Chain Drives

Definition A chain drives works very similar to a belt drive system. It works by mechanically transferring power from once source (known as the driver) to another source (known as the driven) This is achieved from sprockets rather than sheaves pulleys (used in a belt drive) A sprocket has visible drive points (teeth) on both the driver / driven locations and these locate with the links in the chain A chain drive has distinct advantages over a belt drive. https://en.wikipedia.org/wiki/Sprocket#/media/File:Chain.gif

Chain Drive Advantages Can transmit high power Able to work with accurate synchronising Centre distance between shafts is comparatively large Ability to work in areas where oil or grease is present Can work in severe operation conditions (wet, abrasive, hot) Lengths can be modified / set to required via link extraction / addition

Chain Drive Disadvantages Are less flexible than belt drives Require regular lubrication Backlash / slackness is evident Can be noisy Requires regular checks & maintenance

Roller Chain Types Simplex Duplex Triplex

Roller Chain Types Simplex roller chain is the type used for bicycle drive motion. It has single width row of rollers. It can be shortened or lengthened upon requirement. The chain must always run parallel between the 2 sprockets that it is positioned between, non parallelism of the chain and sprockets will cause wear and a reduction of the running efficiency of the drive. Repositioning of the sprockets is usually easily achieved via moving the sprocket position on the shaft. The tension of the chain must remain at the correct amount, too tight and it will not allow for expansion / contraction with temperature variations, too loose and the drive / driven sprockets could suffer with the chain riding over the sprocket teeth and causing them to wear into a hooked shape or the chain to actually jump over a tooth on the sprocket

Roller Chain Types Roller chains can also come in wider forms with 2 (Duplex) or 3 (Triplex) rows of rollers. The extra rows of rollers that a chain drive may have would it give it greater strength. Chain drives can come in other types in addition to Roller Chains, such as: Double Pitch Chains, Leaf Chains, Steel Drive Chains, Cast Drive Chains, Roller less Chain, Detachable Chain, Pintile Chain, Silent Chain

Leaf Chains consisting only of link plates and pins greater tensile strength than roller chains Ideal for lifting applications runs over sheaves rather than sprockets used as drive for machine tools, elevators & fork lift truck masts

Pintile Chain open barrel design eliminates material build-up in the root of the sprockets generally has smoother operation allows a wider range of applications including sugar mills, hay handling & wood processing

Silent Chain used for the camshaft drive of motorcycle and automobile engines have a very simple construction consisting of only plates and pins advantages include higher speed and power capacity, reduced noise and vibration & have greater efficiency

Chain Link Removal / Adjustment The length of a chain can be adjusted either by shortening or lengthening via removal or addition of its links. This can be achieved by using a link extractor

Roller Chain Construction Roller chain links are made of multiple parts, which are retained together in place by a clip which fits into a recess into each of the pins of the link

Sprockets Sprockets are attached to the main drive from the shaft and usually are driven via a key. The chain then wraps around the drive sprocket and provides motion to the driven sprocket. The tension between the two always has to remain correct

Chain Idlers / Tighteners Chain idlers are used to set and maintain the correct tension of a drive chain. These can run on either the outside or the inside of the chain Chain idlers can be either adjusted and set by fastening on a linear position or a radial one  

Chain Drive Lubrication There are a few reliable methods of ensuring the chain receives regular needed lubrication: Gravity fed oil drip Manual application of oil (brush on or oil feeder can) Manual application of grease (by spatula or aerosol spray) Splash method via passing through an oil tray Force fed oil

Care and Maintenance of Chain Drives Regular checks should be carried out on the chain drive system including: Regular checks for adequate lubricant supply Checks upon the chain to check for link condition (rollers & side plates) Periodic checks on the chain for stretching (sag) & tension Checks upon the sprockets to alignment and tooth wear / condition