The M3PHF90 gear reducer is the largest frame of the horizontal industrial range, and it is chosen for one reason above all others: torque density at the top of the ladder. Three all-helical stages on parallel axes carry the load, the foot-mounted cast-iron housing bolts to a conventional pad, and the low-speed shaft is hollow so the driven machine shaft enters the gear unit directly instead of being joined to it through a coupling.
The Top Frame of the Horizontal Industrial Ladder
Frames across this family rise from size 50 to size 90, and the size number tracks torque capacity rather than motor power. A size 90 unit is normally specified where the driven machine is an inertia load - a loaded conveyor, a mill shell, a rake mechanism - that keeps asking for torque long after the motor has started. The split housing lets maintenance open the top half in place for tooth and bearing inspection, and the ground, case-hardened helical wheels run in a common oil sump sized for thermal equilibrium at continuous duty.
M3PHF90 Code, Position by Position
| M3 | Industrial gear unit series, three gear stages |
| P | All-helical gearing on parallel axes (an R code would add a bevel right-angle input) |
| H | Hollow low-speed shaft with key or shrink-disc connection (S denotes solid output) |
| F | Foot mounting to a prepared foundation (T denotes a torque-arm reaction) |
| 90 | Frame size 90, the upper end of the horizontal band 50 to 90 |
Read this way the designation is a specification in miniature: layout, shaft type, mounting and size are all stated by one string. That is deliberate. On a large plant the contractor, the millwright and the stores department all work from the same code, so a size-for-size change needs no interpretation - the foundation pattern, the bore and the motor interface are already fixed by the frame number.
Installations that call for exactly this arrangement:
- Head drives on shiftable and overland conveyors in bulk mining
- Kiln, cooler and dryer shell drives on existing trunnion bearings
- Heavy apron feeders and wobbler feeder shafts under primary crushing
- Autogenous and semi-autogenous mill auxiliary drive points
- Thickener and clarifier rake mechanisms in tailings circuits
- Reclaim and blending conveyors inside stockyard tunnels
Continuous Duty Points That Need This Capacity
A top-frame unit is not bought for a short or intermittent duty; it is bought where the drivetrain is expected to run loaded for years with no scheduled shutdown beyond oil changes. Where the machine shaft is long or only lightly supported, a hollow output can be the wrong answer, because the shaft must carry the gear unit as well as its own load. WGT checks that detail - shaft stiffness, distance to the nearest bearing and the overhung pull of the driven element - before confirming that the hollow-shaft foot build is right for the position.
Drawing Review, Selection and Delivery
WGT issues the industrial range catalogue and the size 90 outline drawing as PDF downloads, so the bore diameter, keyway or shrink-disc seat, foot bolt pattern and motor interface can be matched against the installation before any order is placed. Send the driven machine, the motor power and speed, the target output speed, the machine shaft diameter and the daily running profile; the rated torque is checked with the duty service factor and a written quotation follows. Each unit is factory-tested, packed in an export wooden crate and covered by a one-year warranty.
Selection Example: Overland conveyor head drive
Take a 200 kW motor at 1490 rpm driving a shiftable overland conveyor head shaft at 10 rpm. The ratio follows directly: 1490 / 10 = 149, so the three-stage band with a raised service factor covers the head-end torque. In this case the size 90 frame and the hollow bore let the drive ride the head shaft directly, so the unit moves with the conveyor as the face advances. 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 M3 Series
| Model | Centre distance | Output | Typical duty |
|---|
| M3PSF50 | size 50 | solid shaft, foot | conveyors, feeders |
| M3PSF60 | size 60 | solid shaft, foot | crushers, mixers |
| M3PSF70 | size 70 | solid shaft, foot | ball mills, shredders |
| M3PSF80 | size 80 | solid shaft, foot | kilns, heavy conveyors |
| M3PSF90 | size 90 | solid shaft, foot | mill and kiln drives |
| M3RSF50 | size 50 | solid shaft, foot, right-angle | inclined conveyors, elevators |
| M3RSF60 | size 60 | solid shaft, foot, right-angle | screw classifiers, feeders |
| M3RHF70 | size 70 | hollow shaft, foot, right-angle | agitators, drum drives |
| M3PHT80 | size 80 | hollow shaft, torque arm, parallel | shaft-mounted conveyors |
| M3RHT90 | size 90 | hollow shaft, torque arm, right-angle | heavy shaft-mounted drives |
The table below shows the M3 industrial range: P builds are all-helical on parallel axes, R builds add a bevel input stage for a right-angle drive; S / H describe the low-speed shaft and F / T the mounting.
Application Cases
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.
![industrial gearbox applications - conveyor mixer crusher wastewater]()
Figure: typical industries that use the WGT S-series gear reducers.
Frequently Asked Questions
How do I install the unit on an inclined conveyor?
Mount the unit with the output shaft horizontal or as recommended for your mounting position, and choose the anti-run-back option so the loaded belt cannot drive the gearbox backwards when power is cut. Tell us the incline angle when you order.
What is the difference between a keyed hollow shaft and a shrink-disc connection?
A keyed hollow shaft is the economical choice for normal torque and easy maintenance. A shrink-disc connection transmits higher torque with zero backlash and no keyway wear, and is preferred for reversing or high-torque duties.
Can I get a CAD drawing or 3D model for my design review?
Yes. Send us the model and ratio and we provide a 2D dimension drawing and a 3D STEP model for your review, usually the same working day. Drawings follow the layout of the original series so they drop into your existing assembly.
Site Survey Data? We Size It for You
Have the machine data but not the model? Not sure which model fits? Try our online WGT Motor & Gearbox Online Selection System to match motor power, ratio and mounting in one minute.
Send the conveyor length, belt speed, drive pulley diameter or the machine duty description. We run the full selection - ratio, frame, service factor - and return the datasheet with the quote. Looking for a gearbox for crusher? Tell us the duty point and we will confirm the model in writing.
