PART C - X1100-3B TRANSMISSION STEER SYSTEM AND FINAL DRIVES
The X1100-3B Transmission Steer System (fig. A-12).
The following paragraphs describe the steer
components, and operational characteristics.
a. Operating Characteristics.
The steer system consists of a
variable-volume hydrostatic pump, a fixed-volume hydrostatic motor,
and gearing by which the motor produces the steer action. While the
engine is running, the hydrostatic pump is driven continuously
through a gear train connecting the converter turbine to the
During straight travel, the hydrostatic pump
produces no flow or pressure; however, when steer is desired, the
pump does produce flow from either of two ports, depending whether
the steer desired is right or left.
The amount of flow produced
depends upon the degree of steer desired.
The flow of oil from either port of the hydrostatic pump goes to a
port in the hydrostatic motor.
This port then becomes the input of
the motor; the remaining port is the output and returns flow to the
pump inlet. Therefore, the inputs and outputs of the pump and motor
reverse when steering is changed from left to right, or right to
The direction of steer required determines the direction of
rotation for the hydrostatic motor.
The mechanical output of the hydrostatic motor connects, through
gears, to a differential arrangement which drives the sun gears of
two planetary gear sets in opposite directions.
arrangement remains stationary during straight travel, and the sun
gears act as reaction elements in the planetary sets, producing equal
rotation of the sun gears in the output planetaries.
steer, the differential sun gears are driven in opposite directions;
therefore, one of them adds speed to one output sun gear while the
other subtracts speed from the opposite output sun gear. This action
speeds up one power train output, while slowing down the opposite
output an equal amount.
Since the steer gear train has a fixed mechanical ratio (as do the
output planetary sun gears), the output planetary ring gear speed
ratio changes with each range shift and causes steering to be more
pronounced in the lower ranges. In neutral, pivot steer occurs.
b. The Oil Source (fig. A-13).
The hydrostatic steer system
receives oil at main pressure originating at the main pressure pump.
The oil passes through a 25 micron filter (main filter), main
control pumps and supercharge check valves.