Question 1

What is a plug-in shaft for a right-angle speed reducer?

Accepted Answer

It converts a flexible-mount right-angle reducer's female (hollow) output bore into a male, keyed output stub so you can drive a sprocket, pulley, or coupling. The reducer turns the shaft through two central keyseats in its bore; the shaft then delivers torque at a keyed output end, one (single output) or both (dual output). So a single-output shaft has 3 keyseats (2 central drive + 1 output) and a dual-output has 4 (2 drive + 2 output), plus an axial retention tap at each output end and two retaining-ring grooves that hold the shaft in the reducer. Each loads into the configurator with all of that pre-placed and ships with a length of key stock.

Question 2

How do I pick the right size?

Accepted Answer

Match the shaft diameter to your reducer's output bore and choose single or dual output. The diameter then fixes the keyway size (ANSI B17.1 square key) and the retention-tap thread. If you're replacing a catalog part, the cards cross-reference the McMaster 6771K SKUs. Pick the card whose diameter, length, and output count match.

Question 3

Which reducers do the generic plug-in shafts fit?

Accepted Answer

The single- and dual-output cards fit the standardized NEMA-input aluminum worm-reducer pattern (often called the NMRV or aluminum-worm pattern) that the McMaster 6771K shafts replace. The same output bores (3/4, 1, 1-1/8, 1-1/4, 1-3/8 inch) appear across IronHorse WGA, WorldWide Electric CALM, and Motovario NMRV gearboxes, so a card matched by bore diameter, length, and output count fits that family. Confirm the bore and length against your reducer before ordering; we verify the geometry against your unit or old shaft before cutting. (The Dodge Tigear-2 cards are a separate, Dodge-specific pattern.)

Question 4

Do you make hollow-to-solid conversion shafts for Boston Gear / IronHorse / WorldWide worm reducers?

Accepted Answer

Yes. The Hollow-to-Solid Conversion cards turn an installed cast-iron worm reducer with a hollow output bore into a solid keyed output — no OEM sells this for the cast-iron worm line. The shaft drops into the reducer's existing hollow bore, is keyed to the hub's furnished key, held by the hub set screws and a retaining ring, and presents a keyed output stub. Boston 700 (718/721/724/726/732), IronHorse WG (175-325), and WorldWide HdR share the same size envelope, so one card covers all three by center-distance size. Bore and output dimensions come from the OEM catalogs and the body length from IronHorse's own CAD; Boston units are bored to size, so confirm your bore code and we verify against your reducer before cutting.

Question 5

What keyway and retention thread does each size use?

Accepted Answer

All keyways are a standard ANSI B17.1 square keyseat sized to the shaft diameter (3/16″ up to 7/8″, 1/4″ through 1-1/4″, 5/16″ at 1-3/8″). There are two central keyways where the reducer drives the shaft, plus one at each keyed output end (single = 3 keyseats, dual = 4). Each output end also carries a UNC retention tap (1/4-20, 3/8-16, or 1/2-13 by size) for a washer-and-bolt that holds the driven component on. Every dimension stays editable in the configurator.

Question 6

What material are these machined from?

Accepted Answer

The cards default to 1045 medium-carbon steel, a good general-duty reducer-shaft material. For higher strength switch to 1144 stress-proof or an alloy in the configurator. Material certs (MTRs) are available on request.

Question 7

Are the dimensions exact to the original shaft?

Accepted Answer

The shaft diameter, overall length, keyed-output length, and retention-tap thread are taken from the published catalog data; the full feature structure, the two central reducer-drive keyseats, the output keyseat(s), and the two retaining-ring grooves, is confirmed against the McMaster CAD drawings (6771K439 single, 6771K441 dual). The exact keyway lengths, ring-groove dimensions, the small drive-zone turn-down, and the feature positions for sizes other than 1-3/8″ are standard-derived/scaled and confirmed against your reducer or your old shaft before we cut. The drawing title block stamps the source SKU so any deviation is visible to you and to us.

Question 8

Do you make the Dodge Tigear-2 plug-in shaft kits (13PLUGIN through 47PLUGIN)?

Accepted Answer

Yes, all ten case sizes. The Tigear-2 architecture differs from the generic plug-in shafts: a stepped shaft (bore-riding body with a smaller keyed output stub), a single central bore keyseat driven by the reducer hub's furnished key, two snap-ring grooves for axial retention, and no end tap (the hub's set screws bear on the shaft). Stub diameter, projection, overall length, and both key sizes come from the Dodge catalog, and the body geometry is taken from Dodge's own CAD models. Like Dodge's kits, these fit standard-max-bore Tigear-2 reducers only.

Question 9

My size or reducer isn't listed.

Accepted Answer

These cover the common 3/4″ through 1-3/8″ flexible-mount right-angle reducer shafts in single and dual output, plus the Dodge Tigear-2 kit sizes 13 through 47. For another diameter, length, brand, or a different keyway, load the closest card and edit it, or send us a print or the old shaft and we'll match it.

Gearbox Plug-In Output Shafts

Plug-in shaft sizes

Single Output

Dual Output

Dodge Tigear-2

Hollow-to-Solid Conversion

Frequently Asked Questions