Classification of Chain in Mechanical Engineering

Classification of Chain:

The chains on the basis of their use, are classified into the following three groups:

1. Hoisting and Hauling Chains:

These chains are used for hoisting and hauling purposes. The hoisting and hauling chains are the following two types:

i. Chains with oval links: The links of the type of chain are of oval shape as shown in fig. The joint of each link is welded. The sprockets which are used for this type of chain have receptacles to receive the links. Such type of chains are used only at low speeds such as in chain hoists and in anchors for marine works.

ii. Chain with square links: The links are this type of chain are square shape as shown in fig. Such type of chains are used in hoists, cranes, dredges. The manufacturing cost of this type of chain is less than that of chain with oval links, but in these chains, the kinking occurs easily on overloading.

2. Conveyor Chains:

These chains are used for elevating and conveying the materials continuously. The conveyor chains are the of the following two types:

i. Detachable or hook joint type chain

ii. Closed joint type chain

The conveyor chains are usually made of malleable cast iron. Theses chains don’t have smooth running qualities. The conveyor chains run at slow speeds of about 3 to 12 km.p.h.

3. Power Transmitting Chains:

These chains are used for transmission of power, when the distance between the centres of shafts is short. These chains have provision for efficient lubrication. The power transmitting chains are of the following three types:

i. Block Chain: A block chain as shown in below fig. It is also known as bush chain. This type of chain was used in the early stages of development in the power transmission.

It produces noise when approaching or leaving the teeth of the sprocket because of rubbing between the teeth and the links. Such type of chains are used to some extent as conveyor chain at small speed.

ii. Bush Roller Chain: A bush roller chain consists of outer plates or pin link plates, inner plates or roller link plates, pins, bushes and rollers. A pin passes through the bush which is secured in the holes of the roller between sides of the chain. The rollers are free to rotates on the bush which protect the sprocket wheel teeth against wear.

iii. Inverted Tooth or Silent Chain: An inverted tooth or silent chain is designed to eliminate the evil effects caused by stretching and to produce noiseless running. When the chain stretches and the pitch of the chain increases, the links ride on the teeth of the sprocket wheel at a slightly increased radius.