NTN7214CDBTAngular Contact Ball Bearing Triplex Set 75x125x24 mm, 15° Contact Angle, DBT Arrangement — Three Bearing Matched Set

Product Description

What this part is

NTN angular contact ball bearings in the 7214 envelope — 75 mm bore, 125 mm outside diameter, 24 mm width per bearing. 15° contact angle, matched and ground as a DBT triplex set.

Decoding the designation

7214 — ISO 72 dimension series, bore code 14, giving a 75 mm bore. The 75 x 125 x 24 mm envelope agrees with the recorded dimensions.
C — in NTN’s scheme, a 15° contact angle.
DBT — a triplex arrangement: three bearings, not two. Two are mounted in tandem facing one direction, and the third faces the other, giving a back-to-back relationship overall.

Three bearings, not two

This is the detail most likely to be misread, so it is worth being blunt about. DBT is a three-bearing set. DB is two, DBT is three. The listing title’s “3 pcs” is consistent with the designation, which is a good internal cross-check on this record.

What the arrangement buys you: the tandem pair shares thrust in the heavily loaded direction, roughly doubling capacity that way, while the single opposing bearing takes the lighter reverse thrust and completes the axial location of the shaft. It is the standard answer for a spindle with a strongly asymmetric thrust load — a drilling or boring spindle pushing hard one way and lightly the other — where a symmetric DB pair would be over-specified in one direction and under-specified in the other.

What these specs mean in practice

15° is the high-speed end of the contact-angle range: the shallow angle keeps the load path near the radial plane, cutting ball centrifugal and gyroscopic effects so the set runs faster and cooler than a 25° or 40° equivalent. The trade is axial stiffness per bearing — which is precisely why a triplex arrangement makes sense here, since stacking bearings recovers the thrust capacity the shallow angle gives away.

Quantity and configuration

Our stock record shows a quantity of 1, which we read as one triplex set of three bearings, consistent with the “3 pcs” in the listing title. Matched sets in surplus are sometimes split, however, so we are not publishing a hard piece count. Contact us before ordering and we will confirm all three bearings are physically present and matched — a triplex set missing a bearing cannot be assembled as intended.

Published ratings and mounting data

Load ratings and limiting speeds are deliberately blank. We could not retrieve NTN’s own published figures for the 7214C, and we have not substituted figures from a different contact angle in the same envelope or from another maker. Note also that a matched set’s effective capacity is not simply the single-bearing rating multiplied by three — load sharing between rows depends on the arrangement. Contact NTN or an authorised distributor with the full designation if a certified rating is required.

Fitting notes

Orientation is everything on a triplex set. Observe the ring markings and the match marks; the two tandem bearings must face the same way and the third must oppose them. Getting the order or orientation wrong changes the set from DBT into something else entirely and destroys the preload scheme. Never shim, lap or regrind the ground faces. Press only on the ring being fitted, never through the balls, and clamp the whole stack fully — a partially clamped matched set carries no preload.

Interchange guidance

ISO base number 7214. Contact-angle letters differ by maker: NTN and Timken read C as 15°; NSK reads C as 15° but A5 as 25° and A as 30°; SKF reads AC as 25°; Koyo reads B as 40°. Confirm the scheme before treating a number as equivalent, and match the arrangement code as well — a DB pair will not substitute for a DBT triplex.