Tech Tip: Chain Drives

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What is the difference between Double Strand sprockets and Double Single sprockets?

Double Strand sprockets will run a single strand of double strand chain whereas Double Single sprockets will run two strands of single strand chain, e.g., D40B21 will run #40-2 riveted chain. DS40A21 will run 2 separate strands of #40 riveted chain.
  

What is the typical allowable amount of chain wear elongation in a simple drive or conveyor application?  

1.5-2% is typically considered the wear elongation limit for roller chain.

What causes galling of pins and bushings, and how can it be prevented?

Galling is the micro-welding of the pin and bushing bearing surfaces to each other under high pressure.  When the joint goes around the sprocket, the micro-welds tear out; leaving wear.  Proper chain selection is the key to avoiding elongation.

What would be the advantage of having sprockets "Keyed in Line in Pairs" versus purchasing a stock sprocket that is "Kw Centerline of Tooth"?

Stock sprockets are normally keyed centerline of tooth, but there is a tolerance of +/- 1 degree so any two sprockets could be as much as 2 degrees different in the extreme tolerance situation. When keyed in-line in pairs, the sprockets are clamped together and keyed at the same time, ensuring they are perfectly matched.

Will Heavy Series Double Strand ANSI Chain work on standard Double Strand sprockets?

Double strand sprockets will run a single strand of double strand chain whereas double single sprockets will run two strands of single strand chain. For example D40B21 will run #40-2 riveted chain. DS40A21 will run two separate strands of #40 riveted chain.

Can you operate British Standard Chain using ANSI standard sprockets?

In some cases, yes. The sizes that can be used are as follows: RS10B can use #50; RS12B can use #60; RS16B can use #80; RS20B can use #100. Please note this is a one-way interchange only. You would not be able to operate ANSI standard chain with British Standard sprockets.

Will double pitch sprockets work with oversize roller double pitch roller chain?

No. Oversize roller double pitch chain requires a special type of sprockets to run the chain, e.g. C2062H riveted chain would need to use #2062 series sprockets.

Is it possible to use single pitch sprockets when using double pitch roller chain?

Yes, but there are some constraints. 1) The chain must be non-oversize roller type. 2) The sprocket must have over 30 teeth for this to apply. For example, C2060H riveted chain using 60B32 sprocket.

Difference between an AL and BL Leaf Chain

AL series chain uses standard roller chain component dimensions for pin diameter and plate thickness. For example, AL8 has component dimensions similar to RS80 chain while the BL series utilizes thicker side plates and a pin diameter of the next chain size up.

Why would you choose a multiple-strand instead of using a larger pitch chain?

Space and design constraints must be considered.  A wide chain can often use a smaller diameter sprocket to transmit the same amount of horsepower for a given speed (RPM). This is important for tight spaces.

Leaf Chain Application 

Leaf chain or the counter-balance chain is widely used on forklift trucks, machine tools, elevators, oven doors, and any other lifting or balancing applications.

Chain Drive Lubrication

Proper lubrication of chain drives will ensure that the chain drive wears properly.  The amount of lubrication and the type should be as specified by the manufacturer. Lack of lubrication will result in metal moving against metal causing wear and heat.  Excessive lubrication could become a safety hazard and a risk for fire. Changing drive speed could result in a need to change the lubrication method and amount of lubrication needed.

Drive Speed Modification

When changing the speed on a chain drive, always be aware of the contact angle of the smaller sprocket in relationship to the larger sprocket. A minimum contact angle must be maintained so the chain does not jump the teeth on the smaller sprocket. If the contact angle will be too small, then you will need to increase the number of teeth on the smaller sprocket and the larger sprocket to get the ratio that you desire.

Chain Drive Safety

Chain drives, because of the moving of the chain and teeth on the sprockets, need to be enclosed.  Unenclosed drives pose a real safety hazard to all those who are around them. Normally, new drives will have the chain guarded by a cover or protective device. Over time, the guard or protective device may become detached or not put back in place after maintenance. Time should be spent checking to make sure that all chain drives are enclosed with a guard or protective device.

How to Double the Life of Sprockets

Extended pitch or double pitched chain has the same dimensions as regular chain except the pitch is double the standard. Double pitched chain usually have a 20 in front of the chain size, e.g., 2050 chain. Sprockets are made for double pitch chain and they have half the teeth as a regular sprocket for the same size regular chain. If a regular sprocket is used on a double pitch application, then only half of the teeth will come in contact with the chain.  So when every other tooth shows wear the user can just loosen the chain and rotate the sprocket until unused teeth are now engaged. This in essence will double the life of the sprocket. This only applies when the sprocket has an even number of teeth.

Proper environment for stainless steel chain versus coated chain

Corrosion resistant chain is best used in food processing plants, fertilizer plants, waste management plants and any other applications that go through routine wash downs with water or any chemicals. Coated chain is suggested to be used in wet and moderately corrosive environments, stainless steel is best in very corrosive environments.

The information provided in Tech Tips is not meant to be all-encompassing, but rather to draw attention to and provide information about the particular subjects covered. All suggestions and recommendations contained in Tech Tips are based upon information that is believed to be accurate to the best of the experience and knowledge of PTDA’s contributing members, but are made without guarantee or representation as to results. PTDA and Tech Tip contributors expressly disclaim any warranties or guaranties, express or implied, as to the accuracy or completeness of any information published in Tech Tips, and disclaims and makes no warranty that the information in Tech Tips will fulfill any of your particular purposes or needs. PTDA and Tech Tip contributors disclaim liability for any personal injury, property, or other damages of any nature whatsoever, whether special, indirect, consequential, or compensatory, directly or indirectly resulting from the publication, use of, application, or reliance on Tech Tips.