NHBBME-1109DLSuper-Precision Angular Contact Ball Bearing Matched Duplex Pair, 45 x 75 x 16 mm, Light Preload, Phenolic Cage, 2 Pieces per Set

Product Description

What this part is

A factory matched duplex pair of super precision angular contact ball bearings, supplied as one set of two. Each bearing measures 45 mm bore, 75 mm outside diameter and 16 mm width, corresponding to the ISO 7009 envelope. Both rings are engraved ME-1109DL and THRUST NHBB USA, and both carry the asterisk match mark and a scribed match line across the outside diameter that identify them as a ground-together set.

Decoding the designation

NHBB — New Hampshire Ball Bearings.
ME- — NHBB’s precision spindle bearing series prefix.
1109 — NHBB size code corresponding to the 7009 envelope, 45x75x16 mm.
DL — duplex, light preload.
THRUST engraved on the outer ring face — the thrust direction marking, telling you which way the bearing takes axial load.

Quantity and configuration

This listing is one lot containing two bearings. That is deliberate and it is not an inventory discrepancy: DL means duplex, and NHBB ground these two rings as a matched set, so they are inventoried and sold as a single unit. Our photographs confirm the count directly. The bearings arrived stacked in one sealed bag under a single paper band marked NHBB ME1109DL, and a second photograph shows them side by side, both engraved ME-1109DL, each with an asterisk match mark and a scribed V line that lines up across the pair.

The practical consequence is that these two should stay together. Splitting a matched pair and mating either half with a bearing from a different set defeats the point of the grind, because the preload the set produces depends on the two rings having been finished as a couple. If you need only one bearing, this is not the right listing.

Why a duplex universal grind is worth paying for:
On an ordinary pair of precision bearings, setting preload is a metrology job: you measure, then shim or grind a spacer until the clamped stack produces the axial stiffness the design calls for. A universally ground duplex set removes that step. The ring faces are finished so that clamping the two together back-to-back, face-to-face or in tandem produces the specified light preload on its own. You get a repeatable, documented preload with a torque wrench instead of a bench full of gauges, and the next rebuild reproduces it.

Preload class has to match across the set, which is why DL on both rings matters. Mixing a light preload bearing with a medium or heavy one loads the two rows unevenly: one row carries more than its share, runs hotter, and fails first. Light preload itself is the choice for speed and thermal stability, trading some axial rigidity for lower friction and less heat generation than a medium or heavy setting.

What these specs mean in practice

The cages are phenolic, visible in the photographs as the dark reddish-brown rings between the raceways. This is a genuine selling specification and it is usually missing from the paperwork. Laminated fabric is far lighter than steel or brass, so cage inertia and ball pocket friction stay low, and phenolic absorbs oil, which carries the bearing through start-up and marginal lubrication. The constraint is temperature: keep sustained running below roughly 120 °C and avoid aggressive solvents when cleaning.

The 16 mm width at 45 mm bore puts this in the light 70xx section, which is the conventional choice for a high-speed spindle where the radial envelope is constrained and loads are moderate.

Published ratings and mounting data

NHBB does not publish dynamic (Cr) or static (C0r) load ratings, a contact angle or a limiting speed against the ME-1109DL designation in any source reachable today. This is a legacy precision spindle designation and its data existed only in printed catalogues. We have deliberately left those fields blank rather than borrow figures from a generic 7009 or from another manufacturer, because contact angle, cage material and preload class all move the numbers and a borrowed rating on a spindle bearing is worse than an honest gap. If your calculation depends on certified values, ask NHBB to pull the record for ME-1109DL.

Fitting notes

Keep the pair banded and bagged until the moment of assembly and note the orientation before you separate them. Align the asterisk match marks and the scribed line as ground; that alignment orients the high points of the rings the way the factory intended and is part of what makes the running accuracy repeatable. Observe the engraved THRUST marking so the axial load closes the contact rather than trying to separate the rings. Press only on the ring being fitted, never through the balls, and finish shaft and housing seats to at least the same tolerance class as the bearings, otherwise the precision is lost before the spindle turns.

Interchange guidance

The metric equivalent designation for this size and configuration is 7009-C-TPA-P4-DUL, a 45x75x16 mm super precision angular contact bearing with a phenolic cage, P4 precision and duplex light preload. Any maker’s 7009 in a universally ground light preload duplex configuration is worth evaluating, but confirm contact angle, cage material and preload class before substituting, and buy a matched pair rather than two singles. Matching the boundary dimensions alone is never sufficient on a spindle bearing.