When a slow, heavy driven shaft has to be driven at 90 degrees and there is nowhere to put a foundation, the SA97 hollow shaft speed reducer is usually the answer. A 97 mm frame carries the torque; the hollow bore carries the shaft; the torque arm carries the reaction. Because the first stage is helical, the unit sustains high reduction ratios without the heating that a pure worm gearbox of the same size would suffer on continuous service.
A Large Frame That Mounts on the Shaft
The hollow output is machined concentric with the housing bore in a single setup, so the driven shaft runs true without shimming. Gears are 20CrMnTi carburised to HRC58~62 over an HRC33~40 core and ground to grade 6~5; shafts are 42CrMo. Temperature rise stays within 40 C on the housing and 50 C on the oil, and oil seals are NAK as standard with FKM available for hot or washed-down areas.
SA97 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, cementit-ing, 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 | ≤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 |
Selected application examples:
- Wastewater treatment and water supply
- Mining and bulk material handling
- Building and construction machinery
- Metal processing and forming lines
- Wood, forest and recycling equipment
Purchase Information
WGT builds the SA97 to order with transparent EXW pricing and full pre-shipment test records. Send the shaft diameter, ratio, mounting position (M1-M6) and a duty description and we confirm the selection with a drawing and a firm price - normally the same working day. Production lead time is 5-10 weeks and urgent units can be prioritised.
Model Range and Centre Distances
| Model | Centre distance | Output | Typical duty |
|---|
| SF97 | 97 mm | solid shaft, foot | thickeners, kilns |
| 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 |
| SF107 | 107 mm | solid shaft, foot | heavy material handling |
Frame numbers follow the centre distance, from 37 mm up to 107 mm. Mounting variants do not change performance: foot, hollow shaft, flange and torque-arm versions of a given frame all use identical gearing.
Proven Installations
Grain terminal elevators
A grain terminal powers its bucket elevators with SF77 gear reducers. The anti-run-back option holds the loaded buckets during power cuts, and standard interface dimensions meant the old foundations were reused as they were.
Pallet lift in a warehouse
A logistics integrator selected SA67 units for pallet lifts. The hollow output bore carries the lift screw directly, and one year of three-shift operation has passed without a single seal replacement.
![gearbox applications in quarry food and water plants]()
Conveyor, mixer, crusher and wastewater duties share the same gear family.
Selection Example: Thickener scraper in a water plant
Take an 11 kW motor at 960 rpm turning the scraper at under 12 rpm. The ratio follows directly: 960 / 12 = 80, so i=80 within one unit. In this case the helical first stage holds efficiency up where a plain worm box would cook. Motor speed over target speed gives the ratio; the driven machine decides the service factor, and the two together decide the model.
![worm gear reducer sizing procedure diagram]()
The four inputs the online selector asks for.
Tell Us the Torque, We Confirm the Model
Not sure where to start? Work out the ratio, torque and frame size yourself with the WGT Motor & Gearbox Online Selection System, then send the result - we confirm it in writing.
A photo of the nameplate, the motor power and the output speed you need are enough to start. We confirm the frame size, ratio and mounting style and return a written quotation the same day. Looking for a speed reducer for bucket elevator? Tell us the duty point and we will confirm the model in writing.
FAQ: Selection, Mounting and Maintenance
What is the service factor and how is it applied?
The service factor is a multiplier applied to your required torque to cover shocks and duty class - typically 1.0 for uniform duty, 1.25 for moderate shocks, 1.5 or more for heavy shock loads. Send us the driven machine and duty and we will apply the correct factor.
What ambient temperature range can the unit work in?
Standard units suit -10 to +40 deg C ambient with the supplied mineral oil. For lower temperatures we fill with synthetic oil; for higher ambient or frequent starting we advise the next larger frame or an oil cooler.
