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Gearboxes & Speed Reducers Attributes

A speed reducer is an enclosed gearset that takes motor speed down and torque up: worm, helical, helical-bevel, hypoid, planetary and shaft-mount, from 1.33 in worm centers up to industrial gear units. Two buyers shop it: the planner replacing a failed unit on a conveyor, who needs an exact configuration match, and the OEM engineer sizing a drive, who arrives with a motor frame, an output speed and a load.

The spec that decides the sale is rarely on the page. Ratings live in manufacturer tables keyed by frame size and ratio, published as mechanical horsepower with thermal capacity on a separate sheet, so a record with one HP number is ambiguous. Configuration hides in the part number rather than in fields: F724-60-B5-G carries size, ratio and the flange/shaft arrangement, and nothing in the catalog decodes it.

Then variants multiply. One worm gearbox size crosses ratios from 5:1 to 60:1, input styles (56C, 140TC quill, solid shaft, IEC B5), output configurations (solid, hollow bore, taper-bushed) and hands. Torque arrives as in-lb, ft-lb and Nm on the same rail.

Core

Every SKU needs these. Without them the record is not a product, it is a row.

Reducer Type
enum
Right-angle worm

Sets efficiency, mounting envelope and whether the drive back-drives. Worm, hypoid and planetary are not interchangeable at the same ratio.

Gear Ratio
text
60:1

The first filter every buyer touches. With input speed it gives output rpm; with input HP it gives output torque.

Worm Center Distance / Nominal Size
number · in
2.4 in

The size index the entire rating table is keyed to, and what a replacement must match to reuse the existing base and shaft height.

Input Style & Frame
enum
140TC quill (NEMA C-face)

Decides whether the buyer's motor bolts on. C-face quill, IEC B5 flange and solid input shaft need different motors and adapters.

Output Configuration
enum
Hollow bore, single

Hollow bore mounts onto the driven shaft; a solid shaft needs a coupling and a base. The wrong one is an immediate return.

Output Bore / Shaft Diameter
number · in
1.250 in

Must match the driven shaft or the coupling bore. Taper-bushed units need the bushing bore carried as its own value.

Mounting Position
enum
M1 (horizontal, foot mount)

Gear units are oil-filled to the position they were ordered in. A unit run in a position it was not filled for is under-lubricated.

Housing Material
enum
Cast iron

Cast iron for shock load and heat rejection, aluminium for weight and washdown. Also drives freight weight and corrosion behaviour.

Manufacturer Part Number
identifier
F724-60-B5-G

The only key that survives cross-reference between distributor, manufacturer, and the tag on the planner's failed unit.

Differentiating

What buyers actually compare on. This is where catalogs win or lose the filter.

Maximum Output Torque
number · lb-in
5,020 lb-in

The number a drive is actually sized against, and a live numeric facet on distributor rails. Worthless unless the unit is governed.

Nominal Input Horsepower
number · HP
1.5 HP

Matches the reducer to the motor the buyer already owns. This is the mechanical rating — label it as such and carry thermal separately.

Output Speed at 1750 rpm Input
number · rpm
29 rpm

How buyers shop when they know the conveyor speed they need. Distributors put it in the product title next to the ratio.

Overhung Load Capacity
number · lb
900 lb

Governs whether a sprocket or sheave can hang off the output shaft. Carry the load-center distance it was rated at alongside it.

Thermal Horsepower Rating
number · HP
1.8 HP

The real limit in continuous duty. In still air it sits below the mechanical rating, and it is why correctly selected units still cook their oil.

Compliance & identifiers

Standards, regulatory data, and the identifiers channels reject you for missing.

AGMA Rating Basis
enum
ANSI/AGMA 6034-C21

Tells the buyer what the published rating means. Enclosed wormgear reducers rate to a different standard than industrial enclosed gear drives.

ATEX / IECEx Marking
text
II 2G Ex h IIB T4 Gb

Ex-rated gear units are separate part numbers with different surface-temperature and lubricant limits. With no field, they cannot be filtered.

GTIN / UPC
identifier
00692762345678

Required by Amazon Business and most reseller item feeds. The join key for every marketplace listing and syndication target.

Country of Origin
identifier
United States

Customs entry, USMCA claims, and government or Buy America line items that reject a SKU carrying no origin.

The fields that aren't in the schema at all

What most gearboxes & speed reducers catalogs are missing.

The table above is the schema most catalogs already have. These are the attributes that usually aren't in it — each one surfaced by a signal from the live market rather than by an audit of what's already there. This is what Anglera's Schema Foundry does on a real catalog, in this category.

Supplier signal
+ Thermal Horsepower Rating

Boston Gear's 700-series tables state that published ratings are mechanical, not thermal, and print thermal capacity on a separate sheet. Distributor PDPs carry one HP number and never say which.

A unit selected on the mechanical rating overheats in continuous duty, the oil degrades, and it comes back as a warranty claim against a correct selection.

Competitor signal
+ Overhung Load Rating Basis (load-center distance)

Grainger exposes an Overhung Load Capacity facet and prints values like 900 lb in product titles. The distance from the shaft shoulder the rating was taken at appears nowhere on the page.

A sprocket mounted out at the shaft end sees far more load than the rating assumed. Output bearing and shaft fail early, and the reducer takes the blame.

Supplier signal
+ Mounting Position / Oil-Fill Orientation

Gear-unit makers fill oil to the ordered mounting position (M1 through M6) and require refill if it changes. Distributor records say 'any position' or carry no field at all.

A reducer ordered for M1 and installed vertically runs under-lubricated and fails inside warranty. Nothing in the order record shows the position it was filled for.

Search signal
+ Output Shaft Hand / Rotation

Boston Gear encodes flange and shaft arrangement in the part-number suffix (-B5- versus -B7-), and buyers ask outright for left-hand or right-hand output. Catalogs list only the MPN.

The hollow-bore unit arrives with the shaft on the wrong side of the conveyor. Return, reorder, and a lost install day on a scheduled outage.

Supplier signal
+ Backlash (arcmin)

Planetary gearhead makers offer the same frame in standard, precision and ultra-precision backlash classes. Distributor catalogs list one SKU per ratio with no backlash field.

Servo positioning applications cannot be quoted from the catalog. The RFQ goes to the manufacturer's own site and the distributor never sees the order.

How Schema Foundry finds these

Messy in, governed out.

The same value, spelled every way power transmission & bearings suppliers spell it. A filter only works once they agree.

Maximum Output Torque
925 in-lb925 lb-in77 ft-lb104 Nm925 in.-lbs.77.1 FT/LBS
925 lb-in

Distributor rails carry in-lb, ft-lb and Nm in one field. A numeric facet mixing them ranks 104 Nm below 925 lb-in — the same reducer.

Gear Ratio
30:130/130 to 1301:30Ratio 30
30:1

Suppliers ship '30 to 1' as free text and a few invert to 1:30. Free-text ratios never bucket, so the 30:1 facet misses half the SKUs.

Input Style & Frame
56C56 C-Face56C Quill140TC140TC Quill InputIEC B5 90
56C quill (NEMA C-face)

NEMA C-face and IEC B5/B14 are different bolt circles. Collapsing both to 'flange input' ships a motor that will not bolt up.

Reducer Type
Worm gearRight Angle WormWormgearRight-angleRA WormWorm drive
Right-angle worm

'Right angle' also covers bevel and hypoid. Merging them puts low-efficiency worms in the same bucket as hypoids at the same ratio.

What buyers ask

Every one of these should be answerable from the attributes above. If it isn't, that's a gap.

  • What output torque do I get at 25:1 with a 1 HP motor on it?
  • Will a 56C motor bolt straight to this or do I need an adapter?
  • Is this rated thermally for continuous duty, or is that a mechanical rating?
  • Hollow bore or solid shaft, and what bores can I get in this size?
  • How much overhung load will the output shaft take with a chain sprocket on it?
  • Can I mount this vertically, or is it filled for horizontal only?
  • Is the output shaft on the left or the right side?
  • Does it ship filled with oil, and is the lube food-grade?

What channels require

The same SKU, different mandatory fields per destination.

Distributor's own faceted catalog
Reducer TypeGear RatioWorm Center Distance / Nominal SizeInput Style & FrameOutput ConfigurationMaximum Output Torque
Amazon Business
GTIN / UPCManufacturer Part NumberCountry of OriginGear RatioMaximum Output TorqueHousing Material
Reseller item feeds (Grainger, MSC, Fastenal)
Manufacturer Part NumberGTIN / UPCCountry of OriginGear RatioOutput Speed at 1750 rpm InputOverhung Load Capacity
CAD and RFQ portals (TraceParts, Thomasnet)
Manufacturer Part NumberReducer TypeWorm Center Distance / Nominal SizeOutput Bore / Shaft DiameterMounting PositionInput Style & Frame

Gearboxes & Speed Reducers data, in practice

What is the difference between the mechanical rating and the thermal rating?

Mechanical horsepower is what the gearset and bearings will carry. Thermal horsepower is what the housing can shed as heat before the oil overheats and breaks down. Boston Gear's 700-series tables say outright that the published ratings are mechanical, not thermal, and print thermal capacity separately. A continuous-duty selection has to satisfy both, and in still air at elevated ambient the thermal number is usually the smaller of the two. If the record carries a single HP figure, no buyer can tell which one they are looking at. Carry both, labelled.

Should service factor be a stored attribute on the SKU?

No. Service factor is an application input, not a product property. Selection runs Design HP = application load x service factor, and the buyer supplies the factor from their own duty cycle: load character, starts per hour, hours per day. What the record must carry is the manufacturer's rating and the standard it was rated against — ANSI/AGMA 6034 for enclosed cylindrical wormgear speed reducers and gearmotors, ANSI/AGMA 6013 for industrial enclosed gear drives. Store the rating and let the buyer apply the factor. Publishing one service factor per SKU asserts a duty cycle you do not know.

Why can't gear ratio just be stored as a number?

Because it is ordered as a pair and printed six ways. Suppliers send 30:1, 30/1, '30 to 1' and a bare 30, and a few invert it to 1:30. Stored as text the facet fragments; stored only as a number you lose the convention and cannot render it back. Carry the reduction as a number for filtering and sorting, keep the display form governed to 30:1, and reject inverted values at ingest. A speed reducer whose numeric ratio lands below 1 is either a speed increaser or a data error, and both need catching before they hit the rail.

Does ATEX genuinely apply to gearboxes, or is that a motor and pump concern?

It applies. Gear-unit makers publish explosion-protected variants of standard product — SEW's MC industrial gear units, for example, are offered in ATEX design for Group II categories 2/3G and 2/3D, covering zones 1, 21, 2 and 22. The marking is a variant-level attribute, not a family-level one: the same gear unit family carries a standard version and an Ex version under different part numbers, with different surface-temperature and lubricant constraints. If the schema cannot separate them, an Ex enquiry cannot be filtered and gets quoted as standard.

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