Service Manual

Carefree Mower Service Manual 5 - 1
BLADE STOPPING SYSTEMS
Blade Stopping Systems
There are two blade stoppin
g
systems in use on the
various battery and electric powered mowers — one for
the 120 vac models and the other for the battery
powered models. Both systems are desi
g
ned to stop
the blade within three seconds of the operator
releasin
g
the bail on the handle.
120 Volt Blade Stopping System
The 120 vac mowers use a sprin
g
loaded brake
applied to a brake drum. When the control bail on the
handle is squeezed, this brake is retracted by a means
of a cable (Fi
g
ure 51).
Fi
g
ure 51
0663-014
Battery Mower Systems
The battery powered models use a permanent magnet
motor. If you turn the armature of a permanent magnet
motor by hand, the motor becomes a generator. We
use that electricity to stop the motor. With the motor
running normally, the operator releases the handle.
The switch disconnects the battery from the motor then
connects the two wires from the motor to
gether
(shorting them together). By doing this, the electricity
the motor then generates is directed back into the
motor in the opposite direction. This results in slowing
the motor. Also, as the motor slows down, it generates
less electricity. Soon the two forces balance each
other out and the motor stops. This system is very
effective and does not require brake parts to achieve
the required stopping time. See “Switch Testin
g
” on
page 4 - 8 for the internal workings of the switch.
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