GT / GT2 / GT3 Timing Belt Sprockets
Profile: GT (Gates Tooth) modified curvilinear
Generations: GT (original), GT2 (second gen), GT3 (current, highest performance)
Pitches: 2M (2mm), 3M (3mm), 5M (5mm), 8M (8mm)
Mounting: Pilot bore, QD bushing, Taper Lock bushing, clamp hub
Materials: Aluminum (small sizes), steel, cast iron
Brands: Gates (PowerGrip GT3)
In Stock: Same-day shipping from Houston
GT sprockets use a modified curvilinear tooth profile developed by Gates to deliver higher load capacity, lower noise, and longer belt life than standard HTD sprockets at the same pitch. The GT tooth shape distributes load more evenly across the tooth face rather than concentrating stress at the tooth root, which means a GT drive can transmit more torque at the same belt width or use a narrower belt for the same load.
The GT profile has evolved through three generations. GT (original) and GT2 (second generation) are still found on existing equipment, but GT3 is the current standard for all new installations. GT3 sprockets are backward compatible with GT2 belts in most applications, but are not compatible with HTD belts. Texas Belting stocks Gates PowerGrip GT3 sprockets and matching GT timing belts so you can source confirmed-compatible drive sets from a single supplier.
GT Generations Explained
| Generation | Details |
|---|---|
| GT (Original) | First Gates modified curvilinear profile. Improvement over HTD in load distribution. Found on older equipment. Being phased out in favor of GT3. |
| GT2 | Second generation. Further optimized tooth shape. Better engagement and quieter operation than original GT. Still widely installed. |
| GT3 (Current) | The current Gates standard. Highest load capacity, lowest noise, longest belt life of all GT generations. Backward compatible with GT2 belts in most applications. All new GT installations should use GT3 sprockets. |
GT Sprockets by Pitch
| Pitch | Details |
|---|---|
| 2M | Pitch: 2mm. Load: Very light. Tooth counts: 12 to 60. Belt widths: 3mm, 6mm, 9mm. Mount: Pilot bore or clamp. Use: Miniature drives, small robotics, 3D printers, encoders, precision instruments. Aluminum sprockets. Smallest GT pitch. |
| 3M | Pitch: 3mm. Load: Light. Tooth counts: 12 to 72. Belt widths: 6mm, 9mm, 15mm. Mount: Pilot bore or set screw. Use: Small OEM, office equipment, light automation, stepper motor drives. Aluminum or steel. |
| 5M | Pitch: 5mm. Load: Medium to heavy. Tooth counts: 14 to 72+. Belt widths: 9mm, 15mm, 25mm. Mount: Pilot bore, QD, or Taper Lock. Use: The most common industrial GT pitch. Servo motors, packaging, conveyors, precision positioning. Steel or aluminum. |
| 8M (8MGT) | Pitch: 8mm. Load: Heavy. Tooth counts: 18 to 112+. Belt widths: 20mm, 30mm, 50mm, 85mm. Mount: Pilot bore, QD, or Taper Lock. Use: High-torque industrial drives, large conveyors, machine tools, heavy packaging. Steel or cast iron. Often labeled "8MGT" on belt and sprocket. |
GT vs. HTD: Key Differences
GT and HTD sprockets share the same pitch sizes (3M, 5M, 8M) but use different tooth shapes. This is the most common source of profile confusion in timing belt drives.
| Feature | Details |
|---|---|
| GT Tooth | Modified curvilinear (Gates patented). Load distributed across the full tooth face. Higher capacity per tooth than HTD. |
| HTD Tooth | Fully semicircular. Load concentrated at the tooth root. Lower capacity per tooth than GT at the same pitch. |
| Load Capacity | GT carries approximately 30% more load than HTD at the same pitch and belt width. This means GT drives can use narrower belts for the same application, saving space and weight. |
| Noise | GT runs quieter than HTD due to better tooth engagement geometry. |
| Compatibility | Not interchangeable. GT belts require GT sprockets. HTD belts require HTD sprockets. Mixing causes premature failure. |
| Availability | GT is a Gates proprietary profile. HTD is an open standard available from multiple manufacturers. GT is primarily sourced through Gates or authorized distributors. |
Mounting Options
| Mount Type | Details |
|---|---|
| Pilot Bore | Rough-bored hub, finish-machined to shaft size. Set screw and keyway. Common on 2M, 3M, and smaller 5M sprockets. Low cost. |
| Clamp Hub | Split clamp collar with clamping screws. No keyway needed. Common on 2M and 3M for stepper/servo motor shafts. High concentricity. |
| QD Bushing | Removable tapered bushing. Fast install/removal. One sprocket fits many shaft sizes. Standard on medium to large 5M and 8M sprockets. |
| Taper Lock | Split tapered bushing. High concentricity and torque capacity. Stainless option for food/pharma. Available on 5M and 8M sprockets. |
GT Sprocket Part Number Decoder
Gates GT3 sprocket part numbers follow a specific format. Other manufacturers may vary, but the Gates convention is the most widely referenced.
| Example | What It Means |
|---|---|
| 2MR-20S-6 | 2M GT3 profile, 20 teeth, 6mm belt width. Pilot bore or clamp. |
| 3MR-24S-9 | 3M GT3 profile, 24 teeth, 9mm belt width. Pilot bore. |
| 5MX-36S-15 | 5M GT3 profile, 36 teeth, 15mm belt width. Pilot bore. |
| 5MX-36S-25 | 5M GT3 profile, 36 teeth, 25mm belt width. Pilot bore or QD. |
| 8MX-36S-21 | 8M GT3 profile, 36 teeth, 21mm belt width. Pilot bore. |
| 8MX-48S-36 | 8M GT3 profile, 48 teeth, 36mm belt width. QD or Taper Lock. |
The "MR" suffix is used for 2M and 3M GT3 sprockets. The "MX" suffix is used for 5M and 8M GT3 sprockets. If you have a part number you cannot decode, send it to us and we will identify the sprocket.
Why GT for Precision Drives
GT sprockets are the preferred choice over HTD for applications requiring precise positioning, low backlash, and high repeatability. The modified tooth shape provides tighter mesh between belt and sprocket, which reduces angular backlash (the amount the driven shaft can rotate when the driving shaft is held fixed). This matters in servo motor drives, CNC axes, pick-and-place machines, and any application where positional accuracy is critical.
GT3 drives also run quieter than HTD at the same speed, which is important in printing, medical equipment, and laboratory instrumentation where noise levels matter.
Common Applications
| Application | Typical GT Sprocket |
|---|---|
| Servo motor drives | 3M or 5M GT3. Pilot bore or clamp hub. Tight backlash and high repeatability. |
| Packaging machines | 5M or 8M GT3. Pilot bore or QD. Indexing, registration, and feed drives. |
| Printing/converting | 5M GT3. Pilot bore. Precise web control and roller registration. |
| CNC machine tools | 5M or 8M GT3. Spindle drives and axis motion where precision and torque both matter. |
| Robotics/automation | 2M or 3M GT3. Clamp hub or pilot bore. Small actuators, pick-and-place, gantry systems. |
| 3D printers | 2M GT2 or GT3. Clamp hub. X/Y axis drives. Very light loads, high precision. |
| Heavy conveyors | 8M GT3. QD or Taper Lock. High-torque drives where GT capacity advantage over HTD justifies the cost. |
| Medical equipment | 2M or 3M GT3. Low noise, high precision. Lab automation, imaging, dispensing. |
Brands We Carry
| Brand | Products |
|---|---|
| Gates | PowerGrip GT3 sprockets in 2M, 3M, 5M, and 8M. Pilot bore, clamp hub, QD, and Taper Lock. The GT profile is a Gates proprietary design. Gates is the primary source for GT sprockets. |
Since GT is a Gates proprietary profile, cross-referencing is limited to other Gates-authorized part numbers. If you have a GT sprocket part number from any source, send it to us and we will confirm availability.
Related Pages
Frequently Asked Questions
What does GT stand for on a timing belt sprocket?
GT stands for Gates Tooth. It is a modified curvilinear tooth profile developed and patented by Gates. The GT design distributes load more evenly across the tooth face than the standard HTD semicircular profile, resulting in higher load capacity, lower noise, and longer belt life at the same pitch size.
What is the difference between GT, GT2, and GT3?
GT, GT2, and GT3 are three generations of the Gates modified curvilinear profile. Each generation improved the tooth shape for better performance. GT3 is the current standard and offers the highest load capacity, lowest noise, and longest belt life. GT3 sprockets are backward compatible with GT2 belts in most applications. For new installations, always use GT3 sprockets and GT3 belts.
Can I use a GT sprocket with an HTD belt?
No. GT and HTD have different tooth shapes despite sharing the same pitch sizes (3M, 5M, 8M). Running an HTD belt on a GT sprocket causes accelerated tooth wear, noise, and eventual drive failure. Always match the exact profile: GT belts on GT sprockets, HTD belts on HTD sprockets. Check the belt marking carefully. See our Tooth Profiles guide for a visual comparison.
Why choose GT over HTD?
GT carries approximately 30% more load than HTD at the same pitch and belt width. GT also runs quieter and provides tighter tooth engagement for lower backlash, which matters in servo, CNC, and precision positioning applications. The trade-off is that GT is a Gates proprietary profile with more limited sourcing options than the open-standard HTD.
What does 8MGT mean on a belt or sprocket?
8MGT means an 8mm pitch GT-profile belt or sprocket. The "8M" indicates the pitch (8mm) and the "GT" indicates it uses the Gates modified curvilinear tooth profile rather than the standard HTD semicircular profile. An 8MGT sprocket is not interchangeable with a standard HTD 8M sprocket.
Can I upgrade from GT2 to GT3 sprockets?
Yes. GT3 sprockets are backward compatible with GT2 belts in most applications. This means you can install GT3 sprockets on an existing GT2 drive for an immediate performance improvement. When the GT2 belt is due for replacement, switch to a GT3 belt for full system optimization. This phased upgrade approach minimizes downtime and cost.
Are GT sprockets available with QD or Taper Lock mounting?
Yes. Larger 5M and 8M GT3 sprockets are available with QD bushing and Taper Lock mounting. Smaller 2M and 3M sprockets typically use pilot bore or clamp hub mounting. The mounting type is specified in the sprocket part number or product listing.
Can I buy matched GT belt and sprocket sets?
Yes. Tell us the pitch, tooth count, belt width, and shaft bore sizes, and we will quote a complete drive package including GT belt, GT3 sprockets, and bushings. Request a drive package quote or call 888-203-2358.
