Worm Gearbox / Gear Reducer
M-I Series Worm Gear Reducers
Precision Torque. Industrial Confidence.
Crafted for powerful performance in compact spaces, the M-I Series Single Reduction Worm Gear offers unrivaled reliability across 12 frame sizes, handling input power from 1/8 to 75 HP. This series is engineered for smooth torque transmission with gear ratios ranging from 7.5:1 to 100:1, making it ideal for a wide variety of industrial machinery applications.
Core Features:
🔩 Keyed hollow bore design for secure, maintenance-friendly integration
⚙️ Standard B5 & B14 motor mounts for universal compatibility
🔗 Optional plug-in output shafts (single/double) for versatile configuration
🛠️ Customizable output flanges and torque limiter to enhance safety and adaptability
Built for engineers who demand both function and form, the M-I Series delivers consistent performance, low vibration, and ease of integration — whether you’re driving automation systems, conveyors, or process equipment.
Efficiency starts with precision. The M-I Series makes it easy.
P-MI Series Gear Reducers
Compact Power. Extended Precision.
Engineered for high-torque applications, the P-MI Series combines double reduction helical-worm gearing for exceptional efficiency and compact performance. With 13 flexible size combinations and input power ratings ranging from 1/8 to 5 HP, this series ensures smooth, reliable transmission even in demanding environments.
Key features include:
🔩 Keyed hollow bore standard for secure shaft coupling
⚙️ Wide gear ratios from 75:1 to 400:1 for fine control
🔗 Standard B5/B14 motor interfaces for easy integration
🛠️ Optional output flanges and slow-speed plug-in shafts (single/double) for modular configuration
Perfect for applications requiring silent operation, higher gear ratios, and enhanced durability in a compact footprint.
Customize your drive. Trust in precision. Choose P-MI Series
C-MI Series Gearbox
Ultra-High Ratios. Compact Brilliance.
Built for precision control in space-saving designs, the C-MI Series delivers exceptional torque transfer through a double reduction compound worm gear system. Offered in 14 size combinations with input power ratings from 1/8 to 10 HP, this powerhouse is ideal for high-ratio, low-speed applications in demanding industries.
Key Features:
⚙️ Double reduction gearing for enhanced output torque and fine speed control
🔩 Keyed hollow bore standard for secure, hassle-free integration
🧮 Extra-wide ratio range: 225:1 to 8,000:1
🔗 Standard B5/B14 motor compatibility ensures plug-and-play efficiency
🛠️ Optional output flanges & slow-speed plug-in shafts (single/double) for configuration flexibility
⛓️ Torque limiter option adds safety and protection for overload conditions
Whether you’re powering precision conveyors or compact automation setups, the C-MI Series delivers unmatched control, durability, and adaptability in even the tightest mechanical spaces.
Precision. Modularity. Confidence. That’s the C-MI Series difference.
MU Series – Single Reduction Worm Gear Units
The MU Series offers compact and efficient single reduction worm gear units, engineered for a wide range of industrial applications. Available in 7 frame sizes, the series supports input power ratings from 1/8 HP to 25 HP.
Key Features:
Gear Ratios: From 7.5:1 to 100:1
Input Compatibility: Designed for use with standard B5 or B14 flange-mounted motors
Output Configuration:
Standard: Keyed hollow bore
Optional: Output flanges, plug-in output shafts (single or double), and torque limiter
These gear units provide smooth, quiet operation and are well-suited for machinery requiring moderate speed reduction and high torque in a compact footprint.
P-MU Series – Double Reduction Helical-Worm Gear Units
The P-MU Series features robust double reduction gear units combining helical and worm gearing for enhanced torque transmission and efficiency. Available in 15 size combinations, these units are designed for a wide range of low-speed, high-torque applications.
Key Features:
Gear Ratios: Wide range from 75:1 to 400:1
Input Power: Supports 1/8 HP to 5 HP
Input Interface: Compatible with standard B5 or B14 flange-mounted motors
Output Configuration:
Standard: Keyed hollow bore
Optional: Output flanges, plug-in output shafts (single or double)
With compact dimensions and versatile mounting options, the P-MU Series is ideal for demanding applications where space efficiency and torque output are critical.
C-MU Series – Double Reduction Compound Worm Gearbox
The C-MU Series is a high-ratio, double reduction compound worm gearbox designed for applications requiring precise speed reduction and high torque in a compact form. Available in 6 size combinations, it is ideal for low-speed, high-torque operations.
Key Features:
Gear Ratios: Ultra-high reduction ratios from 225:1 to 8,000:1
Input Power: Supports 1/8 HP to 2 HP
Input Compatibility: Fits standard B5 or B14 flange-mounted motors
Output Configuration:
Standard: Keyed hollow bore
Optional: Output flanges, plug-in output
shaft (single or double), and torque limiter
Compact, efficient, and reliable, the C-MU Series is suited for specialized machinery and automation systems that demand extreme reduction in speed with smooth and quiet operation.
SITI metric worm gear units are available in 12 sizes and are built of pressure die-cast aluminum and cast iron. They are interchangeable with most European brands and are available with multiple bolt-on components to customize for your application, including; helical input, double worm combinations, multiple output flanges per size, torque arm, shaft covers, and single & double output shafts.
| Series | Model | Downloads |
|---|---|---|
| Worm Gearbox | Worm Gear Flyer | |
| Worm Gearbox | Worm Gear Complete Catalog | |
| Worm Gearbox | Worm Gear Manual | |
| MI Series | MI Worm Gear 60Hz Ratings | |
| MI Series | MI Worm Gear Interchanges | |
| MI Series | MI Worm Gear Spare Parts | |
| MU Series | MU Worm Gear 60Hz Ratings | |
| MU Series | MU by Power | |
| MU Series | MU Worm Gear Accessories | |
| MU Series | MU 40 | |
| MU Series | MU 50 | |
| MU Series | MU 63 | |
| MU Series | MU 75 | |
| MU Series | MU 90 | |
| MU Series | MU 110 |
