Type of timing pulley

[zedman]

There's a few type of timing pulley, XL,L, H, XH, HTD, T and so on. What does it mean by these thing? I can see in catalog, such as 10 XL 037 or 28-14M-40. please help me with this. Thanks.

 

[Philrock]

You're right - there are many kinds of timing belts, and it's hard to keep track of them all.

XL, L, H, XH, stand for, respectively, extra light, light, heavy, and extra heavy. These are trapezoidal tooth forms and have been around for decades. This is an inch based system.

All systems described below are metric.

HTD stands for high torque drive. This is a curvilinear tooth form and has been around for quite a while, but not as long as the trapezoidals.

Other curvilinears include Gates Poly Chain GT and Gates Poly Chain GT2. These are well established, but have not been around as long as the above mentioned forms. They are popular because of their relativley high power capacity density.

T, and other forms are trapezoidal, and vary in relationships of tooth thickness to pitch, materials of construction, etc. These are widely used for conversion of rotary motion to linear motion.

There are herringbone forms, which have the advantage that no flanges are required.

Generally speaking, belts of one form can not be used with pulleys of another form.

If you really want to know all the differences and understand the part numbers, you'll have to study the manufacturers' catalogs carefully. If you have a new application for power transmission, Poly Chain GT2 is hard to beat.