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BASIC CLUTCH
The clutch consists basically of a spring which is wrapped with a slight interference
fit around two adjacent drums -- an input drum and an output drum. Rotation
in one direction causes the spring to wrap down and drive. When the rotation
is reversed, the spring loosens its grip and slips. |
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OVERRUNNING CLUTCH
In its simplest form the spring clutch functions as an overrunning clutch. It
drives one way and slips upon reversal. the output member is free to overrun
the input member. It can also be used for one way indexing and backstopping. |
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ON-OFF CLUTCH
By the addition of a radial tang on the input end of the spring, the clutch can
be controlled. Normally the input hub rotates continuously and drives the output
hub. When the tang is arrested, the spring tends to unwrap and uncouples the
clutch. The output member may coast to a stop depending upon the inertia of
the driven load. For convenience, the spring is surrounded by a release collar
which has a projecting lug on its outer diameter and an inner slot which engages
the spring tang. |
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SINGLE/FRACTIONAL REVOLUTION CLUTCH
The single revolution type clutch is constructed the same except for the addition
of a second spring tang which is anchored to the output member. This assures
that the output always stops in the same angular position when the release
collar is stopped. Multiple stop lugs added to the release collar result in
a fractional revolution clutch. |
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SINGLE/FRACTIONAL REVOLUTION
WITH ADJUSTING COLLAR
In some applications it is desirable to precisely adjust the angular stopping
position of the output hub after installation in a piece of equipment. This is
accomplished by the use of our patented clamp type adjusting collar* which securely
clamps the output end of the spring to the output hub. When the clamp screw is
loosened, the output hub may be rotated relative to the lug on the release collar.
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SINGLE/FRACTIONAL REVOLUTION
WITH OVER-TRAVEL STOP
This feature provides an adjustable, positive stop in applications involving
higher inertia loads and where the output member tends to over-travel the arrested
release collar possibly damaging the spring. The clamp type adjusting collar*
also serves as a positive over-travel stop. A pin projecting from the release
collar extends into a radial slot in the adjusting collar. When the release collar
is stopped, the output hub continues to rotate through a few degrees of arc until
the radial slot face strikes the stop pin. Both the degrees of over-travel and
the output stopping position can be adjusted simultaneously after installation
in a piece of equipment. |
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*U.S. Patent 3,835,972
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Fractional
Revolution
