by a hand lever, others by push
button; however, the resetting
procedure is always apparent on
sight. Since the engine overspeed
trip is a safety device preventing
the engine from excessive high
speed, it should always be
inspected before the locomotive is
operated. Figure 2.14 shows an
engine overspeed mechanism operated
by a lever.
Figure 2.13. Auxiliary Generator
With a Brush and
Brush
Holder
Visible.
2.16. GROUND RELAY
A ground relay is installed in the
main power circuit to warn the crew
if a ground develops in the
circuit. When one occurs, the
relay trips, causing an indicator
light to come on or an alarm bell
to sound, and on some locomotives,
reducing the engine speed to idle
and disconnecting the traction
motors. A red indicator, visible
through the trans parent cover on
the relay box, appears when the
relay has been tripped. When the
reset button, located on the ground
relay cover, is pressed, power can
Figure 2.14. LeverOperated Engine
once more be delivered. Because
Overspeed
Trip
the ground relay is a safety
Mechanism.
device, it should be checked before
the locomotive is operated. The typical ground relay illustrated in figure
2.15 shows it after it has been reset. Never use the ground relay cutout
switch (fig. 2.15) because a great deal of power circuit damage could
result.
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