190 Machine Drawing
dharm
d:\N-Design\Des13-1.pm5
Table 13.1 Roller chain dimensions. Dimensions are in mm
Designation Pitch Roller Pin Width Plate
BIS dia, Dr dia, Dp W depth, H
05 B 8.0 5.0 2.3 3.1 7.04
06 B 9.525 6.35 3.31 5.9 8.14
08 B 12.7 8.31 4.45 7.85 11.69
10 B 15.875 10.16 5.08 9.85 14.26
12 B 19.05 12.07 5.72 11.7 15.95
16 B 25.4 15.88 8.27 17.1 20.8
13.4 Inverted Tooth or Silent Chains
These are high speed chains used for prime movers, power cranes, machine tools and pumps.
These chains are made-up of a series of toothed links assembled with pins in such a way that
the joint articulates between adjoining pitches (Fig. 13.2).
Link plate
Rivet
Fig. 13.2 Silent chain
13.5 SPROCKETS
These are used for mounting on flanges, hubs or other devices (Fig. 13.3). Although the sprockets
are normally machined from grey iron castings, they are also available in cast steel or welded
construction. Smaller sprockets, known as pinions are of plate type; larger sprockets, known
as wheels, have hub extensions.
13.6 Design of Roller Chain Drives
The design of roller chain drive consists of the selection of the chain and sprocket sizes. It also
includes the determination of the chain length and centre distance. The limiting factor of
chain drive is based on revolutions per minute of the pinion sprocket. Multiple width roller
chains transmit greater power at higher speeds. They also substantially reduce noice factor
because of their smooth action.
It is a general practice to use a minimum size of sprocket of 17 teeth in order to obtain
smooth operation at high speeds. The normal maximum number of teeth is 120. The practice
indicates that the ratio of driver to driven sprockets should not be more than 6. Centre distances
must be more than one half of the diameter of the smaller sprocket plus one half of the diameter
of the larger sprocket. Eighty times pitch is considered the maximum.
The chain length is a function of number of teeth in both sprockets and of centre distance.
In addition, the chain must consists of integer number of pitches; preferably with an even number.
