NTNHeavy-Series Angular Contact Ball Bearing 40 x 110 x 27 mm, Single Row, ABEC 5, Phenolic Cage

Product Description

What this part is

A single row angular contact ball bearing in the heavy 7408 envelope: 40 mm bore, 110 mm outside diameter, 27 mm width. It is ground to P5, which is ABEC 5, and it runs a phenolic cage. One row, one direction of thrust.

Decoding the designation

7408 is the ISO angular contact base number in the heavy 74xx series, 40x110x27 mm.

T1 denotes a phenolic (laminated fabric) cage.

P5 is the NTN precision class corresponding to ABEC 5. NTN’s B5 code, seen in the cross-references, denotes the same ABEC 5 grade.

Why the heavy 74xx section exists

A 7408 is not a 7208. Both sit on a 40 mm shaft, but the 7208 is 80 mm across and 18 mm wide while the 7408 is 110 mm across and 27 mm wide. That extra 30 mm of outside diameter is section thickness: bigger balls, deeper raceways and much heavier rings. Capacity in a ball bearing scales hard with ball diameter, so the 74xx carries substantially more thrust and radial load and is markedly stiffer than a light series bearing on the same bore.

The trade is speed and space. The larger balls have a higher surface velocity at a given shaft speed and the heavier rings and cage generate more heat, so a 74xx will not spin as fast as a 72xx or 79xx on the same shaft. It suits designs governed by load and rigidity rather than speed. A 7208 is not a substitute for a 7408 on the strength of a shared bore; the housing bore is different and so is the load capability.

What these specs mean in practice

The phenolic cage is unusual on a heavy series bearing. Laminated fabric is far lighter than the brass cage often fitted to this section, so cage inertia and pocket friction stay lower and the bearing tolerates higher speed than its section would otherwise allow. Phenolic also absorbs oil, which helps through start-up and marginal lubrication. The limit is temperature: sustained operation should stay below roughly 120 °C.

ABEC 5 is a genuine precision grade but a step below the ABEC 7 used in high-speed grinding spindles. It suits duty that is heavy load and moderate speed, where the cost and the seat-machining demands of ABEC 7 are not justified.

Mounting data

Single row, single direction of thrust. There is no duplex or universal grind code in this designation, so the bearing is not universally ground and carries no built-in preload.

Quantity and configuration

One bearing, single row.

Interchange guidance

The same bearing appears in NTN literature and in the trade as 7408 T1 P5, 7408 B5 and 7408T1B5, the B5 and P5 codes both meaning ABEC 5. Other manufacturers offer the 7408 envelope at 40x110x27 mm, but cage material, contact angle and precision class should be confirmed before substituting, and the replacement must be a 74xx heavy series part rather than a light series bearing with a similar-looking number.