Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1917-09-22
SPECIALISTS DESCRIBE CUNNEC BEL WEEN THE
ELECTRIC MOTOR AND THE ENGINE OF THE AUTOMOBILE
10y Special Permission from Motor
Aoel


The chief function OF tic starting
motor Is TO turn the gasoline engin"
over at such a speed that it may be
started readily, assuming the position
and intensity Of the spark, as we'll as
The gas mixture and all other COndi-
tons under which the starting motor
must be capable OF operating the en-
zine. in the majority of cases is be-
tween 100 and 200 revolutions min,
ute. II the starting motor Is connected
TO the engine in such a manner that It
must operate at the same speed as the
engine IL is evident that 1t must be
capable Of developing sufficient torque
50 that the torque available at the
gear or pulley on its shaft is just
equal to that required 10 drive the
engine at the desired speed.
ON the other hand, if the connection
between the motor and engine be
made in such a manner that the motor
may run much faster in revolutions
minute than the engine, the toruue
the motor must be capable OF produc-
ing at the gear or pulley on its shaft
relation TO the torque required to drive
the engine as the speed Of the engine
bears to the speed OF the motor
For example. II certain engine re
quires torque of 30 pound feet to
drive II at speed Of $50 revolutions a
minute and the starting motor Is
Eeared to the engine in such a manner
that 1t operates at 40 times the speed
OF the engine, then the torque the
motor must be capable of delivering
at its gear or pulley will be neglect.
ing losses, equal to one one-fortieth OF
20, or pound feet. The losses be-
tween the gear on the motor shaft
and the shaft Of the engine must be
taken care Of by the motor IN addition
to driving the engine< that IL, the
actual torque Of the motor always will
be greater than the theoretical torque
required, due TO these losses. The
losses In some gear types Of trans.
missions may amount to az much as
40 per cent, while the manufacturers
OF certain types Of chain transmissiors
assert the losses are as low as per
cent. .-'. .-.... .--.-s J..
The size Of an electric motor cap
able Of delivering a certain horse-pow.
er depends on the speed at which the
motor Is to be operated, there being an
increase in size with decrease in
speed and, conversely, decrease in
size with an increase in speed. On
account Of the limitations in size OF
the starting motor, due to space and
weight requirements, It is obvious that
lit would be better to have the speed
at which the motor operates greater
than the speed of the engine. There
are several exceptions to this last
statement, and the principal ones are
found in the U. S. L. outfit, the Woods 1
dual power car and the Owen mag
netic, all of which will be explained |
in detail later. .--.
Connection Between Motor and
Engine. ". sr9s
The main requirement OF the con-
nection between the electric motor |
and the engine is to provided positive |
mechanical connection so that the i
power developed by the motor may be |
transmitted to the crank shaft of the |
engine. The mechanical connection is |
required only when the motor is driv.
ing the engine, and the construction |
and operation Of the intermediate de- |
vice should be such that power may be |
transmitted in one direction only. This |
can be explained better by assuming a |
definite case.
Suppose the ratio between motor !
and engine speeds in a certain install |
lation Is 80 to / and that the motor |
will operate the engine at 125 revolu-
tions a minute. When the engine |
starts to fire IL is operating at APP |
proximately 125 revolutions minute |
and the motor is operating at $3.50 |
revolutions a minute. The speed of |
the engine viii increase, aud when it |
reaches speed Of 500 revolutions |
minute the speed Of the motor will be !
$4,000, which is considerably above |
the safety limit, and the motor should |
be disconnected from the engine long
before this speed has been reached.
Several different devices are EN-.
ployed to overcome the above diff. |
Guilty, such as the ordinary Jaw !
clutch similar to that employed on all /
hand cranks, friction clutch, roller /
oyerrunning clutch. ratchet-and.pawl
oyerrunning clutch, wJrm-and.worm |
Wheel Benedix drive, electromagnetic.
ataarafad Yiriors " MIR 4