The R137 large inline helical gear reducer fills the gap between the mid R frames and the top of the range. Its 137 mm centre distance and deep housing section give it the torque reserve that heavy mill and hoist drives need, while the all-helical train keeps the speed reducer on the machine axis - no bevel stage, no sideways motor overhang, and efficiency that stays near 96% regardless of ratio.
Sizing up the R137
What separates the R137 from smaller inline frames is not the gearing but the structure around it. The housing walls are thicker and heavily ribbed, the output shaft is cut from 42CrMo and tempered to HRC25~30, and the bearing positions are bored in a single setup so the shaft runs true even at full torque. Gears are 20CrMnTi, carburised to HRC58~62 over a HRC33~40 core and ground to grade 6~5, which is why backlash stays within 20 arcmin on reversing duties.
R137 Specification Table
| 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 |
Main fields of application:
- Paper, textile and light industry
- Cranes, hoists and winches
- Wastewater treatment and water supply
- Food processing and packaging lines
- Belt, screw and chain conveyors
Quotation and Dispatch
Frames of this size are quoted against the real duty point: motor power, driven-machine torque, daily running hours and the mounting position (M1-M6). Send those four items - or a photo of the old nameplate - and WGT returns a confirmed selection with a dimension drawing and a firm factory price, normally inside one working day. Every R137 ships in a reinforced export crate from NINGBO or SHANGHAI with a one-year warranty and pre-shipment test records for noise, temperature rise and backlash.
Selection Example: Ball-mill auxiliary drive
Take a 30 kW motor at 980 rpm turning a ball-mill auxiliary drive at 11 rpm. The ratio follows directly: 980 / 11 = 89, so i=90 is selected. In this case the 137 mm frame and ground gearing absorb the shock of mill start-up. 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.
![gear reducer selection flow chart - ratio and frame size]()
Figure: from motor data to a confirmed gearbox model in four steps.
Common Models in the R Series
| Model | Centre distance | Output | Typical duty |
|---|
| R137 | 137 mm | solid shaft, foot | mill drives, large hoists |
| R17 | 17 mm | solid shaft, foot | small conveyors, dosing screws |
| R27 | 27 mm | solid shaft, foot | packaging, light agitators |
| R37 | 37 mm | solid shaft, foot | belt conveyors, small mixers |
| 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 |
| R147 | 147 mm | solid shaft, foot | mill drives, heavy hoists |
| R167 | 167 mm | solid shaft, foot | heaviest inline drives |
The table below lists the foot-mounted R frames; naming makes selection easy: R = foot-mounted solid shaft, RF = flange-mounted, RS and RFS = shaft and flange combinations - all sharing the same gear set, ratio and centre distance as the R foot model.
Application Cases
Cold-store conveyor
A cold-store operator uses reducers on freezer-room conveyors. Low-temperature synthetic oil and moisture-resistant seals keep the units running below -20 deg C ambient.
Bakery spiral cooler
A bakery equipment builder fits units to spiral cooler drives. The compact right-angle layout fits under the spiral cage, and food-grade lubrication was specified for the hygienic area.
![industrial gearbox applications - conveyor mixer crusher wastewater]()
Figure: typical industries that use the WGT S-series gear reducers.
Frequently Asked Questions
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.
What warranty and documentation come with the gearbox?
A one-year warranty covers material and workmanship. Each unit ships with a test record (noise, temperature rise, backlash), a dimension drawing and an installation manual.
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.
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 steel mill? Tell us the duty point and we will confirm the model in writing.
