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Monday, 6 April 2015

Classification of Chains

Classification of Chains Points : Classification of Chains, Hoisting and hauling (or crane) chains, Conveyor (or tractive) chains, Power transmitting (or driving) chains Chains, on basis of their use, are classify into the following group:
1. Hoisting and hauling (or crane) chains
2. Conveyor (or tractive) chains
3. Power transmitting (or driving) chains
1. Hoisting and Hauling Chains This chain is use for hoisting and hauling function and work at a utmost velocity of 0.25 m / s. Types of Hoisting and hauling chains are given below:
i. Chain with oval links
ii. Chain with square links
i. Chain with oval links Links of this type of chain are of oval form. Joint of every link is weld. Sprockets which are use for this type of chain contain receptacle to obtain links. Such type of chains is use just at low speeds for example in chain hoists and in attach for marine works. ii. Chain with square links Links of this chain are of square shape. Such type of chains is use in cranes, hoists, dredges. The industrialized cost of this type of chain is below that of chain with oval links, but in these chains, the kinking occurs simply on overcapacity.
2. Conveyor Chains These chains are use for moving and transmission the materials constantly at a speed upto 2 m / s. Type of Conveyor chains are given below:
1. Detachable or hook joint type chain.
2. Closed joint type chain.

Conveyor chains are generally prepared of malleable cast iron. These chains do not have smooth operation qualities. Conveyor chains run at slow speeds of on 0.8 to 3 m/s.
3. Power Transmitting Chains This chain is use for transmission of power, as distance among the centres of shafts is small. This chain contains provision for capable lubrication. Power transmitting chains are of the following three types.
i. Block or bush chain
ii. Bush roller chain
iii. Silent chain
i. Block or bush chain This type of chain was use in before time stages of development in power transmission. It generates noise as approaching or leaving teeth of sprocket as of rubbing among the teeth and the links. Such type of chains are use to a few extent as conveyor chain at small speed. ii. Bush roller chain This type of chain consists of external plates or pin connection plates, inner plates or roller link plates, pins, bushes and rollers. Pin pass through bush which is protected in holes of roller among the two sides of chain. Rollers are free to turn on bush which protect sprocket wheel teeth against wear. Pins, bushes and rollers are prepared of alloy steel.

This chain is very strong and simple in assembly. It gives good quality service under severe conditions. There is a little noise by this chain which is due to impact of rollers on sprocket wheel teeth. This chain can be use where there is a small lubrication.

Roller chains are regular and manufactured on basis of pitch. These chains are presented in single-row or multi-row roller chains for example simple, duplex or triplex strands.
iii. Silent chain This type of chain is also known as inverted tooth chain, it is planned to reduce the evil effects cause through stretching and to create noiseless operation. When the chain stretch and pitch of chain increase, links ride on teeth of sprocket wheel at a slightly enlarged radius. This mechanically corrects small change in pitch. There is no comparative sliding among the teeth of inverted tooth chain and sprocket wheel teeth. While correctly lubricated, this chain gives tough service and runs extremely smoothly and silently.

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