What does 21 jewels mean in an automatic wrist watch?

Question

Before quartz and atomic wrist watches, there were automatics. What is the function of jewels in these watches????

Answer 1

Reducing friction is an extremely important goal in watchmaking. Jewels have two important properties that help reduce friction. First, they can be made to be very smooth, and therefore they let the metal parts slide easily. Secondly, they are very hard and therefore don't wear down very quickly. The gears in a watch are carefully designed so that the teeth roll on each other, rather than sliding. If the axle of a gear wears away the hole that it sit in, the gear will shift. That means the teeth will no longer roll on each other and therefore friction will be increased.

Much more info at the link below.

Answer 2

Bulova 21 Jewels Automatic

Answer 3

Bulova Automatic 21 Jewels

Answer 4

This Site Might Help You.

RE:
What does 21 jewels mean in an automatic wrist watch?
Before quartz and atomic wrist watches, there were automatics. What is the function of jewels in these watches????

Answer 5

Hi. The jewels were used for bearing surfaces for the gears, automatic or not.

Answer 6

watches can have metal on metal bearings, or bearings where a jewel is used to isolate the metal to metal contact - classically this has been a preferred way to reduce wear, but modern metallurgy makes it kind of academic

Answer 7

I think jewel is so hard that it can be pointed each other without reducing their component..

Answer 8

Sounds interesting

Answer 9

You raise some good points in your question.