Sheet Metal Tolerance Standards: April 2013

V Groove Pulley Material Selection

For generally purpose V groove pulleys are made by Grey Iron Casting IS: 210-1970

Grey Cast iron Material Grade and Properties
Code of Designation	Grades	Tensile strength	Transverse Test			Typical Applications	Note:
Code of Designation	Grades	Tensile strength	Breaking load Min, Kgf	Corresponding Transverse Rupture Stress Kgf/mm²	Deflection Min, mm	Typical Applications	Note:
FG 15	15	15	800	34.0	4.0	Parts Requiring no Special Grade for general Structural Purpose	Damping Capacity Decreases with increases in tensile strength
FG 20	20	20	900	38.2	4.5
FG 25	25	25	1000	42.4	5.0	Parts Subjected to severe strain such as cylinder parts, etc.
FG 30	30	30	1100	46.7	5.5
FG 35	35	35	1350	57.3	5.5	for extraordinary use
FG 40	40	40	1500	63.7	5.5	for extraordinary use

for general purpose pulley we can select FG 20 for which the equivalent grade is

SAE 111

DIN 1691/GG22

BS 1452/Gr 12

CSN 42 24 21

V Groove Pulley Design

V groove Standard dimensions as per IS 3142

How to select V groove pulley standard dimension like width, depth, Pitch line, etc is discussed below.

Based upon the belt used for transmission the pulley dimension are selected there are generally different Types of V belt A, B, C, D, E

the below drawing shows the Dimensions of the Sectioned double groove v Pulley.

And the values are taken from standard as shown in the table below

a sample pulley dimensions are given below

The following procedure will tell,

How to select general tolerance for machined components.

1. For discussion a bearing housing is considered with inner diameter turned to ø60mm.

To provide a tolerance to the diameter we have to select what kind of fit to be used.
Let us considered the load acting on the bearing inner ring is varying as shown below.

Table 1.1

For our case considered the shaft is transmitting Power therefore inner ring is rotating.

From Table 1.1, third operating condition the fit is selected as interference fir for Housing
Now from Table 1.2, for normal & heavy Duty the tolerance Class is selected as N7

Table 2

From Table 1.3, the Tolerance is selected as -0.039/-0.009

Table 3

Sample dimensioning and Tolerances for a housing

How to select the general machining tolerance as per IS 2102 is discussed below.

2. For discussion a stepped shaft is taken as shown below.

From Table 2.1, given below Tolerances for linear dimensions can be arrived

Table 2.1 General Tolerance for Linear Dimensions

From Table 2.2-3, given below Tolerances for Fillets, Chamfers & Angles dimensions can be arrived

Table 2.2-3 General Tolerance for Fillet, Chamfer and Angular Dimensions

From the Given Table the tolerance for shaft for general Machining is selected and shown below (Note: this for a general machined shaft, cases where the shaft is going to be seat in bearing, a similar procedure as of housing has to be followed.)