Figure 5-3.-Air turbine starting system diagram.
control mechanism regulates the compressed air
through the nozzle vanes. The airflows against
to specified conditions. The mechanism senses
the blades of the turbine wheel to rotate
upstream and downstream conditions, and it
the turbine wheel. The reduction gear system
positions the valve butterfly to supply the desired
(fig. 5-2), which transmits power to the drive
flow.
shaft, converts the high-speed, low-torque output
The compressed air enters the inlet port of the
of the turbine wheel to low-speed, high-torque
starter and expands as it flows radially inward
output.
5-4