The M3PVHF70 vertical hollow shaft gear unit is the mid-band vertical frame with a bored output: the process shaft passes up through the unit, is keyed inside the bore, and the gear unit itself becomes the shaft support. Above a scrubber sump, a digester or a deep pump column, that one change removes a coupling, a pedestal bearing and an alignment exercise from the top of the installation, and it shortens the whole drive stack by the height those parts used to occupy.
The Bearing Load Is the Selection
On a hollow vertical unit the load path runs from the impeller or pump bowl, up the process shaft, into the output bearing inside the housing. Radial load comes from shaft deflection and fluid unbalance; axial load comes as a thrust in one direction or the other depending on whether the machine pushes down into the liquid or pulls up. The bore and bearing set at size 70 are rated for the combination, but the figures have to be declared - a shaft that is two metres of 80 mm bar under a scraper blade is a very different bearing problem from the same bore carrying a short mixer. The frame is then chosen against the shaft interface rather than against torque, which is usually the looser of the two constraints at this size.
Reading the Designation
| M | Three-stage industrial gear unit family |
| P | Parallel-shaft helical gearing, no right-angle stage |
| V | Vertical axis, output facing down into the process |
| H | Hollow output shaft bored for the through-going process shaft |
| F | Foot and flange mounting on a headplate or steel frame |
| 70 | Frame size within the vertical range |
Inside the Housing
Three ground helical stages carry the reduction with overlapping tooth contact, so the drive turns quietly and spreads torque across several teeth at every instant. The gear train itself is not where a vertical unit earns or loses its reputation - the seal and the lower bearing are. The shaft seal at the bore is selected for what sits directly beneath the unit: vapour from a hot vessel, slurry mist above a scrubber, dust above a powder silo. Get that one component right and the unit runs for years; treat it as an afterthought and the oil finds its way out downward, which is the one direction a vertical unit cannot afford.
Machine groups this unit is specified into: Digesters and digester-drawing pumps at water plants Vertical agitators on flue-gas scrubber slurries Fish-transfer and aeration pumps on aquaculture sites Silo centre-drive stirrers on powder storage Vertical pipeline boosters in long pump shafts Deep-well pump line shafts in irrigation schemes Centrifuge bowl feeders at sludge dewatering plants Vertical ribbon mixers on fertiliser blending lines
Installation Notes That Actually Matter
The headplate must be machined flat and square, because tilt in the mounting face is transferred straight into the bore and the seal lip. Shaft end float is set to the drawing figure so the process bearings and the unit bearing share the thrust as designed. The breather goes in the position marked for vertical mounting, and the oil level is read at standstill in the shipped posture. Torque reaction is taken by the housing flange - never by the shaft - which is why the bolt pattern on the headplate deserves the same attention as the bore diameter.
Papers, Packing and Aftercare
Each unit leaves the works with a dimensional drawing, an oil chart per mounting position and a nameplate recording ratio, frame and arrangement. Bore size, keyway or clamp detail and the seal variant are agreed before release, so the delivered unit matches the drawing set the plant holds. Export packing is a braced wooden crate with the shaft protected for transit; spare seals and a set of mounting bolts are packed inside, because the parts a site needs on commissioning day are the parts that should never be missing.
Selection Example: Digestion tank top-entry agitator
Take a 55 kW motor at 1485 rpm turning the digestor shaft at 19 rpm. The ratio follows directly: 1485 / 19 = 78.2, so a ratio near i=78 is selected and the bore plus clamp detail are matched to the through-going shaft drawing. In this case the hollow bore carries the shaft straight through the tank roof, which removes a pedestal bearing and keeps the seal serviceable from above the deck. 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
Wood chipper line
A board mill drives its drum chipper with a heavy-duty gear unit. Knife engagement shocks arrive several times a second, and the case-hardened gearing with generous bearing spans has shown no measurable wear.
Fertiliser plant drag chain
A fertiliser complex runs drag-chain conveyors on industrial gear units in a corrosive atmosphere. The heavy-duty epoxy coating and FKM seals have kept the units presentable and leak-free through several campaign cycles.
![gear reducer industries served - WGT]()
Industry map: the sectors where the M3 series is most common.
Buyer Questions and Answers
What are the delivery lead times and shipping terms?
Standard lead time is 5-10 weeks ex-works, with popular ratios often available sooner. We quote EXW, FOB NINGBO / SHANGHAI or CIF, and urgent units can be air-freighted within 72 hours of payment.
What materials are used for the gears and shafts?
Gears are 20CrMnTi alloy steel, case-carburised to HRC58-62 over a tough HRC33-40 core. Input and output shafts are 42CrMo, quenched and tempered to HRC25-30. The housing is cast iron at HBS190-240.
M3 Series Model Overview
| 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 series is sized for continuous heavy duty rather than by motor power alone: the required torque with the service factor decides the frame, and the stage count (2 to 5) decides the ratio band.
Send the Nameplate - Get the Equivalent Frame
Matching an existing installation? 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.
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 reducer for woodworking machine? Tell us the duty point and we will confirm the model in writing.
