There are a bunch of belt mechanisms available for the construction of mechanisms. Chain drive mechanisms are also very good alternatives to belt drive mechanisms that have very specific features, advantages, and disadvantages. Here, we explain;
Table of Contents ;
- Advantages and uses of chain drive mechanisms,
- Types of these mechanisms,
- The design procedure and guide of these mechanisms with calculators,
- Maintenance and lubrication of chain drive mechanism,
- Applications that we use these systems.
What is Chain Drive Mechanism?
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These mechanisms are very important to power transmission mechanisms used in such types of machinery. Typical chain drive includes link plates that they linked with rollers. So, these rollers are attached to a link plated on both sides with pins. With the respective alignment of this assembly, they obtain long chains.
They assemble these long chains with toothed-around pulleys called sprockets. So, they can carry very high powers and loads with them which is their most important advantage.
There are lots of kinds of chain types available for various kinds of applications. The most common type of chain drive is the ‘roller chain’. Other types of chain drives are also included different designs of link plates and linkings.
We use roller chains generally in load-carrying applications such as conveyors, part support chains or conveyor slats, etc. Chains are linked to each other with different attachments to obtain these types of machinery.
For roller chains, the distinctive information is the ‘pitch length’ which defines the distance between adjacent pins in these systems. Like other machine elements, roller chains also have standards that are provided by chain drive manufacturers.
In roller chain drive catalogs, maximum tensile strength information is also provided. In the design of these systems, it will be safe that the mechanism has stressed 1/10 of this tensile strength value.
Standards of roller types are numbered starting from 40 to 240 in general manufacturer catalogs. This number indicates the pitch of a chain drive. You must divide this number by 180 to find out the pitch length of this chain in inches. To indicate the heavy-duty roller types, there can be ‘H’ before the number of chain drives such as 40H. For heavy-duty roller chain drives, the thickness of link plates is higher.
Types of Chain Drive Mechanisms
For different kinds of applications, there are different types of chain drive mechanisms. Among the most common ones;
- Power transmission
- Hoisting and hauling
types of them.
Power Transmission Types
Chain drives are very common in power transmission systems. We can give different kinds of power transmission applications of them.
In power transmissions, we use these systems between two shafts. Also, we use them between the power generotor which can be an electrical motor or internal combustion engine.
Also, the main advantage of the chain drives in power transmission over the gears, if the distance between the shafts is very high, we can use these types of mechanisms to carry power to other sections.
Conveyor systems are very common in such industries. They are very important in material handling and movement. So, they use different kinds of chain drive systems in the movements of these conveyor systems.
Also, there are different configurations of conveyor types. These conveyor types are very stable and smooth systems for heavy material handling systems.
Hoisting and Hauling Types
In lifting applications of heavy materials, hoisting systems are very common systems. We can easily lift very heavy weights. So, we use chain drive systems in these types of hoisting and hauling systems.
How To Design Chain Drive Mechanism?
If you need to obtain a chain drive mechanism inside machinery, you need to define the input information to start the design. Your design must ensure that;
- There will be no galling of links because of the loads applied to chains.
- To obtain the required number of lifecycles for fatigue which is generally resulted from the stress applied to the chain at the tighter side of the chain drive.
- Life of rollers that are worn in the engagement of sprocket teeth during service.
All the design parameters of chain drives are related to these situations.
Because of the moment increment, when the number of teeth increases at a constant velocity, the power that is transmitted is increased. In terms of the quietness of chain systems, smaller teeth of chains must be used on a larger diameter of sprockets.
Like in v-belt and synchronous belt drive mechanisms, several chain strands can be used in one mechanism. But this does not mean that the transmitted power capacity will increase proportionally. In general, the transmitted power capacity of a system with the increasing strands of chains increases with this ratio;
- 1.7x for two strands of chains,
- 2.5x for three strands of chains,
- 3.3x for four strands of chains.
You need to select a proper service factor for your mechanism according to different parameters;
- Working conditions,
- Working environment,
- Sensitivity of your application etc.
In general, given data in standard catalogs are provided with a safety or service factor of 1.
The optimization of chain velocity and sprocket velocity is very important. There is an optimum speed for a specific chain drive mechanism. At lower speeds, fatigue because of the fluctuating stress at the tight side on-chain is an important effect. At higher speeds, the galling of rollers is a very important factor. So, an optimum speed for chain drive must be obtained.
The speed ratio between small and big sprockets must be lower than 7. You can also design it with much higher speed ratio numbers. But, in the application, it will be safe to design two or more steps of chain drives for bigger speed ratios.
In most applications, the minimum sprocket teeth number must be higher than 17. This is because the power transmission is very hard in terms of strength at a high rpm greater than 100. The big sprocket must not be bigger than 120 teeth.
The center distance between sprockets must have between the 30-50 pitch lengths of chains. The adjustable center distance to adjust the sag of the slag side is preferred also.
Horizontal alignment of sprocket and chain drives is more proper. And it is recommended that the right side of the chain must be at the upper side of the system.
Determine the length of the chain by using this calculator;
Chain Drive Length Calculator
This calculator provides you to calculate the required chain length for your application. What you need to do is, just enter the center distance C(meters, millimeters, inches…) and the number of teeth of the small sprocket(N1), and the number of teeth of the big sprocket(N2). Click on the ‘Calculate!’ button to see the required chain length. To make another calculation, click on the ‘Reset’ button. Then re-enter the values.
This calculator uses the formula below. You can check your calculation with this formula;
If the pitch of the chain is known, say ‘up for it, the required diameter of the sprocket can be calculated with this calculator also;
Sprocket Diameter Calculator
Enter the pitch of the selected chain for the chain drive mechanism in terms of millimeters or inches. Enter the number of teeth of your sprocket then click on the ‘Calculate!’ button.
The angle of contact between the smaller sprocket and chain must be bigger than 120 degrees. You can calculate the angle of contact between a smaller sprocket and a bigger sprocket by using this calculator again;
Angle of Contact Calculator For Sprockets And Chain
θ1 is the contact angle between the smaller sprocket and the chain. θ2 is the contact angle between the big sprocket and the chain. You need to just enter the center distance(C), the small sprocket diameter(D1), and the big sprocket diameter(D2).
The formulae for the angle of contact between small and big sprockets and chains;
Once you calculated the required diameter and number of teeth of sprockets and the length of chains, you need to select the closest standard parts of them from standard catalogs provided by sprocket and chain manufacturers.
The units of entered values must be consistent with each other to obtain correct results from calculators and calculations.
Selecting the Right Type of Chain Drives for Different Applications
To select a proper chain drive mechanism for a system, we need to consider a bunch of parameters. After defining these parameters we can select a proper one. Probably, you have lots of catalogs in your hand to select the proper systems. So, after defining these parameters, it will be very easy for you to select a proper mechanism.
The speed of the application is a very important parameter. You need to define the maximum speed of your system. So, this will be the first parameter that you need to define. After defining the speed, the available types of chains will get narrow.
The type and layout of the system in the selection of chain drives is also a very important parameter. For example, you need to use these systems in non-parallel shafts. So, there are different types of chain drives that you can use in these systems.
Also, you can directly use them in engine power transmissions. So, you need to look at the types of power transmission systems.
Total Load on the System
The size and the type of the chains are also dependent on how much load they will be exposed to. So, you need to define the total load that you will use these systems. In chain drive catalogs, you will probably find the different types of them for different applications.
Lubrication of chain drive systems is also a very important thing to consider. There are different types of lubrication. You need to select the lubrication type that you will use in your chain drive systems. Also, you can find detailed information about the lubrication recommendations in catalogs.
Lubrication Of Chain Drives
In chain drive mechanisms, there is great interaction between metal parts dynamically which leads to very high frictions and wearing of metals that constitute the chain system. Furthermore, sprockets and pins are open to wearing without enough lubrication.
Chain lubricants are generally petroleum-based, which has optimized viscosity to cover all the required chain and sprocket parts to prevent wearing and decrease the friction between them.
In general, there are three types of lubrication systems are applied to chain drive systems;
- Oil pump lubrication: Like in modern car engines, lubricant is jetted via a pump on a chain drive system to supply enough lubrication to the chain system.
- Manual lubrication: The operator of certain machinery which has a manual lubrication system, lubricates the chain system between specific periods. Lubrication is done with special brushes generally.
- Bath lubrication: In this system of lubrication, a part of the chain is dipped inside a sump of lubricant which is generally beneath the chain drive system. This dipped part of the chain takes the required lubricant to the different parts of the chain drive system.
Advantages and Disadvantages of These Systems
Like the other kinds of systems, there are advantages and disadvantages to chain drive systems. You need to consider these facts about these systems before using them in your applications.
- The most important advantage of these systems, they can transfer power over long distances. This is the main reason that we use chain systems.
- The accuracy motion is another important parameter in the chain drive systems. There is no slip between the chain drive systems and the shafts. So, they are more accurate if we compare them with the belt mechanisms.
- Compactness is also another important parameter. They can fit in very narrow spaces.
- Low friction with lubrication is another important advantage of these systems.
- In general, the use of an encloser is important because of occupational safety. Because every time there is a risk of damage and jump to the environment. And also, it is very dangerous for the people.
- There is no tolerance for misalignments in chain drive mechanisms.
- The lubrication of these systems must be very strict and efficient.
- Noise and vibration are the most common problems in the operation of the chain drive systems.
General Applications That We Use Chain Drives
The use of chain drive systems is very common in engineering. Also, there are different kinds of applications because of their advantages.
Bicycles and Motorcycles
In bicycles and motorcycles, the power must be transferred over long distances. So, the use of chain drive systems is very common. The general type of these systems is the roller chains.
They are very efficient in these systems because the gear change is much easier on bicycles and motorcycles.
In industrial conveyors, the use of chain drive systems is very common. Because the power from an electrical engine is transferred by the chain system to the rotating conveyor system. And they are very accurate systems for material handling.
Industrial systems also require heavy-weight applications. And chains drive systems are very good at carrying very high weights.
Internal Combustion Engines
In internal combustion engines, you know that the general application is the timing belt mechanisms. But in high power systems, they generally use chain systems instead of timing belt systems. Because they work more accurate and danger of a breakdown in higher powers and torques is less common.
This article can be a very good guide to designing your chain drive systems. All the aspects of these systems can be explained like above.
There are different types of systems that we use in hosting, lifting, industrial moving, and power transmission systems. So, selecting the right one is a very important business for an engineer.
Also, we need to consider the advantages and disadvantages of these systems over other systems. These are the very important facts about these systems to consider before selecting a type.
Lubrication is also a very strict subject in these systems. Because lubrication is very important to obtain efficient and noise-free systems. Otherwise, the system will collapse.
We use chain drive systems in different kinds of applications.
Finally, do not forget to leave your comments and questions about these systems below.
Above all, Mechanicalland does not accept any responsibility for the calculators that are provided for the user. As a good engineer, you need to check your calculations several times with hand calculations.
Take a look at the other engineering calculators available in Mechanicalland!
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Source Of Formulas: https://www.pearson.com/store/p/machine-elements-in-mechanical-design/P100001430091
FAQs About Chain Drive Systems
There are three types of these systems; power transmission types, conveyor types, and hauling-hoisting types of chain drives. They are very different applications that we use in engineering systems.
Chain drive mechanisms are very efficient systems for power transmission between long distances. So, they are very common in internal combustion engines, motorcycles, and bicycle applications.
There are different advantages and disadvantages of these systems. The biggest advantage is, that they can transfer power and torque between very distant places. Also, the most important disadvantage of these systems is the requirement for very strict lubrication.
There are different kinds of machines that use these systems; bicycles and motorcycles, industrial conveyors and internal combustion engines are the most common applications of the chain drive mechanisms.
The most important difference is, belt drives do not have mechanical attachment with shafts like the chain drives. So, chain drives provide much higher accuracy in the power transmission.
The most important advantage of belt drives, they do not require strict lubrication. But with chain drives, we can transfer much more higher torques and power with better accuracies. So, the answer to this question changes according to the application.
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