Minimizing Cost
It is usually more economical to purchase “stock” sizes of chain and sprockets
rather than ordering non-stock or made to order sizes. This is often true, even
when it is necessary to buy stock components that are somewhat larger than
required.
Minimizing Noise and vibration
Use smaller pitch chains and sprockets with larger numbers of teeth to reduce
noise and vibration.
Sprockets
Increasing the number of teeth in sprockets will decrease noise and prolong
sprocket life. Whenever possible sprockets should have a minimum of 21 teeth.
Drive Ratios
Ratios of 12:1,or greater, are possible but above 8:1 it is usually desirable to
acheive the ratio in two steps.
Shaft Center Adjustment
Whenever possible it is desirable to provide adjustable shaft centers. This allows
for chains to be re-tensioned as they wear and is particulary important in drives
where one shaft is located vertically above the other. Typically the amount of
adjustment should equal at least 1% of the center distance.
Chain Width
The use of a wider than recommended chain will result in a more rugged drive,
with reduced chain stresses, and potentially longer drive life.
Shaft Center Distance
The distance between shafts should be great enough that the chain wraps the
small sprocket at least 120 degrees. Generally, center distances should not
exceed 60 pitches.
Chain Length
Whenever possible chain length should be an even number of pitches. An odd
number of pitches requires the use of an offset section which weakens the chain
and increases cost.
Tensioning Devices
An adjustable idler sprocket can often be used to maintain chain tension on
drives where the shafts are fixed. In some instances, tensioning arms or pads
can be pressed against the back of a chain to maintain chain tension. Consult
with the chain manufacturer before employing these devices since some two pin
chains can be damaged by their use.
Drive Enclosures
Fully enclosed drives, with proper lubrication, are desirable for maximum service
life and personnel safety.
Non-horizontal And Vertical Shafts
Drives that use non-horizontal shafts often work best with side guide chain and
an automatic tensioner. Consult Ramsey for specific recommendations. |
