Martin --

A very good description, thanks for providing it!

As an experiment, we attempted to use the differential that came in the
same heavy duty pickup truck that furnished our 454 c.i. engine. This
unit was mounted as you would expect between the twin drums and one drum
was braked by its respective master cylinder brake lever, leaving the
power to be applied to the opposite drum. This arrangement went fine for
about an half-dozen launches, when the diff over-heated and eventually
gave up the ghost.

Thus we learned that the differential feature as we were using it would
have to be disabled and a couple of dog clutches would have to be
devised in order to turn our winch into a true double-drum unit.

BJ



Martin Gregorie wrote:

On Fri, 31 Oct 2003 16:10:15 -0600, Bob Johnson
wrote:

Antti --

I really appreciate that photo. It appears to be a twin drum machine
with right angle drives to each drum. Do you know how the builders got
that power to go around the corner, that is, does it use a conventional
automotive-type differential, angle gears, or what?

Supacats, anyway, have a massive purpose designed gearbox mounted
between the twin drums. It is driven via a fluid clutch and drives the
two outputs via dog clutches as well as the oscillating pay-on arms.
There are three separate brake systems (one on each drum, plus one on
the output side of the fluid clutch). The drum brakes have independent
hydraulic circuits connected to separate brake levers. The input brake
and the output dog clutches are mechanically interconnected on a
single lever - it moves sideways to select left, right or no drum and
back to apply the brake on the clutch output. In addition there are
payout brake levers that apply light pressure to the drum calipers
while the cable is being pulled out.

The separate throttle connects to the Deutz diesel via a profiled cam
that gives a more or less linear power response. By that I mean that
more or less equal movements give similar power increments over the
whole range. It makes smooth launches a lot easier.

Safety: pulling rather than pushing the throttle cuts the motor. Both
guillotines are operated simultaneously from an in-cab hydraulic
circuit or, if this fails, each can be fired mechanically from
outside. A flashing yellow light on top the cap operates when the
winch is running and in gear. Nobody touches either cable when its
flashing.

Climate control: there is a diesel burning heater for winter and the
sliding doors open in summer.

HTH

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :