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Challenges
to apply to ATV the high performance automatic transmission
that withstands sever working condition
The
ATV (all terrain vehicle) is used under vary adverse conditions
such as in extremely cold areas below -30?, extremely hot desert,
or even in swamps, and its transmission requires very high durability
and reliability. Furthermore, to allow operation by persons
of various skill levels, simplification of operation such as
use of an automatic system was called for. Honda challenged
development of a compact HMT reliable enough to withstand the
adverse environment while permitting use of engine brake for
operations on various types of a terrain. |
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ATV used in a wide variety of environment |
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The conditions under which the ATV is used are
harder than one can imagine. For example, the reliability of
ATV sometimes makes a live-or-die difference in the extreme
coldness of Alaska. Sometimes, the ATV has to be sturdy for
towing a heavy object. Operations in sizzling desert or in water
such as in a swamp have to be considered “normal”
for an ATV. Effective engine braking is essential when coasting
down a steep slope. Not only for utility purposes, Honda was
trying to develop an ATV suitable for recreational uses such
as hunting, touring, etc. Thus developed is the electronically
controlled HMT system that fills such requirements for a high
performance automatic transmission as the mount-ability in the
engine, in addition to durability and reliability.
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ATV (all terrain vehicle)
The ATV is a vehicle exclusively for off-road use, and standardized
by ANSI, which is a federal standard of USA. [Vehicle width:
1,270mm or less, one-person seating, handlebar-type steering,
4 low pressure tires, sit-astride type seat, off highway]
Honda Four Trax Foreman Rubicon
[Water-cooled, 4-stroke, displacement: 499cc, horsepower: 19.9KW/6500rmp,
torque: 37.8Nm/5000rmp, Hondamatic working pressure: 35.6MPa
(max 60MPa)] |
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The HMT (hydraulic mechanical transmission) that ATV requires |
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In the development of HMT for an ATV, Honda aimed
to attain a level of reliability and performance unattainable
from a belt-pulley-type automatic transmission. Firstly, the
transmission has to be as durable and reliable as the engine
unit. Secondly, the same level of engine brake as a gear transmission
has to be maintained. Additionally, the system has to allow
smooth running while providing the rider with a directly-linked
feeling, and the noises and vibrations that reduce comfort have
to be minimized. The noises and vibrations from the hydraulic
system and the transmission efficiency are the influential factors
of the aforementioned requirements. Lastly, the unit has to
be of a weight and size that permits mounting on an ATV. The
key to realization of such a system was how much higher the
working pressure could be increased. |
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