Just like belts, a chain drive is another method of transmitting mechanical power from one point to another. But it’s often used to convey power to the wheels of vehicles.
Chain drives are also called drive chains or transmission chains that often convey power by a roller chain passing over a sprocket gear with teeth. These teeth mesh with the holes in the chain links.
In this reading, we’ll explore what chain drive is, its applications, components, diagrams, types, and how chain drive works. Its advantages and disadvantages will also be discussed.
What is a Chain Drive?
A chain drive is a way of transmitting mechanical power (rotational motion) from one place to another. Chain drives are used apart from transmitting mechanical power but also for conveying goods, as well as lifting and dragging objects. However, the power is said to be output when the chain is rotating.
Chain drives can also be seen as a series of connected links using pin joints. It consists of endless chains wrapped around two or more sprockets.
Typically, chain drives are used where the distance between power produced and where it’s transferred is less. However, some designs and types of chain drives are used to transfer power for longer distances.
A power transmitting in a chain drive is very effective, that is, no power is lost, unlike a belt or rope drive where some percent of slip must occur. Also, the speed ratio in chain drives remains constant, making it a better choice when compared with a belt drive.
Finally, a chain drive runs over a wheel called a sprocket which is designed with several teeth around its circumference. Although not all chains require a sprocket to run over.
Applications
Below are the various applications of a chain drive:
- Chain drives are used for power transmission.
- It’s used for lifting loads and conveying materials.
- Woodworking machinery finds great use of this component.
- A chain drive is used in material handling equipment.
- It’s used in vehicles such as cars, motorcycles, bicycles, lorries, etc.
- Agricultural machinery or equipment makes good use of a chain drive.
Related: What is Belt and Pulley? Their Diagram & Working
Components and Diagram of Chain Drives
The image below contains the diagram and components of a basic chain drive.
Classification of Chain Drives
Chain drives can be classified into three types based on their applications. Classification of chain drive includes:
- Load lifting chains
- Power transmission chains, and
- Hauling chains.
Load Lifting Chains
These types of chain drives are used for suspending, rising, or lowering loads in material handling operations. Link chains are the most popular types of these types of chains. The chain is beneficial as they have good flexibility in all directions, they are noiseless, the design is simple and easy to manufacture, and they can work on low-diameter drums and pulleys.
Power Transmission Chains
Power transmission chains are used for transmitting power from one shaft to another. The limitations of link chains are that they operate at low speeds, sudden failure can occur, prone to overload, and jerks, and it has a heavyweight.
Hauling Chains
Hauling chains are used for carrying materials continuously by sliding, pulling, or carrying.
Types of Chain Drives
The types of chain drives are explained based on their classification. Below are the various types of chain drives and their functions:
Hoisting chains
In normal terms, a hoist is a mechanical device that is used for lifting or lowering a load. It’s used for shifting heavy goods from one place to another in a workstation. So, the chain is a mechanical device used in performing its operation known as a hoist chain drive. The chains are strong enough to handle heavy weight. The hoist types of chain drives are further classified into two categories:
- Oval-link chain drive:
Overlinks are the common types of chain used in a hoist, it consists of various oval links joined to each other. The chain types are also known as coil chains. Although square link types of chains are also used, kinking occurred so easily due to high loading. This chain is only used at low speeds. The figure below shows an oval link chain.
- Stud-link chains:
A stud-link chain drive is used to minimize the deformation and link or tangle easily. The chain is made of round bars or studs, fit inside the oval-link chain to provide more strength to the chain. The types of chain drives are used in a ship to move its anchor up and down. It is also used in some crane hoists where a very high amount of load needs to be lifted.
Conveyor Chains
A conveyor chain drive is commonly used in a conveyor. This conveyor is a mechanical device that is used to move materials from one place to another. The chain drive is well-shaped, which is why it can easily run over sprockets. These chains are made of malleable cast iron and are used in low-speed machinery. The limitation of this chain is that its motion is not smooth, and there are chances of wear and tear.
These types of chain drives are further categorized into two types:
A detachable or hook joint conveyor chain drive – is used in a conveyor where the length between power transmissions is short.
Closed-end pintle conveyor chain drive – this type of conveyor chain drive consists of a barrel and link. It’s made in a single casting which is then heat-treated to offer higher strength.
Power transmission chain drive
The power transmission chain drive is used to offer rotational motion from one shaft to another. it’s made of steel which is sometimes heat-treated to resist wear and tear to some extent. These types of chain drives have greater accuracy and can easily run over sprockets.
Power transmission chains are further categorized into three types:
· Blockchain:
Block transmission chains are used in low-speed areas and will create noise due to sudden contact between the sprocket and chain. It’s also used in some low-speed conveyor machines.
· Roller chain:
The components of roller chain drives consist of a bush, inner link, pins, outer plate, inner plate, and rollers. A bush along with a roller is fitted inside both the plates then a pin is passed through both ends of the roller to fasten it. the chain is generally made of steel.
These rollers are free to rotate inside the bush so that when it contacts the sprocket wear and tear will be minimized. Its operation is soundless, wears less compared to that of blockchains, and is used in any circumstance like high-speed power transmission devices, like a motorcycle. It can serve longer if proper lubrication is maintained.
- Silent chain or inverted tooth chain:
these types of chain drives are also used in high-speed power transmission areas just as the previously mentioned one. But these types do not have any roller, it’s accurately shaped which makes it easily sit and run over the sprocket. lubrication is a key factor of these types of chains otherwise it will wear and tear out.
Roller chain
Conveyors, wire- and tube drawing machines, printing presses, vehicles, motorcycles, and bicycles are all examples of home, industrial, and agricultural machinery that use this sort of chain to transmit mechanical power.
A roller chain is made up of a succession of short cylindrical rollers connected by side links. A toothed wheel called a sprocket drives it. It is a power transmission system that is simple, dependable, and efficient.
The diameter of these chains is usually less than the height of the link plates. When the chain engages the sprockets, the link plates act as guides.
Chains can also be used as a guide to support material carried on rails or routes, which is common in conveyors and bucket elevators. Both driving and conveyor applications use roller chains.
The single-strand standard series roller chain is the most popular driving chain. These chains’ power rating capacities cover a broad range of drive load needs. Multiple-strand roller chains are used to increase power capacity without altering the pitch or linear speed of the chain.
Flat-top Chain
Flat-top chains are commonly used on conveyors, with the slat conveyor being the most common application. A series of steel top plates with hinge-like barrels curled on each side make up the Flat-top chain. To form a joint, pins are placed through the barrels.
These serve as both bearings and beams. Pins are held in place in the barrels of one top plate by press fits or headings but are free to articulate in the barrels of the following link.
To keep the connecting pin in one of the top plate’s barrels, it’s frequently knurled or expanded on one end. As a result, a continuous length of flat-top chain is created. Only conveying is the purpose of the flat-top chain.
Engineering Steel Chain
Engineering steel chains were first developed in the 1880s for challenging conveying applications. Conveyors, bucket elevators, and tension linkages all use engineering steel chains.
There are only a few that are used in drives. Tensile loads, various types of wear, lubrication, and the environment are the key design issues for these chains.
When building an engineering steel chain, the most significant parameters to consider are the following. Conveyor chain wear includes joint wear, roller and bushing wear, as well as sidebar and track wear.
Silent Chain
The silent chain, also known as the inverted tooth chain, is made up of a succession of toothed link plates attached to joint components in such a way that they can flex freely between pitches.
Silent chains are made up of stacked rows of flat link plates with gear-like shapes that contact sprocket teeth in the same way that a rack engages a gear, as seen in the diagram. One or more pins hold the links together at each chain joint, allowing the chain to stretch.
Silent chains from various manufacturers are typically unable to be joined. Silent chains are utilized in a wide range of industrial applications that demand a small, high-speed, smooth, low-noise drive.
High-performance silent chains come in a variety of diameters, pitches, and widths, and are utilized on extremely high-speed drives that demand outstanding smoothness and quietness. These chains are typically used in industrial equipment that requires extreme smoothness.
Leaf Chain
The purpose of leaf chains is to elevate rather than transmit power. Tensions are high, but the pace is slow. Normally, the chains only work on a sporadic basis. Tensile loads, joint wear, and link plate and sheave wear are all important factors to consider while designing leaf chains.
Leaf chains are not compatible with sprockets since they are designed to run over sheaves and have no provision for engaging a sprocket. Because leaf chains are frequently used to carry enormous loads, they must have a high yield strength and not be permanently stretched when doing so. The most prevalent application for leaf chains is on lift trucks.
Below are some other common types of chain drive:
Automobile Chain Drive
A chain-drive system in a vehicle transfers power from a differential to the rear axle. Chain drives were a prominent power transfer device in the early days of automobiles. With its rigid Hotchkiss, Driveshaft, and universal joints, it became a popular alternative to the Système Panhard.
Driveshafts and universal joints are more difficult to design than chain drives. It allows the suspension to react to bumps more effectively since there is less unsprung weight at the rear wheels. This would result in a smoother ride for the automobile.
Bicycle Chain Drive
The majority of bicycle chains are constructed of ordinary carbon or alloy steel; however, some are nickel-plated to prevent rust or for aesthetic reasons.
The key feature that defined the safety bicycle, which was launched in 1885 and featured two equal-sized wheels, from the “high wheeler” style of bicycle, was chain drive. The popularity of chain-driven safety is still a common component of modern bicycle design.
The efficiency of a bicycle chain is high because it shifts the center of the pressure away from the axle, decreasing stress on the bearings and lowering friction in the inner wheel. It was discovered that a higher chain tension was more efficient.
Related: What are Bearings? Their Diagram and How it Works
Working principle
Chain drives are perfect for small center distances and can be used up to 3 meters in most circumstances, but up to 8 meters in extreme cases. Chain drives may transmit up to 100 kW of power and have a peripheral velocity of up to 15 m/s. It’s possible to have an 8:1 velocity ratio.
The fundamental problem of belt and rope drives is that the velocity ratio does not remain constant and fluctuates due to slip. Because chain drives are positive drives, they don’t slip, hence the velocity ratio is constant.
Bicycles, motorbikes, rolling mills, agricultural machinery, machine tools, conveyors, coal cutters, and other power transmission applications all use chain drives. A chain drive is made up of two wheels called sprockets and a chain. The sprockets are toothed wheels that are fitted with an endless chain.
Advantages and Disadvantages of a Chain Drive
Advantages:
Below are the advantages of the various types of chain drive:
- Multiple shafts can be driven from a single chain.
- They are used for both long and short distances.
- Fire hazard does not happen.
- They are compact and have small overall dimensions.
- Its working is not affected by temperature or environmental conditions.
- A chain drive can be easily installed.
- Abrasive conditions can be withstood.
- Slapping does not occur.
- They can operate in wet conditions.
- They have a very high working efficiency of about 96%.
Disadvantages:
Despite the good benefits of chain drives, some limitations still occur. below are the disadvantages of a chain drive in its various applications.
- A chain drive cannot be used on an application that requires slippery.
- Frequent lubrication is required.
- Less load capacity is obtained compared with gear drives.
- Its operation can be noisy and vibrations might occur.
- They cannot be used where precise motion is required.
- Housing is required.
- They are not suitable for non-parallel shafts.
- Adjustment is required when the chain slack.