When a drive needs more muscle than the small S frames can offer, the S87 helical worm speed reducer steps in: 87 mm centre distance, robust 42CrMo shafts and a housing section designed for continuous load. The unit follows the standard interface dimensions of the S87 frame family and is widely used on screw conveyors, industrial washers, agitators and water-treatment scrapers.
Heavy Duty in a Compact Frame
Rolling contact in the helical stage keeps losses low and heat generation modest, which is what lets the S87 run long shifts without an oil cooler. Surface hardness reaches HRC58~62 over a ductile HRC33~40 core, and the maximum temperature rise is 40 C on the housing and 50 C on the oil, both verified during factory run-in.
S87 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 |
Duties this frame size is regularly chosen for:
- Wood, forest and recycling equipment
- Mining and bulk material handling
- Metal processing and forming lines
- Car-washing and car-park systems
- Textile, leather and paper industry
Ordering, Tests and Warranty
Specify ratio, output speed, mounting position (M1-M6) and shaft direction; WGT returns a selection confirmation with torque limits and a firm price. Sampling units for OEM validation are welcome. Production lead time is normally 5-10 weeks with sea or air freight from NINGBO / SHANGHAI, and every S87 gear reducer carries a one-year warranty and lifetime technical support.
Selection Example: River-sand screw washer
Take a 7.5 kW motor at 1440 rpm turning the washer screw at 24 rpm. The ratio follows directly: 1440 / 24 = 60, ratio i=60. In this case the 87 mm frame takes the shock of a slug of wet sand without stalling. Work through the same three steps - speed, output speed, torque - and the model number falls out; we verify it against the duty class before quoting.
![gear reducer ratio calculation steps]()
From duty point to model number - the same four steps every time.
Applications in Industry
Steel mill run-out table
On the run-out table of a small steel mill, SF107 units handle the repeated starts and stops of hot billet handling. The 42CrMo output shafts tolerate the thermal cycling, and torque-arm mounting keeps the drive clear of the roller frames.
Cement plant clinker belt
A cement plant drives its clinker transport belt with SF97 reducers in dusty, high-ambient conditions. Sealed housings and a 40 deg C maximum temperature rise let the units sit close to the kiln without extra cooling.
![gear reducer industries served - WGT]()
Industry map: the sectors where the S series is most common.
Buyer Questions and Answers
Do you offer food-grade or washdown versions?
We can supply food-grade lubricant, FKM (Viton) oil seals and stainless fasteners for washdown areas. These units are common in bakeries, dairies and packaging halls where hygiene and moisture are daily concerns.
What noise level can I expect from the S series?
Measured noise is 60 to 68 dB depending on size and ratio, verified on the test bench. The helical first stage is what keeps the sound level low; a single-stage worm unit of the same ratio would be noticeably louder.
S Series Model Overview
| Model | Centre distance | Output | Typical duty |
|---|
| S87 | 87 mm | solid shaft, foot | screw conveyors, washers |
| S37 | 37 mm | solid shaft, foot | dosing screws, small conveyors |
| S47 | 47 mm | solid shaft, foot | packaging, small mixers |
| S57 | 57 mm | solid shaft, foot | bagging belts, stirrers |
| S67 | 67 mm | solid shaft, foot | paddle mixers, feeders |
| S77 | 77 mm | solid shaft, foot | turntables, elevators |
| S97 | 97 mm | solid shaft, foot | thickeners, heavy conveyors |
The series is sized by centre distance rather than by motor power, so one frame can serve several motor sizes and ratios. The S / SA / SF / SAF suffixes describe shaft and mounting, not capacity.
Fast Quotation for OEM and Repeat Orders
Buying one unit or one hundred? Run your duty point through the WGT Motor & Gearbox Online Selection System first: it saves a round of emails and gets you to a firm price faster.
Single units ship on the same production route as batch orders, with no minimum-order surcharge. For OEM programmes we hold framework pricing and reserve capacity for your scheduled call-offs. Looking for a gear reducer for food processing machine? Tell us the duty point and we will confirm the model in writing.
