What shape are ball bearings? They are shaped like a ball, as everyone knows, right?
The funny thing
about what everyone knows is that everyone can be wrong. For instance, everybody thinks that the
America's Cup is an ocean-sailing race, and yet the Swiss managed to win the
Cup. For those readers who are
geographically-challenged, Switzerland is a land-locked country comprised
entirely of mountains.
What does this have
to do with ball bearings. Very little, I
suspect, but balls have very little to do with ball bearings, either. Ball bearings look more like hula hoops. But don't try using them for that – you will
find them inconveniently heavy and painfully small.
So, what are those
stunted metal tube donuts called ball bearings for anyway? Are they used as a spare wheel? Do they hold in evil shop-floor spirits? No, they help things move more efficiently. In a demonstration of bearing usage, three
ladies pulled a locomotive (It was just a demonstration, not a career
development).
Many bearings look
very similar, whether they are ball bearings, roller bearings or other
bearings. What?! Other bearings?
What is a ball bearing, anyway?
Ball bearings are
formed with an outer ring, an inner ring, a cage or a retainer inside, and a
rolling element inside, typically a ball (which is why they are called ball
bearings). Roller bearings are formed
using a roller instead of a ball, which is why they are called roller bearings
(Yes, finally something that makes sense!).
Other bearings look just like metal tubes, called plain bearings or bush
bearings. They look like sawed off pipe
or tube.
The principle of
bearings is the same principle behind the wheel: things move better by rolling
than by sliding. They are called
"bearings" because they bear the weight of the object, such as an
inline skate or the head of dentist's drill, allowing the object to glide over
them with incredible ease and speed.
Unlike wheels, they don't turn on an axel; they turn on themselves.
The balls or
rollers spin on themselves inside the bearing, reducing friction for the
machine parts attached to them. It's
much neater than using a bucket of oil, especially in dental equipment, and
significantly more reliable than hamsters on a wheel.
Once upon a time,
all bearings were metal – like a metal tube or pipe with metal balls stuck
inside. These days, more and more are
made of ceramic or even plastic (like everything else in this world!).
If you are still
confused about why ball bearings are not shaped like balls, just remember that
you drive on a parkway and park on a driveway.
And you can even try sailing your sea-craft through the Swiss Alps. But don't try playing a game of one-on one basket
bearing.
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