Difference between revisions of "Tensioner"
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==Idler== | ==Idler== | ||
Another sprocket or pulley is used to add tension to the chain or belt. It does not add any torque to the system and freely spins. A common implementation is the secondary sprocket on a bicycle derailleur. | Another sprocket or pulley is used to add tension to the chain or belt. It does not add any torque to the system and freely spins. A common implementation is the secondary sprocket on a bicycle derailleur. | ||
| + | |||
| + | An Idler is a passive tensioner and should not need servicing. Due to the passive nature, fine control is difficult. | ||
==Eccentric== | ==Eccentric== | ||
| − | An eccentric chain tensioner holds the driven sprocket with a circular mount. The driven sprocket is held off of the neutral axis such that when the mount is turned, the driven sprocket is moved closer or farther from the drive sprocket. The circular mount may be retained by friction around the circumference or by shear pins to the larger structure. A frictional retention method allows for infinite adjustability. Shear pins mean the mount can only be tensioned in discrete steps, but the use of a vernier scale style hole pattern allows incredibly fine control. | + | An eccentric chain tensioner holds the driven sprocket with a circular mount. The driven sprocket is held off of the neutral axis such that when the mount is turned, the driven sprocket is moved closer or farther from the drive sprocket. The circular mount may be retained by friction around the circumference or by shear pins to the larger structure. A frictional retention method allows for infinite adjustability. Shear pins mean the mount can only be tensioned in discrete steps, but the use of a vernier scale style hole pattern allows incredibly fine control. The main benefit of the eccentric mount scheme is the ability to tension the chain without removing any parts from the car, or adding new ones. |
Eccentric mounts tend to be larger than other mounting schemes and thus may be inherently stiffer. By necessity, they require multiple moving parts which can drive additional complexity and design time. | Eccentric mounts tend to be larger than other mounting schemes and thus may be inherently stiffer. By necessity, they require multiple moving parts which can drive additional complexity and design time. | ||
| + | |||
| + | ==Footballs== | ||
| + | Utilizing "footballs" with eccentric mounting holes allows the sprockets to be moved further away by flipping the football within the mount itself. Unlike a traditional eccentric mount, the chain cannot be tensioned without taking the mount apart and swapping fittings. | ||
| + | * MIT used in 2006 | ||
| + | * See Lightweight Torsen Style Limited Slip Differential and Rear Driveline Package for Formula SAE by Tony Scelfo | ||
==Turnbuckle== | ==Turnbuckle== | ||
Often implemented on a swing arm type design. | Often implemented on a swing arm type design. | ||
-play<br />-wear<br />-packaging<br />-rigidity[citation needed]<br />+infinite adjustability<br />can be done as a differential screw <ref>https://en.wikipedia.org/wiki/Differential_screw</ref><ref>https://www.halfbakery.com/idea/Differential_20Turnbuckle</ref> | -play<br />-wear<br />-packaging<br />-rigidity[citation needed]<br />+infinite adjustability<br />can be done as a differential screw <ref>https://en.wikipedia.org/wiki/Differential_screw</ref><ref>https://www.halfbakery.com/idea/Differential_20Turnbuckle</ref> | ||
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==Toothed== | ==Toothed== | ||
Revision as of 18:51, 27 February 2023
A tensioner is a mechanism that necessary to a belt or chain drive to ensure long term proper function. Without correct tension, the drive system may fail catastrophically.
Contents
Tensioning Systems
There are a few ways to create tension in a belt or chain drive system. You can increase the distance between the drive and driven sprocket such as in the shimmed or eccentric systems. Another method is to lengthen the path of the chain as in the idler method.
Shims
Shims are one of the simplest methods of tensioning the chain. A shimmed system only requires a differential mount that has a vertical split that can be bolted together. By inserting shims between the front and rear halves of the differential mount(s), the differential can be moved further away. The shims can be made of any stiff material. Anecdotally these are frowned upon by design judges, but your mileage may vary.
If correctly designed, shims can be the stiffest option for tensioning the chain as the entire system will be held in compression, there are no threads, and no moving parts. The shimmed design also presents an incredibly cheap option.
Guide
Chain guides use a durable low friction material to squeeze the chain into tension. This is most commonly used for timing chains (kept lubricated inside the engine) and sometimes on bicycle[1].
Idler
Another sprocket or pulley is used to add tension to the chain or belt. It does not add any torque to the system and freely spins. A common implementation is the secondary sprocket on a bicycle derailleur.
An Idler is a passive tensioner and should not need servicing. Due to the passive nature, fine control is difficult.
Eccentric
An eccentric chain tensioner holds the driven sprocket with a circular mount. The driven sprocket is held off of the neutral axis such that when the mount is turned, the driven sprocket is moved closer or farther from the drive sprocket. The circular mount may be retained by friction around the circumference or by shear pins to the larger structure. A frictional retention method allows for infinite adjustability. Shear pins mean the mount can only be tensioned in discrete steps, but the use of a vernier scale style hole pattern allows incredibly fine control. The main benefit of the eccentric mount scheme is the ability to tension the chain without removing any parts from the car, or adding new ones.
Eccentric mounts tend to be larger than other mounting schemes and thus may be inherently stiffer. By necessity, they require multiple moving parts which can drive additional complexity and design time.
Footballs
Utilizing "footballs" with eccentric mounting holes allows the sprockets to be moved further away by flipping the football within the mount itself. Unlike a traditional eccentric mount, the chain cannot be tensioned without taking the mount apart and swapping fittings.
- MIT used in 2006
- See Lightweight Torsen Style Limited Slip Differential and Rear Driveline Package for Formula SAE by Tony Scelfo
Turnbuckle
Often implemented on a swing arm type design.
-play
-wear
-packaging
-rigidity[citation needed]
+infinite adjustability
can be done as a differential screw [2][3]
Toothed
- See wollongong 2012
Diagrams
Shimmed
Guide
Idler Sprocket or Pulley
Eccentric
Offset Footballs
need diagram of toothed style chain tensioner
Examples
Curtain University's shimmed chain tensioner in 2012
Tennessee Tech's guide chain tensioner in 2019
Michigan State's eccentric chain tensioner in 2019
Wollongong's toothed chain tensioner in 2012
need example images of football style, idler style
