Timing & Synchronous Belts
Where a V-belt transmits power by friction, a timing belt transmits it by tooth engagement. The teeth lock into the pulley grooves, so there is no slip and the rotational relationship between shafts is fixed — essential for indexing, positioning and conveying where registration matters.
Profiles fall into two broad families. Trapezoidal teeth (MXL, XL, L, H, XH, XXH) are the classic inch-pitch tooth form. Curvilinear teeth (HTD 3M/5M/8M/14M, plus GT and the S-profiles) use a rounded tooth that carries more load and runs quieter at higher torque. Pitch — the distance between teeth — sets compatibility.
Profiles and Sizes We Stock
Timing belts are specified by profile, length (pitch length) and width. Trapezoidal inch profiles are listed in inches; curvilinear metric profiles (HTD, GT, S) in millimeters. The ranges below reflect the pitch lengths we carry across each profile.
| Profile / Section | Typical Length Range | Notes |
|---|---|---|
| MXL Section | 3" – 104" | Trapezoidal, 0.080" tooth pitch — smallest inch profile |
| XL Section | 4" – 130" | Trapezoidal, 0.200" tooth pitch — light-duty |
| L Section | 7" – 141" | Trapezoidal, 0.375" tooth pitch — general-purpose |
| H Section | 11" – 250" | Trapezoidal, 0.500" tooth pitch — heavier drives |
| HTD 3M / 5M / 8M / 14M | 87 – 7616 mm | Curvilinear, 3–14 mm tooth pitch — higher torque, quieter |
| GT & S-profiles | 88 – 4508 mm | Curvilinear GT and S-profiles — low backlash |
Construction
Synchronous belts use a high-strength tensile cord — stranded fiberglass on standard lines, or aramid (Kevlar) on high-shock and high-load lines — set in a chloroprene or polyurethane body, with a tough fabric tooth cover that resists tooth wear and shear.
Pick the profile by pitch and the load family by tooth form. Trapezoidal profiles suit light-to-medium positioning and conveying; HTD and GT curvilinear profiles handle higher torque with less ratcheting. Aramid-cord versions resist shock and length growth on demanding, high-acceleration drives.
Typical Applications
Synchronous belts drive anything that needs slip-free, registered motion:
- Indexing, positioning and motion-control axes
- Packaging, printing and converting machinery
- Robotics and automation gantries
- Conveyors requiring registration or timing
- Pumps, compressors and HVAC where sync is required
Selecting and Measuring
Three numbers define a timing belt: pitch/profile, pitch length (often expressed as a tooth count), and width. A number like 600-5M-15 is a 5M curvilinear belt, 600 mm pitch length, 15 mm wide. An inch belt like 240XL037 is an XL belt, 24.0 inch pitch length, 3/8 inch wide. The teeth and the pulley must share the same pitch and tooth form.
If you are matching an existing belt, read the molded number off the back. If it is unreadable, we can identify the belt from pitch, tooth count and width — count the teeth and measure the tooth pitch and width, then call us.
Cross-References
D&D synchronous belts are built to standard pitch and tooth-form dimensions, so a belt of a given profile, length and width interchanges with the equivalent Gates PowerGrip (timing, HTD and GT), Continental Synchroforce, Dayco and Bando belt.
Search the number molded on your current timing belt and we will return the matching D&D part, confirming pitch, length and width.
Manufacturer names and part numbers are used for identification and reference only. Texas Belting & Supply and D&D Global are not affiliated with, sponsored by, or endorsed by Gates, Continental, Dayco, Bando, or any other manufacturer.
Frequently Asked Questions
What is the difference between a trapezoidal and an HTD timing belt?
Trapezoidal belts (MXL, XL, L, H) have flat-sided, angular teeth and are the classic inch-pitch form. HTD belts have rounded, curvilinear teeth that carry more load with less ratcheting and run quieter at higher torque. They are not interchangeable — the pulley tooth form must match the belt.
How do I read a timing belt number like 600-5M-15 or 240XL037?
600-5M-15 is metric: 5M curvilinear profile, 600 mm pitch length, 15 mm wide. 240XL037 is inch: XL profile, 24.0 inch pitch length (240 tenths), 3/8 inch (037) wide. The first part is length, the letters are the profile, and the last digits are the width.
Can I replace a fiberglass-cord timing belt with an aramid one?
Often yes, if the profile, length and width match. Aramid (Kevlar) cord resists shock and length growth, which helps on high-acceleration or high-shock drives. The tooth profile and pitch still have to match the pulleys exactly. Confirm the application before switching cord types.
Are D&D timing belts interchangeable with Gates PowerGrip?
Yes. D&D synchronous belts are built to standard pitch and tooth-form dimensions, so a belt of a given profile, pitch length and width interchanges with the equivalent Gates PowerGrip, Continental Synchroforce, Dayco or Bando belt. Provide the molded number and we will confirm.
How do I identify a timing belt with no markings?
Identify it from three things: tooth pitch (distance between two adjacent teeth), total tooth count, and belt width. Measure the pitch, count the teeth and measure the width, then call (888) 203-2358 and we will match it to a D&D part.
Need a timing belt cross or a quote?
Houston warehouse — same-day shipping on stock items. Tell us the size or the part number you are replacing and we will confirm the cross.
Call (888) 203-2358
