Alec Cameron said the following to MIKE ROSS on the subject of
Engine Design (07 Oct 97  19:10:06)
 AC> Hi Mike
 AC> On (04 Oct 97) MIKE ROSS wrote to Alec Cameron...
 AC> Uncontested 85 years you say- makes 1912. I don't have the statistics
 AC> but ONCE UPON A TIME [pre 1912 I suppose], the World Speed Record was
 AC> held by battery electric auto.
 MR> Wow! You must be old to remember that! :-)
 AC> Nah. I read about that. I began to build my own EV in 1946. But I made
 AC> no progress beyond the controller. Those semi circular copper rods were
 AC> just too hard for me to file as I am basically clumsy.
You'll be happily surprised to learn modern motor designs have
progressed much beyond those primitive "semi circular copper rods".
Today's modern DC designs are brushless. Commutation is no longer
mechanical but electronic using Hall Effect switches to detect the
phase of the rotating magnetic field.
New more permeable metal alloys also make the motors much smaller for a
given power. So much so that instead of using 1 big motor you can
install an equivalent distributed motor drive for each wheel. What's
more these can also be used in regenerative braking which recuperates
the car's inertia, otherwise wasted as heat, back into electric power.
 MR> The subway system here in Montreal (somewhat similar to Paris) uses
 MR> motor control technology which accelerates the train so smoothly you
 MR> won't spill a drop of a rim filled coffee from 0 to 60mph. The stops are
 MR> just as amazing. It runs on inflated rubber wheels so it's very smooth.
 AC> On most rail systems, the lateral roll is too severe to risk rim
 AC> filled beverages.
The turns are banked. Taking a turn at 70 mph you feel like you're in a
race track oval. It's just next to a roller coaster thrill ride only
without the big G force loops. The route which goes under the
St.Lawrence River, crossing from Montreal to the South Shore, is the
best ride of them all! This subway was very innovative at the time
around 1965'ish and has constantly evolved development upgrades since.
 AC> Inflated rubber wheels incidentally are very wasteful of energy. A big
 AC> advance in battery EVs was the introduction of steel belted radial
 AC> tyres- pumped to considerably higher pressure than usual, these run
 AC> very cool and thus waste little energy.
 AC> ^^^^^
This subway uses slick radials and the wheels do get hot. There had been
the occasional tire fire in the early days though not any more. Better
rubber formulation I guess. Incidentally the brake shoes are made of
linseed oil impregnated wood because the alternative type would of
course fill the tunnels with asbestos fibers.
 Mike
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