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2. As the speed of chain drive has been continually raised
during recent years the majority of chain drives on most modern
internal combustion powered rigs now use chains of 2,5-in. pitch
or less rather than the long pitch API chain.
3. On most high speed drilling rig drives it is advisable to
provide force-feed lubrication to the chain from the inside of the
drive so that centrifugal force will throw the lubricant through the
chain and not off the chain.
4. During installation the alignment of roller chain .drives
should be rechecked.
5. If it becomes necessary to use less strands of chain on a
drive designed for a greater number ul strands it will be necessary
to replace or reverse the sprockets when the full multi-strand chain
can he obtained and installed.
6. The general maintenance lubrication procedures
mentioned in regard to roller chains are applicable to silent chains.
7. V-belts are driven by the action of the sheave grooves
upon the sides of the belt.
8. As a result of the important usage of V-belts in the oil
fields, the API has developed considerable valuable data
concerning their selection, application and use.
9. If the tension section of a belt is ruptured by installation,
accident or use, the condition is evidenced by a necked down
section, and such a belt should be removed from the drive.
10. Guards should be kept in position and properly ventilated
and drained.
11. Gears are used most where compactness of design, quiet
operation and large speed variations and ratios are required.

Exercise 3. Say whether the following statements are true
or false
1. The roller chain used in drilling rig main power
transmission drives is usually manufactured in accord with the
requirements of the American Standards Association.

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