Which tooth profiles and pitches can you produce for a custom timing belt?

Question

Accepted Answer

Direct answer: The main families are all covered: HTD curvilinear in 3M, 5M, 8M and 14M; STPD in S2M, S3M, S5M and S8M; metric trapezoidal T2.5, T5, T10 and T20; AT5, AT10 and AT20; and imperial MXL, XL, L and H. Double-sided belts are available in most of these pitches.

Rubber timing belt 196XL in imperial XL pitch — Imperial XL belt, one of the most common replacement pitches (196XL).

Profile families at a glance

Family	Common codes	Typical use
HTD (curvilinear)	3M, 5M, 8M, 14M	General power transmission, good load capacity
STPD (curvilinear)	S2M, S3M, S5M, S8M	Compact drives, lower noise than HTD at small pitches
Metric trapezoidal	T2.5, T5, T10, T20	Positioning and conveying, older European machines
AT (trapezoidal, wide)	AT5, AT10, AT20	Higher loads than T profiles, conveying with fixtures
Imperial trapezoidal	MXL, XL, L, H	North American machines, replacement duty
RPP-style (on request)	RPP5, RPP8, RPP14	High-speed drives where tooth engagement matters

Rubber timing belt S2M-124 in small STPD pitch — S2M for compact instrument and office-machine drives (S2M-124).

Matching a belt you already have

Measure the pitch precisely: distance between tooth centres, averaged over ten teeth or more.
Count the teeth and note the width. With pitch and tooth count, the profile is usually identifiable.
Compare with a known part number if the old belt has one, for example an 8M or S8M code.
Send photos of the tooth face and the belt marking. Brand names on the old belt are used only to identify a compatible profile; GOODLY is an independent manufacturer and supplies its own equivalent.
If the pulley is available, a tooth-profile photograph against a ruler is enough for most checks.

Choosing between similar profiles

HTD vs STPD

Both are curvilinear and not interchangeable on the same pulley. STPD suits compact, quieter drives; HTD carries higher loads on wider belts.

T/AT vs HTD

Trapezoidal T and AT profiles engage with more clearance and suit conveying with fixtures; HTD transmits more power for the same width.

Imperial vs metric

Imperial pitches such as XL and L cannot mesh with metric ones. Match the pitch system of the existing pulleys first, everything else second.

A new pitch may need new tooling, which affects cost and lead time on small quantities. Standard pitches moulded to your length and width are usually the faster route.

Rubber timing belt 337L-25 in imperial L pitch — L-pitch belt moulded to length for an American machine (337L-25).

Which profile does your machine need?

Send the belt code, tooth count and width, or photos of the old belt, to sales@goodlybelts.com. We will identify the profile, confirm the pitch and quote the custom belt.

Identify my belt