ELNA Supermatic Service Manual page 35

Upper Tension Device
How it works
The Tension Discs and Check Spring are assembled on the
Upper Tension Bar which passes through the upper tension
plate and is pinned against the Tension Regulator Spring.
The Tension Regulator Pin passes through a bushing attached
to the upper tension plate and presses against the Tension
Regulator Spring.
As the pressure from the Tension Regulator Pin on the
Tension Regulator Spring increases, the Tension Discs are
squeezed together tighter.
The Separating Disc between Tension Discs allows the use of
2 threads (one on either side) for twin needle sewing.
To soften the sharp tugs of the Thread Take‐up Lever on the
thread, the upper thread tension device is equipped with a
Check Spring, which considerably reduces the danger of the
thread breaking.
The numbered Tension Regulator Dial (‐0 to 9+)
has a spiral ramp where the Tension Regulator
Pin rides.
As the dial is turned from (0) towards (9), the
ramp pushes the Tension Regulator Pin which
pushes on the Upper Tension Spring, this
squeezes the Tension Discs together.
When The Presser Foot Lever is raised, it pushes
the Release Pin out. The Release Pin pushes on
the Upper Tension Bar and releases the spring
tension on the Tension Discs, allowing the top
thread to pull freely through the Tension Discs
for threading the machine or removing the
material being sewn.
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