Olympus OM-1 Repair Manual page 35

B—14
(7) Second Curtain Operation:
While the shutter is charged, the curtain remains pulled by the Tension
Spring (8599) provided in (8526) in the arrowed direction.
Upon receipt of the signal from the first curtain, (8563) is released and
the second curtain string is wound up onto (8526) by means of the
Tension Spring (8599) and the curtain runs.
At this time, the rotation speed of (8526) is an important factor
determining the exposure time since it relates to the speed of the
second curtain.
8507
(8) Shutter Speed Adjustment:
The exposure time is determined by the curtain speed and the slit width
(interval between the first and the second curtain). When the curtain
speed is fixed, the exposure depends on the slit width. In case of MDS,
the curtain speed is set at 11.7 - 12.1 ms. (for both the first and the
second curtains), and the exposure time is adjusted by various slit
width.
The major part of the mechanism used for this purpose is:
Low Speed 1/1 1/2
1/4 1/8
1/15 1/30
High Speed 1/60 - 1/1000
Large ankle on the governor.
Small ankle on the governor.
Gear only of the governor.
By the shape of (CA8549, Cam)
not using the governor.
http://oIympus.dementia.org/Hardwsirc