The Seiko 6139-7100 series automatic chronograph - like this all-original full serviced example here from early 1976 - gets its nickname, “helmet,” from its highly unique case shape. Seiko placed their movements into multiple highly unique cases, leading to a plethora of out of the ordinary shapes and sizes.
Back in the late 1960's, Heuer and Zenith had taken hold of the entire sports watch industry by racing to become the first to produce an automatic chronograph. It has been widely debated who won, but in the background of this skirmish, Seiko quietly created their own at the same time, beating the Swiss at their own game – the Seiko 6139.
The 6139 was the first chronograph to have a vertical clutch, a feature considered by many to be one of the hallmarks of a superior automatic chronograph movement. The 6139 also features an automatic column wheel timing control, vertical coupling mechanism, and is an integrated chronograph – the first in the world – which means the entire 6139 movement was designed and built to be a chronograph, vice being an automatic movement with a mere timing module added.
With this movement, Seiko set the standard, which was followed by the Swiss watch industries 20 years later. The same movement configuration was adopted by Rolex when it made its own in-house movement for the Daytona in 2000, 30 years after Seiko released the caliber 6139 and 6138.
This 6139 includes a leather strap, green ZULU strap, springbar tool, and Pelican travel case.
1976 Seiko 6139-7100 Helmet Automatic Chronograph
DIAL: Original white dial, with slight patina, with original minute, hour, and black chronograph hands – lume faintly shines. Day/date complication – with Spanish/English variants – at 3 o’clock position works nicely.
CASE: Original 40.5mm x 49mm stainless steel case; crown is recessed.
CRYSTAL: Hardlex crystal, with no scratches.
BAND: This 6139 comes with a light brown leather strap and a premium green "seatbelt" ZULU strap – both great sporty compliments to the inherent vintage nature of this Seiko 6139 helmet.
MOVEMENT: Original Seiko 17-jewel 6139B automatic movement, manufactured in March 1976.
CROWN: Original recessed unsigned stainless steel crown.
CHRONOGRAPH PUSHERS: Chronograph pushers depress with a satisfying click, no stick, and reset as designed to zero with no issue.