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Tim Gant says:
The chassis is very simple, with
closely space bush wheels (I used brass ones as
they have a smooth rim) forming the bearings wich
rest on the axles holding the disc wheels. This and
the hard plastic of the Prima discs provides for
exceptionally low rolling resistance.
The main axles carry Prima discs
which are mounted on the 3/8" bosses of small bush
wheels (which are locked on the axles with short
grub screws), offset by a plastic-Meccano rubber
washer (you can just see them between the flat of
the bush wheel and the inner face of the Prima
discs). They are held in place using pulleys with
tyres pressing against the discs outer surface by
way of springs from the Space 2501 rocket
launchers. They appear rather ellaborate and I'm
sure there is a simpler way of doing this, but
these were the pieces that fell to hand the night
before the WLMS meeting.
The winding drum utilises small
plastic Meccano spacers (from the recent French
outfits), but you can get it to run with the string
wound directly on the axle, assuming you wind it
thick at the starting point, to allow a little
extra torque to overcome the initial
friction.
The frame is made up of 11-1/2"
axles rods held in rod sockets on the chassis and
then butted end to end in rod connectors tapering
in gently at about 6' up to rod and strip
connectors that are screwed to the strips that make
up the simple pulley frame at the top. I used a few
narrow strips, and clock-kit rods about mid way up
to provide some bracing (otherwise it really is too
flimsy).
The weight is shown also - and
that too had to be made from Meccano.
The chassis should really have a
few plastic plates across it to catch the weight
once the string has fully unwound from the driven
axle.
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