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design of transmission systems v2 Cheat Sheet (DRAFT) by

design of flat belts, v belts, worm, helical, bevel, spiral gears, gearbox, clutches, brakes

This is a draft cheat sheet. It is a work in progress and is not finished yet.

design procedure for v belt

belt drives unit 1

belts are used to transmit power bwtween two shafts by means of friction. this type of drives is called flexible drive cause a flexible belt is superi­mposed between the driving and driven shaft.
belt drive is not a positive drive.
the common types of belt drives include, flat and v belts.
- flat belts transmit power over a consid­erable distance like in belt conveyors, whereas v belts are used in shorter distance rangelike in electric motors

repres­ent­ation of the belts

flat and v belts difference

  

adv and dis of flat over v belt and vice versa

flat belts advantages
disadv­antages
v belts advantages
disadv­antages
1. cheap and easy to maintain.
power transm­itting capacity is very low
forece of friction between the contact surfaces are high due to wedge action.
ratio of cross sectional height to pulley diameter is large
2. can be used as a clutch by making a simple provision of shifting the belt from a tight ot loose pullry and vice versa
velocity ratio is low
have short center distance
due to above condition, bending stress is induced
different velocities can be obtained
occupy more space due to larger dimensions
permits high speed reduction
creep is high and efficiency is low
they can be used for long center distances upto 15m.ef­fic­iency is mre
  
smooth and quiet operations at high speeds since v belts are endless
   
drive is positive cause the slip is negligible due to wedge action
=> wedge action:
The biggest operat­ional advantage of a V-belt is the wedging action into the sheave groove. This geometry multiplies the low tensioning force to increase friction force on the pulley sidewalls.
  

belt constr­uctions

properties of belt materials
(i) The belt material should have high coeffi­cient of friction with the pulleys.
(ii) The belt material should have high tensile strength to withstand belt tensions.
(iii) The belt material should have high wear resist­ance.
(iv) The belt material should have high flexib­ility and low rigidity in bending in order to avoid bending stresses while passing over the pulley
**leather belts have high coeffi­cient of friction and conseq­uently, high
power transm­itting capacity.

*There is a specifi c term ‘ply’ of the belt. In order
to make a practical thick belt, the layers of belt
material are cemented together, These layers are called ‘plies’ of belt. Belts
are specifi ed according to the number of layers or
plies, e.g., single­-ply, double-ply or triple-ply belts.
The power rating of the belt is also specifi ed per ply
of belt, **
  

joining belts

methdos for joining the belts
1. laced joints
2. cemented joints
3. metal fastners