NSKHR33010JDBP5Matched Back-to-Back (DB) Tapered Roller Bearing Pair with Ground Spacer, 50 mm Bore x 80 mm Outside Diameter, P5 / ABEC 5 Precision, Two Cones + Two Cups + One Spacer per Set

Product Description

What this part is

A factory-matched pair of metric single-row tapered roller bearings, supplied as a back-to-back DB set with a ground spacer ring. Bore is 50 mm, outside diameter 80 mm. This is not a single bearing and it is not a random pair of two bearings out of a bin: the rings and the spacer are ground together as a unit to produce a specified preload when they are clamped up, and the set only performs as specified if it stays together.

Photographs confirm the composition. Each set consists of five pieces: two cones (inner rings with roller and cage assemblies), two cups (outer rings) and one ground spacer ring. Ring markings read NSK HR 33010J with the DBP5 pairing mark; the carton is labelled HR33010JDBP5+KL7CP45, lot 406, and the original NSK inspection slip is present.

Decoding the order code

HR — NSK’s high-capacity tapered roller design. Larger and longer rollers in the same envelope than the base metric series, so the load rating rises without a dimensional change.33010 — ISO metric tapered roller size designation. The 330 prefix identifies the double-row-width dimension series and the final digits give the bore code; 33010 is a 50 mm bore, 80 mm outside diameter size.J — pressed steel cage.DB — back-to-back arrangement, sometimes written face-to-face’s opposite. The two cup backfaces sit together, so the effective load lines diverge outward.P5 — ISO precision class 5, equivalent to ABEC 5. Two grades tighter than standard P0/ABEC 1 on bore, outside diameter, and critically on radial and axial runout.+KL7CP45 — the matched spacer element supplied with the pair. The plus sign in NSK nomenclature denotes an accompanying component ground to suit; the C-class digits identify the preload/clearance value the set was matched to.

What these specs mean in practice

The DB arrangement is the reason people specify a pair rather than one bearing. Mounted back-to-back, the two rows’ load lines spread apart as they travel outward, which gives the pair a wide effective support span even though the two bearings are physically adjacent. That translates into real moment stiffness — the ability to resist a shaft trying to tilt — from a single short bearing position. Face-to-face (DF) pairs do the opposite, converging their load lines to a narrow span, which is what you want when you need the assembly to tolerate misalignment instead of resisting it. Fitting a DB set where a DF set belongs, or vice versa, changes the stiffness of the machine, not just the bearing.

P5 precision is about runout, not just size. A tighter class means the raceways are more concentric with the bore, so a shaft mounted in these bearings turns with less radial and axial wander at the working end. That is why P5 tapered pairs turn up on machine tool spindles, rotary tables, worm gear reducers and precision indexing heads, where a few microns of runout at the bearing becomes a visible dimensional error on the workpiece.

The spacer is the whole point of a matched set. Tapered roller bearings have no built-in clearance — the working preload is set entirely by how far the two rows are pushed together on assembly. Get that wrong and there are two failure modes waiting: too loose and the rollers skid instead of rolling, which polishes and then beats out the raceway, and the spindle loses stiffness; too tight and the friction generates heat faster than the lubricant can carry it away, the rings grow thermally, the preload rises further, and the bearing destroys itself in a runaway within hours. A matched set with a ground spacer means the correct preload is achieved simply by clamping the stack solid, with no measurement and no guessing on the bench.

Quantity and configuration

Priced and sold per matched set. Each set is five pieces: two cones, two cups, one ground spacer. Nothing else is included — no lock nut, no housing, no seals, no shim pack.

The two bearings in a set must not be split up and must not be swapped between sets, and the cups must not be rotated between positions. Once the matched grinding relationship is broken the preload figure the set was built to no longer applies and you are back to setting it by hand. Keep each set’s five pieces together and keep them clean.

Published dimensional data

Bore d: 50 mmOutside diameter D: 80 mmSingle-row assembled width T for the 33010 metric size: 24 mm (ISO series dimension for this designation)Number of rows per set: 2Cage: pressed steel (J)Precision class: P5 (ISO class 5 / ABEC 5)Arrangement: DB, back-to-back, matched with ground spacerCountry of manufacture: Japan

Load ratings for the HR33010J are not reproduced here because we have not verified them against an NSK-published source for this specific HR high-capacity variant, and the HR design’s ratings are higher than the base 33010 figures — quoting base-series numbers would understate the bearing. Ask us if you need the catalogue figures confirmed before you specify.

Fitting notes

Cone and cup are lapped as a matched design pair. Do not mix rings across part numbers or manufacturers on nominally identical dimensions; the contact angle relationship changes and you get edge loading on the roller ends.

Press each ring on or in by its own face. Never transmit installation force through the rollers — a single blow through a roller leaves a brinell indentation in the raceway, which on a P5 precision bearing shows up immediately as runout and then as a spall.

Housing and shaft fits matter more at P5 than at standard class. A tight class bearing pressed into a sloppy or out-of-round bore simply inherits the bore’s error, and you have paid for precision you will not get. Check bore roundness and shaft diameter before assembly.

Observe the assembly orientation. Back-to-back means the cup backfaces face each other with the spacer between them; reverse the stack and you have built a DF pair with entirely different stiffness and, because the spacer was ground for the DB geometry, an incorrect preload as well.

Interchange guidance

Written variously as HR33010JDBP5+KL7CP45, HR33010J DB P5, HR33010JDB, HR33010J, HR 33010 J, 33010J and 33010. The base ISO size designation 33010 is shared across manufacturers on the 50 x 80 mm envelope, but a matched DB P5 set with a ground spacer is not interchangeable with two loose standard-class single bearings of the same size — the size may match, the precision class and the preset preload will not. Cross-reference by designation and by class together.