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NTN roller bearings laid out on a workbench for gearbox overhaul identification

FAQ · NTN gearbox & reducer bearings

NTN Gearbox Bearing FAQ: Shaft Positions, Suffixes and Paired Sets

Specify NTN gearbox bearings by shaft position, not just size. Answers for gearbox repair leads, reliability engineers and technical buyers preparing a reducer overhaul enquiry with oemntn.com, NTN authorized distributor in Hong Kong.

Most asked

The two questions behind most reducer overhaul enquiries

A complete list and clearly marked paired sets are what make a quote exact. These two answers cover what to send and how to mark it.

Q · 01

What should a complete reducer bearing list include?

A complete reducer bearing list gives the reducer model, the shaft position of every bearing, the full NTN designation with suffixes, any paired arrangement, the overhaul parts drawing, quantities, destination country and postcode, and the required arrival date. With that, each line can be quoted against the original specification.

  1. 01Reducer modelFrom the gearbox nameplate
  2. 02Shaft positionInput, intermediate or output; locating or non-locating end
  3. 03NTN suffixFull designation incl. clearance and cage
  4. 04Paired arrangementWhich bearings work as a set
  5. 05Overhaul parts drawingShows where each line fits
  6. 06Quantity per linePieces or complete sets
  7. 07DestinationCountry and postcode
  8. 08Required arrival dateWhen the overhaul needs parts on site

Designation incomplete? Attach clear photos of the bearing markings. See photo guidelines

Q · 02

How should paired bearings be identified in an enquiry?

Mark paired bearings as one set: list them together, give their shared shaft position, state the paired arrangement and give the quantity in sets. That way they are quoted as one coordinated set, not as separate single items that lose the pairing and arrangement requirement.

Example enquiry line layout

SET A Output shaft Locating end
  • Bearing 1 — full NTN designation + suffixin set
  • Bearing 2 — full NTN designation + suffixin set
  • Arrangement as per original specificationQty: sets
  • ✓Group paired bearings under one set label
  • ✓State the arrangement given by the original specification
  • ✓Give quantities as complete sets, not loose pieces

Browse by topic

NTN reducer bearing questions by category

Each category follows one stage of an overhaul enquiry, from selection and suffixes to receiving the goods.

01Selection & Suffixes

Our shop records show the same base number with different clearance or cage suffixes. Which one should we buy?

Buy the execution specified by the equipment's original specification, not the most recent purchase record. The base number gives the bearing type and size; the suffixes define clearance and cage, which decide whether it suits the shaft position and operating conditions.

Send every variant you found together with the reducer model and shaft position. We keep the original NTN suffix through the whole enquiry and flag any conflict before quoting.

Our overhaul list does not separate locating and non-locating positions. Is that a problem?

Yes. Without that split, a bearing can be selected or fitted in the wrong position. The locating end holds the shaft axially; the non-locating end allows axial movement, so the bearings at the two ends are often different.

Mark each line with its shaft and end. The shaft position diagram below shows how to label them.

Can you quote from bore, outer diameter and width only?

Dimensions alone are not enough for a gearbox position. Several NTN executions share the same boundary dimensions but differ in suffix, internal design or cage.

Send dimensions together with the reducer model, shaft position and any readable marking, so the original designation can be confirmed before the quote.

Which NTN bearing types can one overhaul list cover?

One list can cover every position in the reducer: cylindrical roller bearings for gear shafts and radial loads, tapered roller bearings for combined loads, and spherical roller bearings for heavier shafts with some misalignment.

Supporting positions are covered too: deep groove ball, angular contact ball, thrust and needle roller bearings. Browse NTN gearbox bearings

02Paired Arrangement

Will paired bearings be quoted as separate single items?

No. Bearings marked as a pair are quoted as one coordinated set, so the pairing and arrangement requirement stays attached to the line.

That only works if the enquiry shows they are a pair. List them under one set label with the shaft position.

We are not sure whether two bearings on one shaft are a matched pair. What should we send?

Send the overhaul parts drawing, the full markings of both bearings and photos showing how they sit on the shaft.

We clear up the arrangement before quoting. Nothing is assumed or changed without your confirmation.

Can one enquiry combine paired sets and single bearings from different shafts?

Yes. Input, intermediate and output shaft bearings, paired or single, can go into one complete overhaul parts list.

Keep each line tied to its shaft position so the quote follows the same structure as your parts drawing.

Illustrated answer

How do I label reducer shaft positions in a bearing enquiry?

Label every bearing with its shaft (input, intermediate or output) and its end (locating or non-locating). Those two labels, plus the full NTN suffix, identify the exact bearing a position needs.

Opened industrial reducer showing input, intermediate and output shafts with bearing positions
Shaft position diagram. Each shaft has a locating end (L) and a non-locating end (NL).

  1. A · Input shaft

    The high-speed shaft driven by the motor

    Label it e.g. "Input – L" and "Input – NL".

  2. B · Intermediate shaft

    Carries the gear stages between input and output

    Multi-stage reducers may have more than one; number them.

  3. C · Output shaft

    The low-speed, high-torque shaft to the driven machine

    Often where heavier roller bearings and paired sets sit.

EndFunction
Locating (L)Fixes the shaft axially, takes axial load
Non-locating (NL)Allows axial movement of the shaft

Identification gaps

What if the designation is incomplete or the nameplate is unclear?

Send clear photos of the bearing markings with the reducer model and shaft position. Identification gaps are closed before any quote is accepted, so the exact execution and complete set are confirmed rather than guessed.

Marking photo checklist

  • 1Clean the face first. Wipe oil and debris off the ring face where the marking is stamped or etched.
  • 2Use side light. Light at a low angle makes worn stamped characters readable.
  • 3Capture the full marking. Include every suffix character. Take several shots if it wraps around the ring.
  • 4Add context shots. The whole bearing, its position on the shaft and the reducer nameplate.
  • 5Label each photo. Name files by shaft and end, e.g. "Output-L".
Close-up of the stamped designation on a bearing ring face, lit from the side
Example: marking photographed with low-angle light, full suffix in frame.

03Substitutes & Technical Changes

No technical change is made without buyer approval. Any alternative to the original NTN execution is marked separately on the quote, so you can review it before deciding.

Will you replace the specified bearing with a different execution without asking?

No. Selection follows the NTN designation and execution in the equipment's original specification.

Any change to the specification needs the buyer's approval before the order goes ahead.

How are alternative parts shown on the quotation?

Alternatives are listed as separate, clearly marked lines, never merged into the original line.

Tell us in your enquiry whether you will consider marked alternatives at all. If not, we quote only the original executions.

Who on our side should review a proposed change?

Usually the reliability engineer, who reviews operating conditions and any departure from the original specification.

The technical buyer then checks that the designation, set quantities and marked alternatives match the approved list.

04Quotation & Product Documents

Every quote from oemntn.com is written and itemised, so each line can be checked against your overhaul list before you order.

What does a written quotation include?

It includes the elements below, so nothing has to be confirmed verbally.

ElementWhat it confirms
Product designationFull NTN designation per line
QuantityPieces or sets per line
Price & currencyUnit price and quoting currency
AvailabilitySupply status of each item
Estimated lead timeExpected time to dispatch
Quote validityHow long the offer stands
Shipping / tax termsApplicable transport or tax conditions
Can you provide certificates or test reports?

Ask when you request the quote which product documents can actually be supplied for your items. We confirm what is available per order rather than promising a standard document pack.

If your project needs specific paperwork, list it in the enquiry so it can be checked before you order.

What should we check before placing the order?

Check specifications, quantities, delivery details, payment arrangement and commercial terms against your approved list.

Once those match, confirm the order.

Have the full parts list ready?

Send it in one message: reducer model, shaft positions, suffixes, paired sets and quantities.

Send List on WhatsApp Email Your Parts Drawing

05Shipping & Receiving

The shipping method, dispatch schedule and transport documents are confirmed with you before dispatch. At delivery, three checks catch most problems while they are still easy to fix.

How should we check the goods on arrival?

  1. 1

    Check the labels

    Compare the product labels with the designations on your order, including suffixes.

  2. 2

    Count the quantities

    Count pieces and complete paired sets per line against the order.

  3. 3

    Inspect the condition

    Look over packaging and products for visible damage before storage or fitting.

Found a discrepancy? Contact us with the order number and photos of the labels, quantities or condition issue.

Do you ship worldwide from Hong Kong?

Yes. oemntn.com is registered in Hong Kong and supplies customers globally.

Give the destination country and postcode in your enquiry so transport terms can be quoted accurately.

Warehouse staff checking bearing box labels against a delivery note
Receiving check: labels, quantity, condition.

Didn't find your answer?

Send your full overhaul list and get a written quote

Include the reducer model, shaft positions, NTN suffixes, paired arrangements, the parts drawing, quantities, destination and required date. Unclear markings? Add photos.

oemntn.com · NTN authorized distributor · Room 2009-2010, Gala Place, No.86 Dundas Street, Mongkok, Kowloon, Hong Kong

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