The M3PVSF40 vertical parallel shaft gear unit takes the compact upright line one frame higher: still three helical stages with no bevel set, output turned straight down, but with visibly more metal around the meshes. The step from size 30 to 40 usually arrives when a process vessel grows - a thicker agitator shaft, a deeper basin, longer rake arms - and the torque demand crosses the line where the smaller casting no longer carries the duty with margin. Mounting logic stays the same as the rest of the family: the unit hangs from its top flange face, the motor bolts alongside, and nothing in the drivetrain changes direction.
Scaling the Upright Line Up One Frame
What the 40 frame buys is not just a bigger bore. The larger casting raises the oil volume, which lowers the operating temperature on continuous duties and slows the ageing of both oil and seals. The shaft journals are stiffer, so overhung loads from long agitator shafts deflect the output less, and the extra mass damps the vibration that tall, slender shafts tend to feed back into a gearbox. For plants that already run size 30 units on smaller vessels, keeping the same family means one set of spare seals, one oil grade and one maintenance habit across the whole vertical fleet.
The honest limit is headroom: the 40 casting is taller, and inside low vessel sheds the top flange may sit closer to the roof. Measuring available height before ordering is cheaper than discovering it with the unit on the crane hook.
Reading the Designation on the 40 Frame
| M | Industrial multi-stage gear unit family |
| P | Parallel helical stages, input and output in one plane |
| V | Vertical build, output shaft pointing downward |
| S | Solid ground output shaft with parallel key |
| F | Foot pads plus top flange face for vessel mounting |
| 40 | Frame size, one step above the compact 30 |
As always in this family, the frame fixes the hardware and the ratio is chosen separately to set process speed. Stating the absorbed torque together with the target rpm lets the factory pick the ratio that lands the duty in the efficient middle of the mesh rather than at either edge.
Torque Headroom and Why It Matters
Vertical agitator drives rarely see steady load: solids settle, viscosity drifts with batch temperature, and a start-up after a shutdown can double the torque for a few seconds. A frame chosen with barely any margin runs those peaks through its tooth flanks every batch. The 40 frame is typically specified precisely to buy that headroom on vessels where a 30 would run permanently near its limit. The practical test is simple - if oil temperature stabilises well below the alarm band and the mesh stays quiet at start-up, the frame is right; if the oil runs hot and the housing hums on every restart, the next size up pays for itself in seal life.
Service profiles this build is regularly chosen for: Thickener and clarifier rake drives in mineral processing Vertical agitators on mid-size chemical and fermentation vessels Flash mixers and flocculation basins in water treatment trains Cooker and kettle drives in starch and glucose plants Top-entry stirrers on dye and pigment holding tanks Small cooling-tower and dosing-station gear sets
Setting the Unit on the Vessel Boss
Prepare the vessel boss first: clean the mating face, check it for flatness, and confirm the stud pattern against the drawing before the unit leaves the floor. Lift the unit into place, start all studs by hand, and tighten in a star sequence so the flange seats evenly - pulling one side down first tilts the face and shows up later as a seal weep on the low side. Only after the fixing bolts are torqued should the process shaft be coupled, and the shaft must carry no weight through the gearbox while it is being aligned.
Check motor rotation against the required shaft direction before closing the coupling guard - a reversed agitator on a thickening duty can compact solids in the wrong direction and stall the rake on first start.
Oil, Temperature and the Log Sheet
Fill to the plate quantity with the unit standing level and read the level at rest, not right after shutdown. On a continuously stirred vessel the oil reaches its stable temperature within a few hours, and that number - logged once a week in the same conditions - is the most useful single record the site keeps. A slow climb over weeks points to a fouled breather or a drifting ambient; a sudden jump points to the bearings or a coupling problem, and both are cheaper to meet with a trend line than with a breakdown.
Specifying Without Guesswork
A complete enquiry for this frame carries six facts: absorbed power or torque, required output speed, the process shaft diameter and its overhung load, the mounting posture, the medium in the vessel, and the daily running hours. Add a photo of the old nameplate and a note on the side clearance available for the motor, and the factory can confirm the build in one reply without a site survey.
Field Applications
Ship loader slew drive
A port terminal selected heavy-duty gear units for the travel drives of its ship loader. Salt-laden air is handled by the heavy-duty coating option, and spare seal kits are held on site for the annual service.
Sugarcane carrier drive
A sugar mill drives its cane carriers with industrial gear units sized for fully loaded starts. The generous torque margin covers cane jams, and the right-angle build keeps the motor clear of the carrier slat path.
![where gear reducers are used in industry]()
Where these units are installed across industry.
Selection Example: Typical duty point
Worked example for this frame - the motor runs at four-pole speed and the machine needs a slow output. Motor speed divided by the target output speed gives the ratio, rounded to the nearest available step, and the required torque with the service factor then fixes the frame size. Once the ratio is fixed, check the required output torque against the rating table with the service factor applied - that is what decides the frame, not the ratio alone.
![gearbox selection guide: speed, torque, service factor]()
How a ratio and a frame size are determined, step by step.
Frame Sizes and Typical Duties
| 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 size number is the key dimension that steps up torque capacity through the range: 50 to 90 in horizontal builds, 10 to 90 in vertical builds. Gearing philosophy is shared across the family.
From Duty Point to Delivery in One Working Day
Stop guessing the ratio. Engineers can size the unit themselves in the WGT Motor & Gearbox Online Selection System - input speed, torque and duty, get the model instantly.
Tell us what the machine does and how hard it works; we calculate the ratio, apply the service factor and send back the drawing and quotation within one working day, including sea-freight and air-freight options. Looking for a gearbox for steel mill? Tell us the duty point and we will confirm the model in writing.
Common Questions from Buyers
Why does low backlash matter, and what is the limit?
Backlash is the small free rotation between input and output. We hold it within 20 arcmin - tight enough for indexing tables, positioning drives and reversing applications, without the cost of a precision servo gearbox.
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.
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.
