Chain drives are essential for every mechanic, allowing us to easily remove or replace parts without dismantling the entire machine.
It consists of two parallel shafts connected by a series of gears; the outer ring rotates at half speed compared to the inner ring, allowing the gear teeth to mesh smoothly.
However, there are different types of chain drives, each serving its purpose, and we’ll discuss some of them in this article.
What is a Chain Drive?
A chain drive is a mechanism that transmits torque from a rotating shaft to another shaft without slipping. It connects the crankshaft of an internal combustion engine to the camshaft.
In automotive applications, chain drives are widely used because they provide superior performance compared to belt drives.
They are also cheaper to manufacture and maintain. The chain comprises interlocking link plates called “teeth.” These teeth are shaped like small wedges, each tooth being slightly wider than the gap between adjacent teeth.
As the chain moves around the sprocket, the teeth slide into the gaps between the sprocket teeth, creating friction.
The friction causes heat, which melts the plastic material forming the teeth. If the melted plastic cools too quickly, the chain will seize up. To prevent seizing, manufacturers use lubricants to keep the chain moving smoothly.
Chain drives are generally less efficient than belts because they do not allow continuous rotation. However, they offer greater flexibility and durability, making them ideal for heavy-duty applications such as mining equipment.
Different Types of Chain Drives
Conveyor Chain Drive
A conveyor chain drive is a machine that moves materials along a path.
This device consists of several interlocking metal segments called teeth. Also, these teeth attach via a pin that passes through each tooth.
A chain wraps around the pins, so when the chain rotates, it also causes the teeth to rotate. As a result, the chain moves the teeth forward.
The chain itself must be fastened to the teeth. For this purpose, there is usually a wheel that engages into the groove of the teeth.
Then, the wheel mounts on a shaft, which runs parallel to the axis of the teeth.
If you look closely, you will notice that the teeth are slightly offset from the centerline of the shaft. This allows the chain to turn freely without slipping.
You’ll find chain drives in manufacturing plants. In factories, people use conveyor belts to transport raw materials and finished goods.
Power Transmission Chain Drive
The power transmission chain drive is prominent among the different types of chain drives.
You’ll find this chain drive in industrial equipment such as automobiles, motorcycles, tractors, lawnmowers, construction vehicles, farm implements, etc.
Also, you can find it in heavy industry, where they often transmit torque and force from one machine component to another.
This chain drive uses a single row of teeth with no overlap; the teeth are attached to a central hub with a circular cross-section.
Also, the teeth are evenly spaced apart, and their shape is similar to those on a bicycle chain.
Hoisting and Hauling Chain Drive
The chain hoist is probably the best-known type of lifting machine.
In fact, it is the most common piece of industrial equipment found in garages, workshops, and construction sites.
A typical example is a hand chain hoist, where one end of a long chain attached to a load is lifted by pulling on the opposite end of the same chain.
The weight of the load being lifted is transferred to the chain via the block.
Once the load reaches the desired height, the operator releases the tension on the chain, and the load falls onto the ground.
A motor powers the chain hoist and rotates the drum or hook.
The rotation speed determines how fast the chain winds around the drum or hook. When the chain is fully wound, the motor stops.
Another chain hoist type uses electric motors to rotate the drum or hook. These machines work in oil refineries, petrochemical plants, and chemical manufacturing facilities.
However, people prefer electric chain hoists over mechanical ones because they do not require constant maintenance.
The third type of chain hoist is pneumatically operated; they are common in industries because they are quiet and efficient.
However, they are relatively expensive compared to mechanical and electric versions.
Types of Chains
1. Roller Chain
The roller chain is one of the oldest types of machine chains still in use today. It is a form of roller chain that uses bushings and rollers to transmit power.
The main advantage of the roller chain over other chain forms is that it does not require lubrication.
As the name suggests, a roller chain uses bushings and roll pins to transfer power.
The rollers are attached to the bushings, which slide inside the link plates.
In addition, there are no moving parts such as gears or bearings, making the roller chain resistant to wear and tear.
2. Silent Chain
Silent chains consist of a series of tooted link plates assembled on joint parts in a way that allows flexible movement between each pitch.
They use a unique method of connecting the individual link plates into a chain. Also, the silent chain comprises several link plates arranged side by side in parallel rows.
Each plate is like a gear with a tooth profile. When the chain runs around a pinion, the teeth mesh with the teeth of the pinion and transmit power.
The silent chain mounts on a shaft via a pair of bearings, allowing it to rotate freely.
Because the chain does not make contact with the outer surface of the shaft, there is no friction loss during rotation.
In addition, since the chain does not rub against the inner wall of the bearing, wear occurs slowly over time.
3. Flat-top Chain
Flat-top chains are widely employed on conveyors, most fundamentally utilized on the particular sort of slat conveyor called a flat-top chain.
A flat-top chain comprises several top plates hinged together like doors. Each top plate contains a pinhole that allows pins to be inserted into the barrel of the adjacent top plate.
Then, the pins stay in position by pressing the end of the pin against the top plate.
When the pins are removed, the joints between the full plates allow them to move freely relative to each other.
The flat-top chain comprises a series of such joints. Generally, the chain comprises four sections, each consisting of three joints.
At the beginning and end of the chain, additional top plates usually serve as bearing surfaces for the rollers of the conveyor system.
4. Leaf Chain
Leaf chains are useful in many applications where transmitting power from one rotating member to another without meshing teeth is necessary.
They are usually helpful in heavy-duty equipment such as cranes, hoists, conveyors, etc.
The most common application is to use leaf chains to drive pulleys, drums, or spindles.
A typical example is a crane boom. In this case, the chain lifts the load, and the driving force transmits to the drum via a gearbox.
Another common application is in mining operations, where the chain drives the buckets of a bucket elevator.
The load goes into the mine shaft, and the driving force transmits to the bucket via a gearbox.
Conclusion
Different types of chain drives have come up over the years to meet different requirements.
Some of these designs are more efficient than others, but you’ll find all of them in various industrial sectors.
