What Are Ball Bearings?

July 13, 2015

There are a handful of mechanical devices within our technically advanced civilization that have justifiably earned a place of prominence. The ball bearing is one such component, one that we boldly declare as a key reason the industrial evolution took place. Without ball bearings, where would locomotives and the prime movers that drive steel mills and hydro-electric generators be today? Anything with a shaft and rotational momentum would be fused to the surrounding assembly due to the heat generated by friction. Having established the worthiness of the ball bearing amongst its mechanical cousins, let’s drag this shy mechanical enabler out of the shadows.

The visionary engineers of the last 150 years tend to reserve a spotlight for massive shafts and axles. Everything from the largest diesel generator to the most unassuming bicycle depends on this rotational force and those shafts, but the ball bearing is what makes this movement possible. It allows external motionlessness to combine with inner radial movement. Friction would naturally occur when these two disparate states met, a phenomenal amount of heat generated by one metal part moving at speed across another, but the rings of the ball bearing have a third component, a friction-reducing stack of parts that act as the grease between the rings. The slip-sliding rings never make contact. Instead, a series of hardened steel or ceramic balls fill the space between the rings. This spherical grouping edges the outlines of the inner ring of steel and sits beneath the outer ring, thus forming the midpoint of a radial sandwich.

The applications of ball bearings are numerous. If there’s a wheel or axle out there in use, then a ball bearing is in all likelihood being used to cancel friction. Inner rings turn with the shaft and outer rings stay immobile, shunting the radial force through the bearings. Roller skates adopt this outline, as do skate boards, all manner of vehicles and any kind of machinery that depends on radial motion. This includes pumps and gearboxes, huge generator drive shafts and tiny timepiece mechanisms.
In fact, ball bearings are still the essential rolling-element mechanisms of choice, with many versions of the component adopting the same shape as yesteryear. The biggest difference comes from lubrication technology and the graded steel alloys used to manufacture the part, especially when the design application is a heavy-duty one.

Let’s conclude with a few terms that any ball bearing enthusiast should recognize. The actual ball bearings are held within a central cage, the design of which is key in ensuring the bearings can move freely. The inner ring is known as the “inner race” and the outer ring, the critical part that’s attached to a motionless housing, is technically labelled as the “outer race.”

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