“v - belts” - design of machine element
TRANSCRIPT
Government Engineering College - BhujA presentation on subject of
Design of Machine Element
&
Topic is
“V - Belts”
UMANG PARMAR
Content……
Introduction to V-Belts.
Construction of V-Belts.
Types of Standard Cross Section of V-Belts.
Designation of V-Belts.
Advantages of V-Belts & Limitation of V-Belts.
Application of V-Belts.
Introduction…...• The cross section of V-belts are trapezoidal as shown in fig.
• When the two pulleys are close to each other, this type of belt drive isused.
• In V-belt drives, the pulleys are provided with grooves. It is known asgrooved pulley or Sheaves.
Construction of V-Belts…...
• As shown in fig. the central loadcarrying textile, nylon or steelcords.
• Surrounding rubber to transmitpressure from cords to sidewalls.
• And the outer wall is of fabricand rubber cover.
• The belts are made endless.
Construction of V-Belts…...
• The belts run in sheaves.
• The included angle for V-belt is 40ο .
• The pulley groove angle is 38o.
• The power is transmitted due to the wedgingaction between the belt and the side of thepulley groove.
• A clearance must be provided between thebottom of the belt and the pulley groove.
• To improve the capacity for large powertransmission, multiple belts may be used.
• For heavy duty application, 12 or more beltsmay be used for transmission.
Standard Cross Section of V-Belts……
• Based on cross sectional sizes, they are classified in six standard types.
• They are ‘Z’, ‘A’, ‘B’, ‘C’, ‘D’, ‘E’.
• The cross section area of the types are in ascending order.
Belt Section Width ‘b’ mm
Thickness ‘t’
mm
Min. pitch dia of
pulley ‘d’, mm
Correction ‘δ’
mm
Z 10 6 85 30
A 13 8 75 36
B 17 11 125 43
C 22 14 200 56
D 32 19 315 79
E 38 23 500 92
Designation of V-Belts……
• V-belts are designed by the symbol of cross section with the insidelength of the belt in mm.
• The relation between pitch length and inside length of V-belts iswritten as follow:
Pitch Length = Inside length + correction
(L) (Li) (δ)
• For example, E 3333 is having C-section belt and 3333 mm insidelength.
Advantages and limitation of V-Belts…Advantages
• They can transmit large powerdue to wedging action ascompared to flat belts.
• They have short centre distance,it helps in compact construction.
• At high operating speed, theoperation is smooth because thebelts are endless.
• The slip is negligible in V-belts.
• V-belt drive permit highreduction ratio up to 7:1.
Limitation
• The efficiency of V-belts is lessthan that of the flat belts.
• It fluctuates in the range of80% - 90%.
• They are costlier than flat beltsbecause of their design.
• They can’t be used to transmitthe power over the long centredistance.
Application of V-Belts……
• They are used in motors todrive blowers, compressors,machine tools, farm andindustrial machinery.
• Most common use of V-beltdrive in the internal combustionengine.
• The other uses of V-belt driveare in automobiles to drive theaccessories.
Thank you