Two bearing families answer ninety percent of industrial RFQs: deep groove ball bearings and angular contact bearings. Buyers rarely need more than these two - but quoting the wrong one for the load direction is the most common error we see in drawings. Here is the one-page version.

The Load Direction Rule


Deep groove (our 608-2RS stock line) carries radial loads - force perpendicular to the shaft. Think of a wheel, an idler pulley, a fan spindle. It also takes a small amount of axial load in both directions as a bonus, which is why it is the default choice when in doubt.

Angular contact carries combined loads where axial force dominates - a leadscrew, a pump shaft with hydraulic thrust, a spindle that pushes. The raceways are offset so the balls contact at an angle (15, 25 or 40 degrees). The catch: one direction only. Pair them back-to-back or face-to-face (DF/DB arrangements) when the shaft pushes both ways.

The rule of thumb: if the axial load is more than about a quarter of the radial load, you probably want angular contact, not an oversized deep groove.

Seals: 2RS, ZZ, or Open


  • 2RS (double rubber seal) - the default for maintenance buyers. Greased for life, survives washdown dust and splashes, slightly lower speed rating. Our stock bearings ship 2RS with lithium grease rated -30 to +120 C.
  • ZZ (metal shields) - higher speed, no contact friction, but not sealed against fine dust or moisture. For clean, dry, fast applications - spindles inside enclosures.
  • Open - when the bearing runs in an oil bath or gets regreased by the machine's central system. Buying open bearings for a dusty environment to "save money" costs more in downtime than the bearing ever cost.

The Speed Check Nobody Runs


Every bearing has a grease speed limit ( ours 608-2RS: about 32,000 rpm) and oil limit. The mis-specification we catch most: a buyer quotes a 2RS bearing for a 40,000 rpm spindle because the catalog's "limiting speed" was the oil value. If your shaft speed is within 20% of the grease limit, switch to ZZ or oil lubrication - or step up a precision class (ABEC-5) which raises the limit and cuts vibration.

ABEC Classes: What You Actually Pay For


ABEC-3 is the standard industrial class - more than enough for wheels, conveyors, fans. ABEC-5 buys tighter runout for spindles and high-speed tooling; ABEC-7 and above belong in grinding spindles and gyroscopes, not general machinery. Paying for ABEC-7 in a conveyor is money spent on nothing the application can feel.

Sourcing Notes


When you send an RFQ: state the radial and axial loads (or the application - "bench grinder wheel, 3000 rpm" is enough for us to derive them), the environment (dry / dusty / washed down), and the target life in hours. A 1-2-3 setup block-grade answer needs those three inputs; without them any supplier is guessing, and the cheapest guess usually becomes your downtime.