Imagine making a device that won’t ever need charged or a new battery. What would it look like? What would it do?

That’s exactly the thought behind automatic watches.
The self-winding timepieces keep working through everyday use and the wearer’s natural motion.
A bumper movement is a type of self-winding, automatic movement.
However, unlike a modern automatic, which has the rotor spins a full 360 degrees, a bumper moves back and forth at about 120 degrees.

It does this by bumping off a pair of springs on opposite sides of the watch.
The bumper movement can date its history back to the 1920s and English watchmaker John Harwood.
He came up with the idea when observing children playing on a see-saw.
He then began to think of the basic design of a “self-winding mechanism.”
Using accumulated kinetic energy to tension the spring of a wristwatch, a series of experiments by Harwood culminated in the first prototype of a self-winding wristwatch that was created from a discarded pocket watch.

There was no winding crown and the hands were set by rotating a milled bezel, which was also used to wind the mechanism.

A red dot, which appeared in the dial aperture above the 6 showed that the mechanism was running.
One of the rarest examples of a collectible Omega is the Seamaster “Bumper” model from 1950.
The first Seamaster, introduced in 1948 and is still in production today, achieved increasing fame after it was selected in 1995 to be the watch James Bond wears on the big screen.
Have a question about watch repair or something watch-related you think only the Watch Doctor can answer? Leave a question in the comments of this blog and it may be answered in a future blog post. (Don’t worry, we aren’t ignoring last week’s questions.)
Mark Sirianni
25 Fraley St.
Kane, PA. 16735
watchdoctorpa@gmail.com
1-814-558-4818 Cell
1-814-837-9435
9 Comments
Greg Millard
Super info – had never heard of this config, thks Greg M
Jay A.
Thanks Mark ,As a fan of Omega seamasters, and other mid-century watches, I always find your blog very interesting.
Johnny
Great info, I have never heard of this before.
Mark Morgan
Always great information Thank you
Salvatore Lobosco
Great preview mark I have 3 1950 seamaster 351 cal. 1950 automatic, 1944 .all keep good time love them all
Robert Brown
I assume a Tutor submariner has a bumper design. I’ve had trouble with mine not ‘bumping.’
Joe Price
Thanx Mark – Great (interesting) watch information – as usual. I’ve forward your articles to many friends – all have thanked me. ???; Is this “bumper automatic” rewinder similar to that on my 35 year old Rolex Datejust? Being a Senior who moves less these days (especially with our Northern NY winters) – my Rolex has to be hand-wound several times a year. Would the Omega Seamaster resolve these lack of activity periods – winding issues?
Charles R Alford
Joe Price should do what I do: get a job! I have no problem with my 50 year old Datejust. Take my advice, Brenda will be grateful.
Cory Rubino
Very interesting information. Great articles as always. Love my Omega’s and would like a bumper Seamaster for my collection.