Winter Challenge 2001, Independent control of the props.


David Chapman

We mentions this every so often, I'm determined to have a go this winter !

Some years ago I drove a very modified Amphicar with a hydraulic
transmission, this allowed the props to be switched in and out
independently, it was amazing, would almost turn in it's own length, made me
think I was in a proper boat !

I see two ways to do this on our cars without too much work, split the
exisiting rod that goes into the water trannie along it's length so it's two
half round pieces that slide seperately, the bracket inside the trannie with
the selector forks on would then have to be cut in half and welded to each
rod - that would be tricky as it's different metals but can't see any other
way to fasten, would then have to modify linkage so 2 levers next to
gearshift or use some sort of solenoid mechanism near where rod(s) go into
trannie. What I don't like about this solution is it means getting inside
the water trannie - and if you got it wrong and the gears broke or something
fell off it would be a mess !

Plan b would be to use some sort of low profile dog clutch on the prop
shafts, immediately where it comes out of trannie, prop shafts would need to
be shortened. The clutch, (obviously would need one each side) doesn't need
to slip so could be very simple, but it would spin at up to 1000rpm with the
shaft, and would need some way to disengage - a fork sort of thing
controlled by cables ? My lawnmower (!) has a similar system but that's
maybe 2 HP not 43 HP, has anyone seen something on some other vehicle that
could be adapted ? What about on a small ATV or even a boat - or motorcycle
? Or maybe modify that flange somehow but then we are probably back inside
the trannie again.

Plan c is similar, except thought is to cut the propshaft maybe 1/3rd of way
along and have it running in some sort of sleeve - this might work better,
lighter and less balance problems, but can't think of an easy way to

So - come on Amphi Engineers (including you Germans !) there must be a way
to do this. Amphicars will soon all have an important birthday, the big 4
0, let's give them a treat and make them feel young again !

David Chapman - (60 feet right 90 feet left is no longer good enough !)