SNOWEST JANUARY 2017 23
a CVT system. The stationary sheave
of a driven clutch is on the outside
opposite the stationary sheave of the
drive clutch so that the belt stays in
alignment throughout the shift. In a
driven clutch, the spring acts to keep
the clutch shut rather than open. The
driven clutch spring also acts to push
the belt out on the diameter of the
clutch or shift to a lower gear when
you let off the throttle. This is called
backshift.
HELIX
The load sensing part of the driven
clutch is the helix. If a driven clutch
didn't have a helix, you would hit the
throttle and the belt would go straight
to the bottom of the driven clutch
(high gear). The helix resists upshift as
more torque is applied to the belt. The
angle of the helix at the beginning of
the shift (low gear) might be very dif-
ferent than the angle needed at the end
(high gear).
Helixes ride on sliding buttons or
on a roller. The race sleds from Polaris,
Arctic Cat and Ski-Doo all use the
Team TSS-04 clutch, a roller design.
The QRS from Ski-Doo and the BOSS
secondary from Arctic Cat are also
roller designs. Yamaha introduced the
YSRC roller version of its driven clutch
for the Sidewinder this year.
Another unique snowmobile driven
clutch design is the Team Tied clutch.
You may have seen a Tied clutch design
on a Polaris RZR. This clutch oper-
ates by opening and closing the mov-
able sheave in parallel to the stationary
sheave, unlike non-tied designs that
rotate the sheaves relative to each other.
This design had less belt scrub that pro-
duces heat. In addition, all of the torque
goes through the helix in a tied design.
This allows more precise tuning. d
(Dohrer is in the research and devel-
opment department at Venom Products.
For more information, visit www.venom-
products.com or call 218-844-3283.)
W W W . P O W E R C O M M A N D E R . C O M
F U E L I N J E C T I O N M O D U L E
SUPERIOR OPTIONS - PRECISE CONTROLS
A R C T I C C A T • P O L A R I S • S K I - D O O • Y A M A H A
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