Excelsior Park JB4

	Brand:	Excelsior Park
	Family:	Excelsior Park JB4 Family
	Height:
	Jewels:	17
	Reserve:	hours
	Frequency:	18,000 A/h
	Winding:	Hand winding
	Diameter:	31.60 mm (14 ligne)
	Complications:	2-Button, 8-Column Chronograph, Chronograph, Column Wheel Chronograph, Monopusher Chronograph
	Hands:	45 Minute Chronograph Hand at 3:00, Central 60 Second Chronograph Hand, Central Hour Hand, Central Minute Hand, Small Seconds Hand at 9:00

Distinguishing Technical Characteristics
Hand-Winding Counter-Clockwise Balance Cock Screwed Balance Indexed Regulator 8-Column Chronograph Balance at 6:00 Column Wheel at 12:00
Production: 1928 –
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

Cal. JB4 is a round 14 ligne chronograph movement produced by Excelsior Park from 1928 through the 1960s. It is a hand-winding movement with 30 or 45 minute counters at 3:00 on the dial. The movement measures 31.60 mm in diameter and served as the base for a family of movements used by many watchmakers.

All Excelsior Park Cal. JB4 family movements are instantly recognizable thanks to the distinctive U-shaped cock that supports the chronograph wheels. Nearly every other chronograph uses a Y- or wishbone shaped cock or bridge. The overall design of the movement is also “reversed” from many other chronographs, with the rabbit-shaped hammer falling on the crown side and a counter-clockwise balance cock. Although not a finely-finished movement, it is high in specification with a Breguet spiral hairspring, screwed balance, and machined springs. The chronograph minutes recorder is equipped with a “sautoir” (jumping mechanism).

One version, Cal. JB4-24h includes two novel features: A central 24 hour hand used for orienteering and a “seconds corrector”, allowing manual adjustment of the running seconds hand using a crown at 9:00.

Excelsior Park chronograph movements were used by Gallet, Zenith, and Girard-Perregaux as well as in-house by Excelsior Park and Moeris. These were roughly similar apart from their finishing and the specification of a mobile stud carrier by some brands. The “JB” stands for Jeanneret-Brehm, the name of the founder of the Excelsior Park factory.