tested also on country roads and muddy roads to see if the
machine could be used for agricultural purposes in addition to recreational riding . The tests were repeated again and again
to ensure themselves that the vehicle could run on such terrain
easily and safely . As the testing progressed , other specifica tions began to develop .
During Mr . Takeuchi ' s continual modification and
testing of the prototype , certain other aspects of the ATC
vehicle became clear .
The thumb - throttle , for instance , was
decided upon because it gave the rider the ability to hold firmly
onto the handlebars and make body movement inputs while applying
constant pressure to the throttle .
The differential , which had been considered for the
off - road vehicle as it is applied to on - road vehicles , met with
an obvious problem .
In driving any vehicle on an off - road
terrain , one wheel can inadvertently leave the ground
momentarily , because of the bumpiness and uneven character of the
If a differential is used , it can allow the wheel not
in contact with the ground to speed up . When it regains contact
with the ground this driving wheel will be moving at a different rate . This can cause a yawing torque , which may disturb the
rider and his control of the vehicle . Mr . Takeuchi discovered
that by shifting one ' s weight in a natural way during a turning
maneuver , a turn can be negotiated very easily . With a live rear
axle between the driving wheels , both wheels will be turning at
the same rate , whether or not they are in contact with the ground