The MC2PLSF08 parallel shaft gearbox is the second-largest frame in the compact two-stage family, and it is normally specified by plants that have already learned what an undersized drive costs them. Two helical stages in one plane, a footed cast case, a solid keyed output, motor mounted alongside - the architecture is the same as every other frame in the line. What changes at this size is the amount of material in the case, the width of the gear faces and the bearing selection, and those three things are what a process engineer is really buying when the duty behind the drive cannot be interrupted.
How the 08 Differs From the Frames Beneath It
Frame steps in this range are incremental on a drawing and considerable on a plant floor. Going from an 06 or 07 to the 08 buys a wider centre distance, a heavier output shaft and a deeper oil sump, which together move the unit away from its thermal ceiling. A smaller frame can carry a continuous load perfectly well while sitting close to the limit of what its oil volume can dissipate; the 08 doing the same work holds a temperature that leaves room for a hot afternoon, a fouled cooling surface or a season of slightly heavier material.
There is a second, quieter benefit: the 08 shares fasteners, seals and oil grade with its smaller neighbours, so a store room built around this series does not need a separate shelf for the top end. Plants that standardise on one line of units find that the maintenance crew learns the routine once and applies it everywhere.
Reading the Order Code Field by Field
The model string is a compressed record of decisions taken at the enquiry stage. Reading it in sequence avoids the common mistake of ordering a frame that fits the power but not the mounting.
| MC | Industrial gear unit of the compact multi-stage type |
| 2 | Two reduction stages in helical gearing |
| P | Parallel shafts, input and output on the same horizontal plane |
| L | Long case profile with cast foot pads and a side inspection cover |
| S | Solid output shaft with parallel key, ready for a coupling hub |
| F | Foot mounting for horizontal installation on a bedplate |
| 08 | Frame size, second from the top of this range |
What the string does not contain is the ratio and the mounting position, and those are the two fields that cause most re-quotes. Always write both on the enquiry, and add the drawing number if the unit has to fit an existing bedplate without modification.
Sizing a Drive That Is Never Allowed to Stop
Three numbers drive the selection: motor speed, required output speed and absorbed torque. Divide the first by the second and you have the ratio; multiply the third by the service factor your duty class demands and you have the figure the frame must exceed. Where the 08 separates itself from the smaller frames is in the service factor. A conveyor that can be emptied before starting can live with a modest factor. The same conveyor with a loaded belt, a history of jam clears, or a plant where a stoppage costs more than a gearbox, justifies a larger factor - and the 08 is the frame that absorbs it without pushing the unit to its thermal edge.
Ambient conditions belong in the same calculation. A unit standing in still, hot air inside a closed gallery loses cooling capacity compared with the same unit on an open frame outdoors, and the correction is made on paper rather than discovered in service. State the site conditions plainly and let the factory apply them.
Plant Positions That Call for This Size
Vertical duties this frame is routinely installed on:
- Raw mill and cement mill auxiliary drives in grinding plants
- Overland belt conveyors along mine site haul roads
- Reclaim scraper and stacker conveyor drives at stockyards
- Lime kiln feed and discharge conveyor drives
- Bulk fertiliser blending and bagging line drives
- Chip handling conveyor drives in pulp and paper mills
These are all duties where the drive is expected to run for years with routine attention and no heroic intervention. That expectation is precisely what a frame of this size is built to meet.
Setting a Large Case on a Steel Frame
A unit at this weight will not be persuaded into alignment by tightening bolts. The sequence that works starts with the structure: check the mounting pads for flatness and for twist across the diagonals, because a steel frame that has been welded on site is rarely as true as the drawing. Pack shims under each foot as solid stacks, bring the case down with the lifting gear still attached, and read a precision level along both shaft axes before any bolt is torqued.
With the case level and the bolts pulled to their figures, alignment of the coupling comes next. Rough alignment by straight edge, then dial indicators or a laser set, then a bar-over by hand to feel for a tight spot. The warm check matters on conveyor duty: run the drive under load for an hour and read alignment again, because the pulley and the belt tension settle and pull the train out of the cold setting.
Condition Habits for a Three-Shift Drive
The routines that actually protect a unit this size are simple and boring. Sight glass read at the start of every shift against a painted mark, not from memory. Sump temperature logged at the same point once a week. Breather wiped when the plant is dusty, and changed when it stops passing air. Oil sampled at the interval in the manual, with the first change brought forward to clear running-in debris.
Beyond that, listen. A gear set that starts to whine at a particular load band is telling you something about mesh contact that no gauge will show until damage is visible. Recording the observation and the load at which it appears gives a service engineer far more to work with than a general complaint that the unit is noisy.
Documents That Make a Firm Offer Possible
A firm offer on an 08 needs the motor rating, speed and starting method; the required output speed or ratio; the driven machine and its duty pattern including starting condition; the mounting position and any restriction on overall height; shaft and bore details where the unit must match existing hardware; and the site ambient, altitude and hazardous-area classification if any. Paint specification, nameplate language and inspection documents complete the picture. Send those in one message and the frame, ratio and options are confirmed in a single exchange, with the delivery slot resting on a specification rather than an assumption.
Selection Example: Cement mill auxiliary conveyor in a closed gallery
Take a 1480 rpm four-pole motor turning a mill feed belt pulley at 21 rpm. The ratio follows directly: 1480 / 21 = 70.5, so a ratio near i=71 is ordered and the gallery ambient is stated on the enquiry so the thermal capacity can be checked, not assumed. In this case the wider gear faces and deeper sump hold temperature inside a closed gallery where a smaller casting would run against its cooling limit all shift. 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
Dust-extraction fan bank
An environmental-equipment plant uses reducers on the rotary valve feeders of its dust-extraction systems. Compact size, quiet running and food-grade oil options made the approval easy.
Steel mill run-out table
On the run-out table of a small steel mill, 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.
![industrial gearbox applications - conveyor mixer crusher wastewater]()
Figure: typical industries that use the WGT S-series gear reducers.
Frequently Asked Questions
Should I choose a solid or hollow output shaft?
A solid shaft with a keyed coupling is the flexible, conventional choice. A hollow shaft takes the driven shaft directly with a key or shrink disc, removing one coupling and one alignment step; it is preferred where space or alignment access is limited.
How do I match the gear unit to my existing foundation?
Send the nameplate or the outline drawing of the unit being replaced. Frame dimensions follow the common industry dimension ladder, so foot holes, shaft heights and flange bolt circles normally match without redrilling foundations.
What ratio range does an industrial gear unit cover?
The range spans from low single-digit reductions to very high ratios by combining stage counts: two-stage builds for the lower band and up to five-stage builds for the highest reductions, with intermediate ratios available between catalogue steps on request.
Send the Nameplate - Get the Equivalent Frame
Matching an existing installation? Not sure which model fits? Try our online WGT Motor & Gearbox Online Selection System to match motor power, ratio and mounting in one minute.
Photograph the nameplate or note the model and ratio. We identify the equivalent frame, confirm the torque margin and return a quotation with the outline drawing - usually within one working day. Looking for a gearbox for wastewater treatment? Tell us the duty point and we will confirm the model in writing.
