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“Hondamatic”
applied to the four-wheel ATV “Rubicon”
The
infinitely variable, hydraulic mechanical automatic transmission
features high durability and superb drivability. The HMT “Hondamatic”
employed in the Rubicon has an integrated cylinder. The piston-type
hydraulic motor and the hydraulic pump laid on a common axis
transmit power and allow changing of the reduction ratio. The
system allows selection of various types of modes such as the
automatic reduction ratio control with a focus on using high
power output, or on high torque, etc. Manual shifting mode can
also be selected. In any mode, the reduction ratio is changed
smoothly and steplessly without using a belt or gears. |
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Power transmission route of “Hondamatic” |
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To explain the power transmission route of “Hondamatic”
employed in the Rubicon, firstly, the power (torque and revolutions)
generated from the engine is transmitted via the clutch, etc.
to the HMT and drives the swash plate of the HMT pump. The revolutions
are reduced and the torque is increased by the hydraulic pump
and the hydraulic motor, and the power is further transmitted
from the output shaft to the sub transmission. From there on,
the power is transmitted to the front and rear wheels via the
sub transmission having 2 forward speeds (L, D), neutral and
reverse.
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Hondamatic cut model
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Engine cut model
Click the picture for enlarged view |
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Outlines on how Hondamatic functions |
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The Hondamatic is a system that provides an output
from the pump and motor cylinder integrated with the output
shaft by converting the input power into hydraulic pressure
and by the movements of the hydraulic piston pump and the hydraulic
piston motor. That means that the input power is split in the
hydraulic pump into the hydraulic component and the mechanical
component. That is, the “hydraulic power transmission”
in that the power is transformed into the hydraulic pressure,
amplified in the motor side, and becomes the torque by which
the motor pistons turn the motor-side cylinder, and the “mechanical
transmission” in that the power is transformed into the
torque by which the pump pistons directly turn the pump-side
cylinder by the hydraulic reaction force. As the pump cylinder
and the motor cylinder are connected, and further integrated
with the output shaft, the two transmission powers applied to
each cylinder are given out as a single output. Thus, by supplementing
the low efficiency part of the hydraulic trasmission with the
mechanical transmission, high efficiency is attained. Detailed
mechanism of Hondamatic |
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Working principles of hydraulic transmission and mechanical
transmission |
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| Input |
Engine power output (torque
and revolutions)
Input gear
Pump-side swash plate is driven |
| Hydraulic |
(1)The seven pump pistons laid
on an identical radius are pressed one after transmission
another, by the angled swash plate, causing a hydraulic
pressure to occur in the cylinder
(2)The high fluid pressure acts on the opposing motor
pistons, and acts like pressing out the piston up to the
corresponding displacement of each cylinder
(3)By the reaction force from the swash plate, the motor
pistons provides the motor- side cylinder with the revolutions
and the torque Tm |
| Mechanical |
(1)The reaction torque from the fluid acts on the pistons
in the hydraulic pump
Transmission(2)The pump pistons press the pump cylinder
and provide revolutions and torque Tin |
| Output |
The output shaft integrated with the cylinder is driven
to the sub transmission |
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The rotation force F coming in the pump swash plate produces
hydraulic pressure
When producing the hydraulic pressure, the piston presses the
cylinder wall by F’ |
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