Page 190 - The Tribology Handbook
P. 190
One-way clutches
Table 6.2 Characteristics of one-way clutches
Max. Indexing
TYPe Max torque freewheeling accuracy Cost
speed
Ratchet and Pawl IO3 Nm low poor low
Roller clutch 5 X 104Nm moderate good low
Needle roller clutch IO' Nm high good low
Sprag clutch lo6 Nm high good high
Wrap spring clutch 5 X 10'Nm low moderate low/moderate
The above characteristics are for commercially readily available units. Larger, higher torque versions of all types are
possible as special designs. For very high torques and power a better alternative is a self-synchronising clutch, described in
section 5.
The graph below shows the approximate relationship between torque capacity and freewheeling speed for the various
types.
10 000
1
100 1000 10 000 50 000
FREEWHEELING SPEED (Revhin)
Figure 6.1 Approximate torque and freewheeling speed limitations for commercially available clutches
B6.2
