1.3 Single rear wheel 3-Wheelers:
Third component layout: The 3-Wheelers with rear-engine and a single-rear driving wheel. Their rear engine and single rear wheel assembly usually comes from a regular 2-Wheel motorcycle.
The 1977 Phantom was among the first well made ones:
This group also includes the Doran and the Tri-Magnum:
It also includes the FireAero and even Bill Badsey's Fun Machine:
More recently, Grinnall's Scorpion appeared in England:
The same concept was used by Daniel Campagna to build his first 3-Wheeler:
The aesthetics were greatly improved by Designer Paul Deutschman, which gave the T-Rex:
This third component layout also includes the Cyclone at the right. It was developed by a team of engineering students in Sherbrooke and design students in Montreal. The Cyclone is equipped with a snowmobile engine that drives a belt and variable sheave transmission:
Other 3-Wheelers similar to the T-Rex have also been fabricated by enthusiasts, like the G-Max below:
Problems with this 3-Wheeler layout:
The Scorpion's esthetics are very good.
But despite the imagination, patience and hard work of these people and despite the capabilities of their 3-Wheelers, this 3-Wheeler group presents problems:
1) Mechanical design aspect:
2) Marketing aspect:
3) Stability in curves aspect:
the vehicle may have to
accelerate strongly and turn at the same time, for instance at a road crossing
like to the right.
A skilled driver may keep control and even have fun lifting off one of the front wheels of the Scorpion or the
T-Rex, as shown below.
But a beginner or even an average rider may be surprised and may be incapable of avoiding an accident.
4) Road holding aspect:
First, the two front wheels have to be moved farther apart to insert these passengers, so the vehicle has to be very wide. This explains why such 3-Wheelers are typically as wide as a Cadillac.
Second, if the passengers are moved forward, weight is removed from the rear wheel. So the powerful motorcycle engine can spin this rear wheel and cause the vehicle to spin around, even more so on wet pavement.
This can happen when accelerating in a highway entrance or exit. It can also happen when leaving a street intersection like at the right:
Someone reported to us that he was the passenger of such a 3-Wheeler that
spinned around when accelerating straight ahead:
The Morgan Trike of the 1930's also was a rear-drive. It was known to exhibit this problem on wet roads, with an engine less powerful then the ones of today's powerful motorcycles and 3-Wheelers.
A skilled driver may have fun turning fast enough to have his vehicle wheels skidding sideways. But one certainly has to be skilled to detect the moment when the rear end of such a 3-Wheeler will let go and start spinning the vehicle around. Here again, a beginner or even an average rider may be surprised and may be incapable of avoiding an accident.
In practice with this rear-engine and a single-rear driving wheel concept, designers have to accept
in-between compromise, both limiting ground traction when accelerating and limiting stability in curves.
But despite its performances in curves and accelerations, it also presents problems:
For safety's sake but also to avoid future litigation problems, a serious manufacturer of such a 3-Wheeler should make sure that his clients are aware of these problems before driving off in one.
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