Page 276 - Analysis and Design of Machine Elements

Analysis and Design of Machine Elements
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As sliding velocities increase, low viscosity lubricant and oil spray with pressure are pre-
ferred. A higher viscosity lubricant or grease can be used for open wormgear drives.
References

1 Budynas, R.G. and Nisbett, J.K. (2011). Shigley’s Mechanical Engineering Design,9e.
New York, USA: McGraw-Hill.
2 Mott, R.L. (2003). Machine Elements in Mechanical Design, 4e. Prentice Hall.
3 Jelaska, D. (2012). Gears and Gear Drives,1e. NewYork, NY:Wiley.
4 Pu, L.G. and Ji, M.G. (2006). Mechanical Design, 8e. Beijing: Higher Education Press.
5 Juvinall, R.C. and Marshek, K.M. (2011). Fundamentals of Machine Component
Design,5e. NewYork, NY:Wiley.
6 Wen, B.C. (2015). Machine Design Handbook, 5e, vol. 1&2. Beijing: China Machine
Press.
7 Zhang, X., Wang, Z., Ji, D. et al. GB10085-88(1990). Basic Parameters of Cylindrical
Worm Gears. Beijing: Standard Press of China.
8 Hibbeler, R.C. (2006). Engineering Mechanics-Dynamics, 11e. Prentice Hall.
9 Hindhede, U., Zimmerman, J.R., Hopkins, R.B. et al. (1983). Machine Design Funda-
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Problems

Review Questions

1 For power transmission, why should the number of teeth of a wormgear be within
the range of 28–80?

2 Under what condition can a worm be placed on the top of or below a wormgear?
3 What will be the effect of sliding velocities on the worm transmission under poor
lubrication or under sufficient lubrication?

4 To improve heat dissipation capability, should the fan in a wormgear drive be
mounted on the worm shaft or on the wormgear shaft?

Objective Questions

1 The most effective method of improving the efficiency of a wormgear drive is___.
(a) to increase the modulus m
(b) to increase the number of thread of a worm
(c) to increase the worm diameter factor q
(d) to reduce the worm diameter factor q