2. Dr. Muhammad Wasif
Qualifications
B.E. ‐ Mech. Engg. NED UET 2000‐2003
M. Engg. ‐ Mfg. Engg. NED UET 2005‐2007
Ph.D. (CAD/CAM) CU, Canada 2009‐2013
A New Approach to CNC Programming for Accurate Multi‐axis Face‐
Milling of Hypoid Gears
Experiance
Hinopak Motors Ltd. Prod. Exec. 2004‐2005
NED UET (IMD) Lecturer 2006‐2007
NED UET (IMD) Director PDC 2006‐2007
NED UET (IMD) Asst. Prof. 2007‐2013
2ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
3. Belt Drives – Review
• In power transmissions, use of belts, simplify the machine design
and reduce the cost.
• Is far more economical than buying a motor to run at the speed
required by the driven equipment.
• Due to flexibility, it can absorb a good amount of shock and
vibration.
• It can take care of some degree of misalignment between the
driven and the driver machines and long distance power
transmission.
3ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
4. V‐Belts : Advantages
• Transmit greater amount of power with higher velocity ratio.
• Usually made of cotton, ryon or nylon impregnated with rubber.
• A single V‐belts is less efficient than a flat belt due to the wedging action
b/w belt and pulley (high friction), but multiple v‐belts can be used to
transmit higher power.
• V‐belts are longer in life due to seamless design (no joint).
• V‐belts are used for short center distance, i.e. compactness.
• V‐belts are manufactured in standard lengths.
• The groove angle of a sheave is made somewhat smaller than the belt‐
section angle. This causes the belt to wedge itself into the groove, thus
increasing friction.
4ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
5. V‐Belts : Limitations
• V‐belts cannot be used with large center distance.
• V‐belt’s pulleys are complicated in design and hence expensive.
• Not suitable for constant speed applications due to creep.
• Less durable than the flat belts.
• Speed limit of v‐belt drives are between 5 to 50m/s due to the
design of groove in pulley.
5ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
7. V‐Belts
• Pitch length is defined as the circumferential length of the belt
at the pitch width of the belt (width at the neutral axis).
• The value of pitch width remains same for any type of the belt.
(S.I.)
7
9. V‐Belts
• Non standard pitch length and center distances can be
calculated using;
• Relation between T1 and T2 is
2.3 /
9ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
11. Timing Belts
• It is made of rubberized
fabric coated with a nylon
fabric, and has steel wire
within to take the tension
load.
• It has teeth that fit into
grooves cut on the
periphery of the pulleys
• No slip and negligible
stretch.
• Can be used with wide variety of speed.
• Higher efficiency (97‐99%)
• Five standard types are available according to the applications.
11ME‐205, Elements of Machine design and dynamics, conducted by Dr. Muhammad Wasif (Asst. Professor ‐ IMD, NEDUET)
12. Refernces
12
• R.S. Khurmi, G.K. Gupta, 2005, A text book of machine design, New Dehli‐ India,
EURASIA PUBLISHING HOUSE.
• R. G. Budynass, J.K. Nisbett, 2005, Shigley’s Mechanical Engineering Deisgn, New
York –USA, McGraw Hill.
• R. L. Mott, 2004, Machine Elements in Mechanical Design, USA, Pearson Prentice‐
Hall.
• R. L. Norton, 1996, Machine design an integrated approach, NJ USA, Prentice‐Hall.
• B. J. Hamrock, B. O. Jacobson, S. R. Schmid, 1999, Fundamental of Machine
Elements, New York –USA, McGraw‐Hill.
• U. C. Jinbal, 2010, Machine Design, India, Pearson .
• R. O. Parmley, 2005, Machine devices and components, USA, McGraw‐Hill.
