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   Chains selected on the basis of "endurance limit" should be well lubricated to provide satisfactory service life. Although the frequency of chain joint action in such drives is low, and joint wear due to articulation should be low, the lubrication is needed due to the higher loads and to prevent corrosion.

Chain Length Calculations
Chain Length may be calculated from the following formulae:
  

Where C1 =

Center distance in number 
of pitches (links)
-- low ratios and long
centers.
  C2 =

Center distance in number
of pitches (links)
-- high ratios and short
centers.
  L =

Chain length in number of
pitches (links).
  N =

Number of teeth in
large sprocket.
n =

Number of teeth in
small sprocket.
P = Chain pitch.

   If the center distance is already fixed because of other factors, an idler sprocket may be used with not less than a three tooth wrap. When the idler is placed outside the closed span it should be placed nearer the small sprocket, and when inside the closed span it should be placed nearer the large sprocket The 6Z9 series product group in this catalog provides adjustable drive tighteners and idlers.

3.6 Lubrication 
Chain life will vary appreciably depending on the way the drive is lubricated. A properly lubricated chain can last more than 100 times as long as the same chain with poor lubrication.
    There are four basic types of lubrication for chain drives.

Type l -- Manual Lubrication -- Oil should be applied periodically with a brush or spout can, preferably once every 8 hours of operation.
Type ll -- Drip Lubrication -- Oil drops are to be directed between the linkplate edges from a drip lubricator at a rate of 5 to 20 drops per minute per strand of chain. The higher rate of flow should be applied to chains operating at rotative speeds approaching the limit for drip lubrication as shown on the horsepower rating tables. Precaution must be taken against misdirection of the drops by windage.
Type lll -- Bath or Slinger Disc Lubrication -- With bath lubrication, the lower strand of chain runs through a sump of oil In the drive housing. The oil level should reach the pitch line of the chain at its lowest point while operating. With slinger disc lubrication, the chain operated above the oil level. The disc picks up oil from the sump and deposits it onto the chain, usually by means of a trough. The diameter of the disc should produce rim

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