Cub Cadet ISeries - Manual (Page 35)

DRIVE SYSTEM-IVT
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There are two drive systems available for the I-
series tractor. One system uses two HydroGear trans-
missions. The other system uses an Infinitrak full-toroi-
dal Infinitely Variable Transmission (IVT). This chapter
will cover the IVT version of the tractor.
The Infinitrak full-toroidal Infinitely Variable Trans-
mission (IVT) removes the constraints of conventional
stepped ratio transmissions. Instead of using a system
of gears to determine the ratio range, the IVT uses a
variator that is made of a set of discs and rollers called
a “full toroidal” variator. In the IVT, the torque is con-
trolled allowing optimization of the power train by allow-
ing the engine to run at its most efficient RPM range
and stay there.
The IVT used on the I-series is a twin variator ver-
sion. This means that there is one input and two out-
puts. See Figure 5B.1
Figure 5B.1
“T” box Input shaft
Variators
The power from the engine is transferred to the
transmission via a belt and pulleys. The power is
applied to a “T” box assembly. The “T” box output
drives the inner discs of the variator assemblies.
See Figure 5B.2
Each inner disc drives a pair of rollers that drive the
output discs. The angle of the rollers determines the
speed of the output discs. When the rollers rides near
the center of the input discs, they are pressing against
the outer edge of the output discs. In this position, the
output disc will be turning at a much slower rate than
the input discs. See Figure 5B.3
Figure 5B.2
“T” box assembly
Inner disks
Figure 5B.3
Input discs
Rollers
Output disc
500 rpm
50 rpm
CHAPTER 5B: DRIVE SYSTEM - IVT TRANSMISSION