The SF37 helical worm gear reducer is the most compact unit of the SF series - a foot-mounted speed reducer gearbox that pairs a helical input stage with a worm output stage. This two-stage layout gives buyers a practical compromise: higher efficiency than a pure worm drive, yet quieter and more economical than a full helical bevel unit. The SF37 follows the standard interface dimensions of its frame family, so it suits the existing assembly footprint for hassle-free mounting.
Key Features of the SF37 Gear Reducer
- Two-stage helical + worm transmission, smooth running and self-locking option on the output
- Rigid cast-iron housing, HBS190-240, machined in one setup for true shaft alignment
- Case-hardened 20CrMnTi gears, ground to grade 6~5 for low noise (60~68 dB)
- Transmission efficiency 94%~96% - noticeably better than single-stage worm units of the same size
- Standard IEC motor flange or solid output shaft; torque arm and foot options available
Technical Data
| Housing material | Cast iron/Ductile iron |
| Housing hardness | HBS190-240 |
| Gear material | 20CrMnTi alloy steel |
| Surface hardness of gears | HRC58~62 |
| Gear core hardness | HRC33~40 |
| Input / Output shaft material | 42CrMo alloy steel |
| Input / Output shaft hardness | HRC25~30 |
| Machining precision of gears | precision grinding, grade 6~5 (ISO 1328) |
| Lubricating oil | GB L-CKC220~460 / Shell Omala 220~460 |
| Heat treatment | tempering, cementit-ing, quenching, etc. |
| Efficiency | 94%~96% (depends on the transmission stage) |
| Noise (max) | 60~ 68dB |
| Temp. rise (max) | 40°C |
| Temp. rise (oil) (max) | 5 0°C |
| Vibration | ≤20μm |
| Backlash | ≤20Arcmin |
| Brand of bearings | HRB/LYC/ZWZ/C&U (SKF, FAG, INA, NSK optional) |
| Brand of oil seal | NAK -- Taiwan or other brands requested |
Main fields of application:
- Chemical and environmental protection plants
- Metal processing lines
- Building and construction machinery
- Agriculture and food processing
- Textile, leather and paper industry
Why Source the SF37 from WGT?
WGT builds the SF37 gear reducer on the same tooling as the standard production line: every housing and gear set is inspected against the frame drawings, and units ship with a one-year warranty. Whether you need one urgent unit for emergency maintenance or a batch of several hundred for OEM equipment, we reply with a firm quotation and delivery date within 24 hours. Request the SF37 price list or a CAD drawing via the inquiry button - samples for performance testing are also available.
Selection Example: Dosing pump drive
Take a 1.5 kW four-pole motor (1440 rpm) feeding a dosing pump that must turn at 48 rpm. The ratio follows directly: 1440 / 48 = 30, so a ratio near i=30 is selected. In this case the small 37 mm frame keeps the dosing skid compact. The same three numbers - motor speed, target output speed, required torque - are all you need; our engineers (or the online selector below) cross-check the service factor for your duty cycle.
![how to size a gear reducer in 4 steps - gearbox selection flow]()
Common Models in the SF Series
| Model | Centre distance | Output | Typical duty |
|---|
| SF37 | 37 mm | solid shaft, foot | small conveyors, dosing |
| SF47 | 47 mm | solid shaft, foot | packaging, dosing pumps |
| SF57 | 57 mm | solid shaft, foot | belt conveyors, stirrers |
| SF67 | 67 mm | solid shaft, foot | mixers, feeders |
| SF77 | 77 mm | solid shaft, foot | turntables, elevators |
| SF87 | 87 mm | solid shaft, foot | screw conveyors, washers |
| SF97 | 97 mm | solid shaft, foot | thickeners, kilns |
| SF107 | 107 mm | solid shaft, foot | heavy material handling |
The table below lists the eight foot-mounted frames;
Naming makes selection easy: S = solid shaft, SA = hollow shaft, SAF = hollow shaft with flange, SAZ = torque-arm version - all sharing the same gear set and centre distance as the SF foot model.
Application Cases
Wastewater treatment plant
A municipal wastewater plant replaced twelve ageing agitator drives with SA-series helical worm units. Sealed housings and NAK oil seals stood up to the humid atmosphere, and the hollow-shaft mounting let the maintenance crew swap units without touching the mixer shafts.
Textile dyeing lines
A dyeing machine maker uses SF67 speed reducers on its fabric-turning drums. Low vibration (under 20 microns) prevents streaks in the fabric, and the 94-96% efficiency keeps the heat load down in a warm workshop.
![industrial gearbox applications - conveyor mixer crusher wastewater]()
Frequently Asked Questions
How efficient is a helical worm gear reducer?
The two-stage design reaches 94%~96% efficiency depending on the transmission stage - well above a single-stage worm unit, because the helical input stage handles the first reduction with less sliding loss.
Which lubricating oil should be used?
GB L-CKC220~460 or Shell Omala 220~460 as supplied. Under normal duty the housing is lubricated for life; in hot or continuous-duty environments an oil change after the first 400 hours and then every 4000 hours is recommended.
Get Your Drawing and Quotation within 24 Hours
Ready to size your drive? Not sure which model fits? Try our online WGT Motor & Gearbox Online Selection System to match motor power, ratio and mounting in one minute.
Or simply send your motor data (kW, speed, duty) and driven-machine details through the inquiry button - we reply with a completed datasheet, dimension drawing and factory price the same working day. Looking for a gearbox for belt conveyor? Tell us the duty point and we will confirm the model in writing.
