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Hamrock • Fundamentals of Machine Elements
Chapter 19: Flexible Machine Elements
Scientists study the world as it is; engineers create the world that has
never been.
Theodore von Karmen
Hamrock • Fundamentals of Machine Elements
Figure 19.1 Dimensions, angles of contact, and center distance of open flat belt.
Flat Belt
Hamrock • Fundamentals of Machine Elements
Figure 19.2 Weighted idler used to maintain desired belt tension.
Weighted Idler
Hamrock • Fundamentals of Machine Elements
Figure 19.3 Synchronous, or timing, belt.
Synchronous Belt
Hamrock • Fundamentals of Machine Elements
V-Belt in Groove
Figure 19.4 V-belt in sheave groove.
Hamrock • Fundamentals of Machine Elements
Table 19.1 Overload service factors f
1 for various
types of driven unit.
Overload Service Factors
Hamrock • Fundamentals of Machine Elements
Table 19.2 Recommended minimum pitch diameters of pulley for three belt sizes.
Table 19.3 Recommended pulley dimensions in inches for three electric motor sizes.
Pulley Design Considerations
Hamrock • Fundamentals of Machine Elements
Table 19.4 Arc correction factor for various angle of loss in arc of contact.
Arc Correction Factor
Hamrock • Fundamentals of Machine Elements
Table 19.5 Power ratings for light-duty V-belts. (a) 2L section with w
t = 1/4 in and h
t=1/8 in.
Power Ratings for V-Belts
Hamrock • Fundamentals of Machine Elements
Table 19.5 Power ratings for light-duty V-belts. (b) 3L section with w
t = 3/8 in and h
t=1/4 in.
Power Ratings for V-Belts (cont.)
Hamrock • Fundamentals of Machine Elements
Table 19.5 Power ratings for light-duty V-belts. (c) 4L section with w
t = 1/2 in and h
t=9/32 in.
Power Ratings for V-Belts (cont.)
Hamrock • Fundamentals of Machine Elements
Center Distance for V-Belts
Table 19.6 Center distances for various pitch diameters of driver and driven pulleys. (a) 3L type of V-Belt.
Hamrock • Fundamentals of Machine Elements
Center Distance for V-Belts (cont.)
Table 19.6 Center distances for various pitch diameters of driver and driven pulleys. (b) 4L type of V-Belt.
Hamrock • Fundamentals of Machine Elements
Figure 19.6 Two lays of wire rope. (a) Lang; (b) regular.
Figure 19.5 Cross-section of wire rope.
Wire Rope
Hamrock • Fundamentals of Machine Elements
Table 19.7 Wire rope data.
Wire Rope Data
Hamrock • Fundamentals of Machine Elements
Table 19.8 Minimum safety factors for a variety of wire rope applications.
Minimum Safety Factors
Hamrock • Fundamentals of Machine Elements
Figure 19.7 Percent strength loss in wire rope for different D/d ratios.
Figure 19.8 Service life for different D/d ratios.
Effect of D/d Ratio
Hamrock • Fundamentals of Machine Elements
Table 19.9 Maximum allowable bearing pressures for various sleeve materials and types of rope.
Allowable Bearing Pressures
Hamrock • Fundamentals of Machine Elements
Figure 19.9 Various parts of rolling chain.
Figure 19.10 Chordal rise in rolling chains.
Rolling Chains
Hamrock • Fundamentals of Machine Elements
Table 19.10 Standard sizes and strengths of rolling chains.
Strength of Rolling Chains
Hamrock • Fundamentals of Machine Elements
Chain Power Ratings
Hamrock • Fundamentals of Machine Elements
Rolling Chain Data
Table 19.12 Service factors for rolling chains.
Hamrock • Fundamentals of Machine Elements
Dragline
Figure 19.11 Typical dragline.