Chain Drive
A chain drive system is a part of the drivetrain that transmits torque from the engine or motor to the differential. A chain and sprocket requires lubrication and a tensioner. Chain analysis is incredibly complex and often teams will not need to dig into the analysis beyond a cursory level. If the needed information is not supplied by the chain supplier, please see The Complete Guide to Chain produce by the chain manufacturer Tsubaki[1]. For a shortlist of diagnostic pointers, see the html plaintext "CHAIN & SPROCKETS" writeup on the Honda Bros website[2].
Contents
System Design
Chains can be easily lengthened or shortened using quick release links.
Sealing
Sealed chains use o-rings to seal in a lubricant, great for daily driving. Also used in racing applications. Very common in motorcycle shops. Non-sealed requires more frequent lubrication application and are commonly used for motocross or low mileage applications.
Sizing
There are many write-ups online for how to understand chain sizing and how to size your chain[3].
Tension
- Main page: Tensioner
A mechanism is needed to apply tension to the chain. This enables the chain to be installed and removed when slack, and to take up the slack in the chain as it stretches. If the chain is too loose when running, it can fail catastrophically. If it too tight, it will wear out faster and will draw too much power from the drivetrain. Usually chain tension is measured by chain sag, or it deflects from a straight line. It is recommended to follow manufacturer recommendations for chain tension. A good rule of thumb is 2% of distance between sprockets[1][4].
Sprockets
Sprockets are made of steel, aluminum, or titanium and can replaced to change the final drive ratio. Sprockets can be bought or easily made by laser-cutting, water-jetting, or CNC machining.
As the number of teeth decrease, the sprocket will approach a polygon instead of a circle. This is called the polygon effect or chordal action and results in a variation in speed output (Imagine driving on square wheels)[1][5]. Typical sprockets don't ever go under 11 or 12 teeth for 35 and 40-series chains.
Drivetrain Shield
Chain drives have specific shielding rules in FSAE covered in T.5.2.7 (link to rules) (what about FS?).
Failure Modes
If there is excessive sprocket wear, improper chain tension, improperly installed quick release, no lubricant, or if the chain drive is not in the same plane there WILL be a failure. Chain failures can be extremely dangerous for both the vehicle and nearby people. (more on failure modes/design flaws?)
+No slip possible in chain drive without failure https://www.myodesie.com/wiki/index/returnEntry/id/3058#Chain%20Drive%20Advantages
References
- ↑ 1.0 1.1 1.2 Kanehira, M. The Complete Guide to Chain, Tsubaki, 1995
- ↑ http://homepage.eircom.net/~hondabros/CHAIN_MAINTENANCE.html
- ↑ https://www.partzilla.com/blog/how-to-measure-motorcycle-atv-chains
- ↑ https://www.cisco-eagle.com/vector/504/adjusting-the-drive-chain
- ↑ http://chain-guide.com/basics/2-2-1-chordal-action.html
