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