Trapezoidal Timing Belts (MXL, XL, L, H, XH, XXH)
Trapezoidal timing belts are the original synchronous belt design, featuring straight-sided teeth with an angled (trapezoidal) profile that meshes with matching pulley grooves for positive, no-slip power transmission. The trapezoidal tooth form is the ANSI/RMA standard used on the majority of industrial equipment manufactured in North America. Texas Belting stocks trapezoidal timing belts in six standard pitches, from miniature MXL drives to extreme heavy-duty XXH applications.
The trapezoidal profile family covers a wider range of load capacities than any other single tooth form, spanning from precision instruments and encoders (MXL) to mining equipment and heavy presses (XXH). All trapezoidal belts are constructed with neoprene (rubber) bodies, fiberglass tensile cords, and nylon tooth facing as standard. Urethane versions with steel or Kevlar cord are available for MXL, XL, L, and H pitches.
Tooth form: Trapezoidal (straight-sided, angled)
Standard: ANSI/RMA (North American)
Pitches: MXL (0.080"), XL (0.200"), L (3/8"), H (1/2"), XH (7/8"), XXH (1-1/4")
Standard material: Neoprene with fiberglass cord, nylon tooth facing
Also available: Urethane with steel/Kevlar cord (MXL, XL, L, H); HNBR specialty compounds (XH, XXH)
Trapezoidal Pitch Comparison
The six ANSI/RMA trapezoidal pitches cover the full range from miniature to extreme heavy-duty. Each pitch has a dedicated page with detailed specifications, part number decoders, width guides, and FAQs.
| Profile | Pitch | Pitch (mm) | Load Class | Common Width Range | Typical Applications |
|---|---|---|---|---|---|
| MXL | 0.080" | 2.032mm | Very light | 1/8" to 1/2" | Instruments, encoders, office equipment, 3D printers |
| XL | 0.200" (1/5") | 5.08mm | Light to moderate | 1/4" to 1" | Small machinery, robotics, general industrial, light automation |
| L | 3/8" | 9.525mm | Moderate to heavy | 1/2" to 2" | General industrial, packaging, compressors, pumps, fans |
| H | 1/2" | 12.7mm | Heavy | 3/4" to 3" | Heavy industrial, machine tools, large compressors, conveyors |
| XH | 7/8" | 22.225mm | Very heavy | 1" to 4" | High-torque conveyors, presses, extruders, machine tools |
| XXH | 1-1/4" | 31.75mm | Extreme | 2" to 5" | Mining, steel processing, heavy presses, bulk material handling |
What Makes Trapezoidal Belts Different?
Trapezoidal timing belts were the first generation of synchronous belt design, introduced in the 1940s. The straight-sided tooth form provides reliable positive engagement at a lower manufacturing cost than newer curvilinear profiles. Understanding the trapezoidal tooth form helps buyers make informed decisions about when to specify trapezoidal versus newer profiles like HTD or GT.
Trapezoidal Tooth Form
The trapezoidal tooth has flat, angled sides that form a trapezoid shape. When the belt meshes with the pulley, the tooth enters the groove from the top and contacts the groove walls along the flat sides. This engagement pattern is simple and effective but concentrates stress at the tooth root corners, which limits the maximum load per tooth compared to curvilinear designs.
Trapezoidal vs. Curvilinear (HTD/GT)
Curvilinear profiles like HTD and GT use a rounded tooth form that distributes stress more evenly across the tooth surface. This allows curvilinear belts to carry higher loads per tooth and resist tooth shear better than trapezoidal belts at equivalent pitch. However, trapezoidal belts remain the dominant installed base in North America and are the correct replacement for any equipment originally designed with trapezoidal pulleys.
| Factor | Trapezoidal (MXL/XL/L/H/XH/XXH) | Curvilinear (HTD / GT) |
|---|---|---|
| Tooth shape | Straight-sided, angled (trapezoid) | Rounded, semi-circular or modified curve |
| Stress distribution | Concentrated at tooth root corners | Distributed evenly across tooth surface |
| Load capacity per tooth | Standard | Higher (20-40% more at equivalent pitch) |
| Tooth shear resistance | Good | Better |
| Standard system | ANSI/RMA (North American) | HTD: RMA/ISO (global). GT: Gates proprietary. |
| Installed base | Very large (decades of North American equipment) | Growing (newer equipment, upgrades) |
| When to choose | Replacing existing trapezoidal. Matching installed pulleys. | New designs. Upgrades for higher load. Chain replacement. |
For a detailed visual comparison of all tooth profiles, see the Timing Belt Tooth Profiles Explained guide. For help deciding between trapezoidal and curvilinear for a new design, see the Timing Belt Selection Guide.
Part Number Format for Trapezoidal Belts
All ANSI trapezoidal timing belts follow the same part number convention: pitch length in tenths of an inch, followed by the profile code, followed by the width in hundredths of an inch.
| Example Part Number | Profile | Pitch Length | Width |
|---|---|---|---|
| 54.4-MXL-025 | MXL | 5.44" | 1/4" (0.25") |
| 130XL037 | XL | 13.0" | 3/8" (0.375") |
| 225L075 | L | 22.5" | 3/4" (0.75") |
| 450H200 | H | 45.0" | 2" (2.00") |
| 630XH300 | XH | 63.0" | 3" (3.00") |
| 800XXH400 | XXH | 80.0" | 4" (4.00") |
For detailed part number decoding for each pitch, visit the individual pitch pages linked above. Texas Belting can cross-reference trapezoidal part numbers from Gates, Continental, Bando, Diesel Belting, Megadyne, and other manufacturers. Call 888-203-2358 or send us your part number. See our Pitch Chart for a complete reference of all pitches and formats.
Materials and Construction
Neoprene (Standard)
Standard trapezoidal timing belts are constructed with a neoprene (chloroprene rubber) body, fiberglass tensile cords, and nylon tooth facing. This construction provides good oil resistance, heat resistance, and long service life in general industrial environments. Neoprene trapezoidal belts are available in all six pitches (MXL through XXH) and are the default replacement for existing equipment.
Urethane (Specialty)
Urethane (polyurethane) trapezoidal belts with steel or Kevlar cord are available in MXL, XL, L, and H pitches. Urethane provides superior chemical resistance, abrasion resistance, and low particulate generation for cleanroom, food-contact, and precision applications. Urethane trapezoidal belts are also available in open-end (continuous roll) form.
HNBR and Specialty Compounds
For XH and XXH pitches, HNBR (Hydrogenated Nitrile Butadiene Rubber) and other specialty compounds are available for elevated temperature, chemical exposure, or extended service life requirements. Contact Texas Belting for specialty compound availability.
Trapezoidal Timing Belt Brands We Carry
| Brand | Trapezoidal Products | Notes |
|---|---|---|
| Gates | PowerGrip MXL, XL, L, H, XH, XXH | Industry standard. Full range of trapezoidal pitches. |
| Continental / ContiTech | Synchroforce, Synchrobelt trapezoidal | OEM and industrial replacement. All pitches. |
| Bando | Bando MXL, XL, L, H, XH, XXH | High-quality Japanese manufacturing. Strong OEM presence. |
| Diesel Belting | Diesel trapezoidal, all pitches | Cost-effective replacement for all standard trapezoidal sizes. |
| Megadyne | Megapower trapezoidal | European manufacturing. Neoprene and urethane options. |
Trapezoidal Timing Belt FAQs
Need Trapezoidal Timing Belts?
Tell us the pitch, part number, or application details. We stock all six trapezoidal pitches for fast shipping from Houston.
