Machine designers choose the SA47 hollow shaft worm gearbox when there is no room for a coupling and no budget for a separate bearing housing. The hollow output swallows the machine shaft, the torque arm takes the reaction, and the whole drive disappears inside the frame of the machine. It is the same 47 mm helical-worm gear set as the foot-mounted version, so nothing about the gearing or the ratio range changes.

Direct Mounting in a 47 mm Frame

Because the output shaft is the driven shaft, runout and misalignment are governed by one joint rather than two. The 47 mm frame handles continuous duty with a maximum housing rise of 40 C and an oil rise of 50 C, measured during factory run-in; gearing is 20CrMnTi ground to grade 6~5 with noise held within 60~68 dB. Housing is cast iron at HBS190-240, bored in a single setup so the hollow bore and the worm axis stay concentric.

SA47 Specification Table

Typical duty points where this unit is specified:

• Agriculture and food processing
• Textile, leather and paper industry
• Conveyors, mixers, agitators and hoists
• Metal processing and forming lines
• Chemical and environmental plants

Lead Time, Price and Drawings

We quote the SA47 from the interface data, not from a catalogue guess: shaft diameter, keyway or shrink-disc preference, ratio and duty description are the four answers we need. Standard production is 5-10 weeks, urgent units can be pulled forward, and every unit leaves the plant factory-tested with a one-year warranty.

The SF Series at a Glance

All eight frames share one gear set family, so a change of frame size rarely means a change of mounting: S is the shaft-mounted version, SA has a hollow output, SAF adds a flange and SAZ uses a torque arm and reaction rod.

Selection Example: Rotary valve on a dust line

Take a 2.2 kW motor at 1420 rpm driving a rotary valve at 71 rpm. The ratio follows directly: 1420 / 71 = 20, so i=20 fits with margin. In this case the torque arm takes the reaction, so the duct needs no steel frame. 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.

Sizing flow: motor speed, target output speed, torque, service factor.

Where This Series Works in Practice

Flour mill screw conveyors

A flour mill standardised on SF57 gear reducers for its screw conveyor network. One spare-part pool now covers fifteen drives, and the smooth helical input stage keeps noise low in the packing hall.

Sawmill crusher drive

A wood-processing plant drives its crusher with an SF97 unit. The cast-iron housing (HBS190-240) resists impact, and the high-torque worm stage starts the crusher under load without a soft-starter.

Technical Questions, Answered

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.

Common application areas for right-angle helical-worm 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.