Machinist

[Lawrence London <lfljvenaura@gmail.com>]

http://www.visusa.com/belt_tracking01.htm

 

Belt Tracking

Pulley Crowns

Crowning one or several pulleys in a belt system is the most common way of tracking a belt.  For flat power transmission belts and narrow conveyor belts (up_to_8_in.), a radius crown is used.  For wider conveyor belts, a trapezoidal crown is typically applied.  Note: Never utilize an apex crown!

Radius Crown Specifications for Flat Belt Pulleys

A radius crown represents a great way to track a belt.  Dimensionally, it does not take a big crown height in order for the belt to track properly, and exceeding the seemingly small amounts below will actually do more harm than good! In a system with multiple pulleys, crown the pulleys that turn the same way.

Standard Radius Crown Heights  h
Pulley Face Width Wp	Pulley Diameter  D
	1-6	6-12	12-28	28-40	40-60	>60
in	in	in	in	in	in	in
1-5	0.031	0.047	0.051	0.067	0.078	0.098
5-10	0.039	0.051	0.059	0.078	0.090	0.110
10-16	0.043	0.055	0.063	0.087	0.098	0.118
>16	0.047	0.059	0.078	0.098	0.118	0.137

convert to metric units

The min. pulley face width W_p = (belt width W_b x 1.1) + 0.5 in.

The max. belt width W_b = (pulley face width W_p - 0.5 in) / 1.10

Trapezoidal Crown Specifications for Conveyor Pulleys

Pulley Diameter  D	Crown Height  h
in	in
1 to 2.75	0.012
2.75 to 4	0.017
4 to 6	0.022
6 to 8	0.026
8 to 11	0.034
11 to 14	0.042
>14	0.045

convert to metric units

 

Note:	The cylindrical part of the pulley Wc is half of the belt width Wb.
	Also, it is recommended for the pulley width Wp to be approximately 10 to 20% wider than the belt width Wb for the pulley crown to function properly.  For pulley widths less than 8 in., use a radius crown and refer to the flat belt pulley specifications above.