Figure 5-1.-Constant speed drive/starter.
The air turbine starter converts energy from
speed and high torque at the output shaft. When
compressed air to shaft power. This power goes
at the desired starter rotational speed, the
to a splined output shaft at speed and torque
flyweights in the governor assembly throw out and
values for starting aircraft engines.
open the limit switch. This section sends a signal
Initial control of the air shutoff valve (fig. 5-3)
that shuts off the supply air. At a higher,
is by a normally open, momentarily closed, start
predetermined rotational speed, the overrunning
clutch assembly releases the output shaft from the
switch and a relay box. After pressing the start
rotating assembly.
switch, the sequence of operation of the valve
A source of compressed air flows to the
and starter is automatic. A normally closed,
momentarily open, stop switch provides a means
shutoff valve inlet duct to drive the starter. The
starter is a turbine air motor equipped with a
of manually stopping the starter when motoring
radial inward-flow turbine wheel assembly,
an engine without fuel or in emergencies.
When the external start switch momentarily
reduction gearing, splined output shaft, and a
closes, a double-pole, single-throw, holding relay
quick-detaching coupling assembly. The complete
in the relay box actuates. This action completes
assembly mounts within one scroll assembly and
electrical circuits to the air shutoff valve and the
gear housing (fig. 5-2). As you read this section,
starter. When the external start switch opens, the
you should refer to figures 5-2 and 5-3.
5-2
