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.