Timing Belts (Synchronous Belts)
Timing Belts (Synchronous Belts)
Timing belts – also called synchronous belts – use molded teeth that mesh with grooved sprockets to transmit power without slip, holding exact shaft timing at any load. Texas Belting stocks thousands of timing belts in Houston, TX across HTD, GT, AT, T and classical trapezoidal pitches, plus open-end stock and matching sprockets and pulleys.
Shop timing belts by family
On this page: Browse by pitch · HTD vs GT vs classical · Open-end belts · Sprockets & pulleys · Identify your belt · Houston supplier · Common mistakes · FAQ
Browse timing belts by pitch
Pitch is the tooth-to-tooth spacing and is the first thing to match – a belt only meshes with a sprocket of the same pitch and profile. Timing belt part numbers usually read pitch length, then pitch code, then width: 1200-8M-30 is a 1,200 mm long, 8 mm pitch belt, 30 mm wide. Every link below opens live inventory filtered to that pitch.
| Family | Pitches | Tooth spacing | Typical use |
|---|---|---|---|
| Classical inch (trapezoidal) | MXL, XL, L, H, XH, XXH | 0.080 in to 1-1/4 in | Legacy US machinery, light positioning drives |
| HTD curvilinear | 3M, 5M, 8M, 14M, 20M | 3 to 20 mm | The dominant industrial profile; 8M and 14M carry most power drives |
| GT round-tooth | 3MGT, 5MGT, 8MGT, 14MGT | 3 to 14 mm | Higher capacity and registration than same-pitch HTD |
| Super Torque | S2M, S3M, S5M, S8M, S14M | 2 to 14 mm | STPD drives common on Japanese OEM equipment |
| Metric AT (reinforced) | AT5, AT10 | 5 and 10 mm | Polyurethane linear and positioning drives |
| Metric T (trapezoidal) | T2.5, T5, T10 | 2.5 to 10 mm | European polyurethane conveying and positioning |
Tooth-spacing figures are industry-standard nominal pitches. Match pitch and profile to the sprocket before ordering.
HTD vs GT vs classical: which profile?
Classical trapezoidal teeth (MXL through XXH) came first and still run on huge amounts of legacy US equipment. HTD's deeper curvilinear tooth carries substantially more load at the same width, which is why 8M and 14M dominate modern industrial drives. GT profiles refine the curvilinear tooth further for higher capacity and better registration on the same nominal pitches.
Replacement rule: match what the sprockets are cut for. In the 8 mm and 14 mm pitches, GT belts generally run in HTD sprockets and are sold as replacements – but smaller GT pitches, HTD belts in GT sprockets and classical belts in either are not drop-in swaps. When in doubt, send us the sprocket part number and we will confirm the right belt. If you are designing a new drive rather than replacing a belt, start from the load and speed, not from what happens to be on the shelf.
Open-end and polyurethane timing belts
Linear actuators, gantries, door drives and long conveying axes use open-end (open-length) timing belt: straight polyurethane belt with steel or aramid cords, cut to length and clamped at each end rather than welded into a loop. We stock open-end belt alongside our endless inventory – see the open-end timing belt page for profiles and ordering, or call with your axis length and profile.
Sprockets, pulleys and bushings
A timing belt is half the drive. Sprockets must match the belt's pitch and profile, clear its width, and mount to the shaft – usually through a taper-lock or QD-style bushing. Flanged sprockets keep the belt tracking on drives with any misalignment. Browse timing pulleys and sprockets, and use the sprocket selection guide to work from tooth counts and ratios to a part number.
Identify the timing belt you have
- How to identify your belt – profile, pitch and width from a belt in hand.
- How to measure your belt – tooth counting and length rules.
- Belt cross reference – convert Gates, Continental, Bando and other part numbers to stocked equivalents.
- Belt length calculator – from shaft centers and sprocket sizes to the belt you need.
Timing belt supplier in Houston, TX
Texas Belting & Supply stocks its synchronous-belt inventory in Houston, and most stocked sizes ship same day. We supply plants, machine builders and repair shops across the Texas Gulf Coast and ship nationwide. For width cuts, hard-to-find pitches or full drive packages, call (888) 203-2358 to confirm availability.
Common timing belt selection mistakes
- Matching pitch but not profile. An 8 mm HTD, GT or S8M belt will drop onto the wrong 8 mm sprocket – and strip under load. Match both.
- Reading the part number backwards. Most families run length-pitch-width (1200-8M-30), but some series put width first. Confirm against tooth count before ordering.
- Replacing the belt but not inspecting sprockets. Hooked or shark-finned teeth chew up a new belt quickly. Check tooth profiles at every belt change.
- Over-tensioning. Synchronous belts need far less tension than V-belts – enough to prevent tooth jump, no more. Over-tension kills bearings and belts.
- Ignoring width. Capacity scales with width. A narrower belt of the same pitch is not an equivalent, even if it fits the sprocket.
- Prying the belt over a flange. That kinks the tension cords. Slacken the drive fully and slide the belt on square.
When to call instead of browse
- The belt is destroyed and unreadable – we can work back from sprocket tooth counts and centers.
- You need open-end belt cut, joined or clamped for a linear axis.
- You are converting a drive between profiles or need belt and sprockets quoted as a package.
Call (888) 203-2358 or send us what you have – photos, tooth counts and shaft centers are enough.
Frequently asked questions
What does 8M mean on a timing belt?
8M is an 8 mm tooth pitch in the HTD curvilinear family. A part number like 1200-8M-30 reads pitch length 1,200 mm, pitch 8M, width 30 mm. Divide pitch length by pitch to get the tooth count – 150 teeth in this example.
Are HTD and GT belts interchangeable?
In the 8 mm and 14 mm pitches, GT belts generally run in HTD sprockets and are sold as replacements. Smaller GT pitches and the reverse direction – HTD belts into GT-cut sprockets – are not guaranteed fits, and classical trapezoidal belts never interchange with either. Confirm profile against the sprocket before substituting.
How do I measure timing belt pitch?
Measure center-to-center between two adjacent teeth: 8 mm is 8M-family, 14 mm is 14M, 1/2 in is H, 3/8 in is L, 1/5 in is XL. Then count total teeth; teeth times pitch gives pitch length, the first number in most part numbers.
What is the difference between a timing belt and a V-belt?
A timing belt meshes teeth with a grooved sprocket, so shafts stay synchronized and nothing slips; a V-belt transmits power by friction in a smooth groove and can slip under shock. Use timing belts where registration or high efficiency matters, V-belts where cheap shock absorption does.
Can I replace an XL belt with an L belt?
No. XL is a 1/5 in pitch and L is 3/8 in – the teeth simply do not mesh with the other family's sprockets. Within the same pitch you can often go up in width for more capacity if the sprocket accepts it, but pitch and profile must always match the sprocket.
What are open-end timing belts used for?
Open-end belt serves linear motion: gantries, actuators, sliding doors and long conveying axes where each end clamps to the moving carriage or frame instead of joining into a loop. It is typically polyurethane with steel or aramid cords for minimal stretch over long spans.
Related products and guides
Need help matching a timing belt?
Send the numbers on the old belt, sprocket tooth counts, or shaft centers – we will confirm pitch, profile and width and quote same day.
Request a Quote Call (888) 203-2358Last updated: July 2026