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AUTOMOBILE TIPS 601
The Wheel Alignment Gage
either the front or rear wheels, and indicates
to a fraction of a degree the position
of the wheel. A spring arrangement
automatically holds the gage tight
against the felloe of each wheel.
NEW SELF-OPENING DOORS
""THERE is a very progressive garage
in one of the Chicago North Shore
suburbs. Its great double doors are
opened many times in every hour and
seemingly by ghost power, for the person
who enters does not see who or what
it is that controls them. He drives his
car up to the doors and expects to see
some man come to them and pull them
open for him. Instead of that the doors
suddenly begin to open of themselves,
with a slow majestic swing. He drives
in, looks to right and left and sees no
one near, but as soon as his tail lamp has
cleared the doorway the big doors close
themselves behind him. When he goes
out they open for him just as he is ready
to leave.
Located in a loft at about the same
level as the tops of the doors is an electric
motor of the reversible type. This
motor operates, through a belt, two large
spools or drums around which wind two
strong wire cables. The cables are wound
on the drums in opposite directions so
that while one of them is winding on the
other one is winding off. One of them
pulls the doors open as it winds on the
drum, and the other pulls them shut
again.
The motor is controlled by
double throw double pole knife
switches located all over the
garage in convenient places so
that when it is necessary to open
or close the doors it is done
from wherever the operator
chances to be at work. He
throws the switch into one position
to open the doors and leaves
it there until they have reached
the end of their swing. Then
he places it in the neutral position
and leaves it there until he
is ready to close them. He may then use
the same switch or any other one in the
house, simply throwing it into the opposite
position from the opening one.
The novelty of this arrangement is in
the fact that the system is made foolproof.
Without the fool-proof addition
anyone who might open the doors by
means of one of the switches and then
leave the switch on after they have
Z^SWITW
""SWITCH
Diagram of the Self-Opening Door Circuit