The Oskaloosa herald., 1915-09-30


running on a wet pavement with the
brakes applied2
The differential action will allow one
wheel to revolve clockwise, while the
other turns antt-clockwise, but with
the brakes applied and holding well
neither wheel should turn. In the
case you mention the brakes evidently
were slipping and thus permitted the
wheels to turn.
In setting motor for high speed
work what changes should be made in
the ValYs. tirplnsa
The most, important and effective
change is to keep the intake valve
open for longer period.
Kindly explain just how baokfirs 10
caused. and why this should, happen
any more with a weak mixture than
when the mixture is rich. Also where
does the baekfire start?
A backf1re Is possible with either. a
weak or. rich mixture, although more
common with the former, because a
weak mixture burns more slowly. The
backtire starts In the cylinder and is
due to the. presence Of flame In the
combustion chamber when the intake
valve opens to take in q fresh charge,
If the combustion Of the charge is
very slow there will be fame In the
cylinder, not only all through the pow
er or expansion stroke, but also
through the succeeding exhaust stroke.
so that what gas remains in the, cylln'
der when the exhaust valve closes and
the intake valve opens Is still incan-
descent and sets the fresh charge on
fire the moment it comes In contact
with it, thus producing backtire.
Ordinarily a baekfire can only be pro-
duced by a weak mixture at high
speed, say 1000 revolutions per min
ute, although with very weak mix
ture or a very late spark backtire
may be produced at a much lower
speed, say 800. 1t is possible to make
the motor backfire by using too rich
mixture also, but the overrtch mixture
burns faster than the one that IS too
lean, and therefore the former Is gen
orally burned otit before the intake
valve opens.
Will, larger valves increase the power
and speed Of motor? ~. ..~'
Large valves are essential to power.
Large intake valves especially add
much to the power of an engine.
What do cylinders offset from the
crank shaft mean7
An offset cylinder is one whose axis
is offset from the vertical plane
through the crank SHIFT. That Is a
line drawn vertically through the
crank shaft center. In Offset cylinder
when the piston is on top
dead center the connecting rod Is not
directly In line with the crank shaft.
but, rather, makes an angle with 1t.
Cylinders are Offset so as to dimin-
ish the side pressure exerted between
the piston and cylinder when the PTS
ton is on the firing stroke, accomplish
ed here by reducing the angle of the
connecting rod when the pressure upon
the piston is great and increasing the
angularity when the pressure is low.
What is meant by easshardenins?
Casehardening refers to a process
of producing a hard coating of metal
over a piece of steel. The process con
sists in heating the. metal and then,
lightly sprinkling potassium cyanide
over it while. it is hot. This causes an
action between the metal and the cy-
anide, with the production of coating
which is very hard, This case or coat
Ing has good wearing qualities and
protects the inner metal, which is soft
er and acts as cushion for the case.
Aside from the cyanide mentioned
above, charcoal is used or charcoal
mixed with barium carbonate.
Can a high tension magnetic that runs
at crank shaft speed and rotates clock
Wise be timed or changed to rotate in
the opposite direction, or anti-eloek-
wise? <@
b The magnetic referred to can he
changed to run anti-clockwise by sim
ply removing the gears from the dis
trlbuter and resettfng them so as to
carry the current over the points OF
contact throughout the full range OF
spark advance at fullretard and at full
advance. Simply take the gears out
Of the distributor. revolving the arn1a-
ture by hand in an anti-clockwise d.
Fection, and when the position In which
the armature turns requires a good
deal OF force to continue the turning,
due to the pull OF the magnetic. insert
the gear In the distributor so that II
Is just coming into the metal contact
II the model magnetic referred to has
ia roller type distributor the same op-
Grafton holds good. except that the
roller with the internal gear should be
set so that the contacts are just meet
ing the small metal roller.
What advantages are gained by IT.
ting three piston rings 70 the groovs
instead Of ens7
The advantages claimed for special
piston rings are that they hold compress
sion better, prevent Oh from entering
the compression chamber more elfec-
Trials ana ~ 45tss4A aemaa Nn4rrn tina