Buyers who want a dependable mid-small inline gear unit usually arrive at the R37 sooner or later. The 37 mm centre distance follows the common industry dimension, so existing foundations, couplings and guards stay where they are, and because every stage is helical the speed reducer runs cooler and quieter than a worm unit of the same ratio - efficiency stays in the 94~96% band instead of falling away as the ratio rises.
Why the R37 Runs Cool and Quiet
Rolling contact between helical teeth keeps friction low, so heat build-up is modest: the maximum housing rise is 40 C and the oil rise 50 C, measured in factory run-in tests. The housing is a single casting in cast iron or ductile iron at HBS190-240, bored in one setup for true shaft alignment; gears are 20CrMnTi, case-carburised to HRC58~62 over a tough HRC33~40 core and finished by precision grinding to grade 6~5.
Ratings at a Glance
| 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, carburising, quenching, etc. |
| Efficiency | 94%~96% (depends on the transmission stage) |
| Noise (max) | 60~68 dB |
| Temp. rise (max) | 40 C |
| Temp. rise (oil) (max) | 50 C |
| Vibration | ≤20 µm |
| 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 |
Typical duty points where this unit is specified:
- Mixers, agitators and kneaders
- Wastewater treatment and water supply
- Food processing and packaging lines
- Cement, lime and aggregate plants
- Cranes, hoists and winches
Quotation and Delivery Terms
Every R37 ships factory-tested with noise, temperature rise and backlash recorded before packing in a standard export wooden crate. Send your ratio, output speed and mounting style - our engineers confirm the selection the same day and quote EXW or CIF accordingly. Urgent units for a breakdown can be air-freighted after payment, and spare seal and bearing kits are available from stock.
The R Series at a Glance
| Model | Centre distance | Output | Typical duty |
|---|
| R37 | 37 mm | solid shaft, foot | belt conveyors, small mixers |
| R17 | 17 mm | solid shaft, foot | small conveyors, dosing screws |
| R27 | 27 mm | solid shaft, foot | packaging, light agitators |
| R47 | 47 mm | solid shaft, foot | screw conveyors, feeders |
| R57 | 57 mm | solid shaft, foot | mixers, aeration blowers |
| R67 | 67 mm | solid shaft, foot | mixers, extruders |
| R77 | 77 mm | solid shaft, foot | extruders, heavy conveyors |
| R87 | 87 mm | solid shaft, foot | screw conveyors, agitators |
| R97 | 97 mm | solid shaft, foot | thickeners, blowers |
| R107 | 107 mm | solid shaft, foot | aerators, heavy conveyors |
| R137 | 137 mm | solid shaft, foot | mill drives, large hoists |
| R147 | 147 mm | solid shaft, foot | mill drives, heavy hoists |
| R167 | 167 mm | solid shaft, foot | heaviest inline drives |
All frames share one helical gear set family, so a change of frame size rarely means a change of mounting: R is the foot-mounted version with a solid shaft, RF adds a flange, and RS / RFS cover shaft-mounted and flange-mounted duties.
Selection Example: Feed-mill screw conveyor
Take a 3 kW motor at 1450 rpm driving a screw conveyor at 29 rpm. The ratio follows directly: 1450 / 29 = 50, i=50. In this case the coaxial layout lets the drive sit directly under the conveyor trough. That single division gives the catalogue ratio; the service factor for your duty class is then applied to the torque, and the frame size follows.
![how to size a helical gearbox in four steps]()
Sizing flow: motor speed, target output speed, torque, service factor.
Where This Series Works in Practice
Automatic car-wash line
A car-wash equipment builder fits hollow-shaft reducers to its conveyor chains. The compact frame hides inside the wash tunnel, and FKM seal options handle the constant moisture.
Textile dyeing drums
A dyeing machine maker uses 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.
Technical Questions, Answered
How do I calculate the ratio I need?
Divide motor speed by the target output speed (i = n1/n2), then check the required torque against the rating table with your service factor. The online selector below does this automatically.
Can the reducer be supplied with a brake motor or an IEC motor flange?
Yes. We supply the reducer as a bare unit with an IEC standard input flange, and you can bolt on any IEC or NEMA motor - including a brake motor. The flange dimensions follow the common IEC pattern, so existing motors drop straight on.
![helical gear reducer application fields]()
Common application areas for right-angle helical drives.
Size It, Quote It, Ship It
One minute, one model. Skip the back-and-forth: configure your drive in the WGT Motor & Gearbox Online Selection System and send us the result for a same-day quotation.
Give us the driven machine, the required output speed and the daily running hours, and we return a confirmed model number with torque margin and a firm price - no obligation, no charge for the selection work. Looking for a gear reducer for screw conveyor? Tell us the duty point and we will confirm the model in writing.
