series and both the AL6 and BL6 Series have the same pitch as RS60. Finally, these chains cannot be driven with sprockets.
Comparably, in roller chains, all of the link plates maintain higher fatigue resistance due to the compressive stress of press fits, whereas in leaf chains, only two outer plates are press fit. The tensile strength of leaf chains is high and the maximum allowable tension is low. When handling leaf chains it is important to consult the manufacturer`s catalogue in order to ensure the safety factor is outlined and use safety guards at all times. It is a good idea to exercise extreme caution and utilize extra safety measures in applications where the consequences of chain failure are severe.
Utilizing more plates in the lacing leads to the higher tensile strength. Since this does not improve the maximum allowable tension directly, the number of plates used may be restricted. The chains require regular lubrication since the pins link directly on the plates, producing a very high bearing pressure. Using a SAE 30 or 40 machine oil is frequently advised for most applications. If the chain is cycled more than 1000 times in a day or if the chain speed is more than 30m per minute, it will wear extremely fast, even with constant lubrication. Therefore, in either of these situations the use of RS Roller Chains would be more suitable.
The AL-type of chains should only be used under particular conditions such as when wear is not a big issue, when there are no shock loads, the number of cycles does not exceed 100 a day. The BL-type would be better suited under other conditions.
The stress load in parts will become higher if a chain with a lower safety factor is selected. If the chain is also used among corrosive conditions, it can easily fatigue and break very fast. Performing regular maintenance is essential if operating under these types of conditions.
The type of end link of the chain, whether it is an inner link or outer link, determines the shape of the clevis. Clevis connectors or clevis pins are made by manufacturers but usually, the user supplies the clevis. An improperly made clevis can reduce the working life of the chain. The strands should be finished to length by the manufacturer. Refer to the ANSI standard or contact the manufacturer.
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