CHEVROLET ENGINEERING 🏁 Transmissions & Synchromesh (1936 Original Company Documentary)


HOT ROD 100 Presents…
Chevrolet Synchromesh
(Company Archive Footage) meet mr. Archimedes of ancient Greece
long ago our key said give me a lever long enough and I can move the world
what Archimedes meant was that the power of a lever is practically unlimited
today almost everyone uses some form of lever in his daily work the familiar can
opener is a lever with a sharp cutting edge the playground seesaw is just a
simple lever – it takes a lot of force to start a freight car moving yet the
railroad man can start the heaviest freight cars easily with a pinch bar a
powerful lever which turns the wheel tough luck old boy here’s a place where
a lever comes in mighty handy let’s take the simplest kind of lever a rigid bar
working on a fixed support called a fulcrum one end of this lever is twice
as long as the other let’s put a 10-pound weight on this end and now
we’ll put half as much weight on this end five pounds balanced ten if we have
25 pounds to lift we just use a longer lever the five pounds will now balance
five times as much let’s raise the lever in the air change its shape a little and
we have a crank or we can add a second lever and have a double crank now the
short arm moves 1/4 the distance but we get four times the force if we want
continuous motion we need more arms now we have levers
that turn the larger paddle wheel makes fewer turns but it delivers more force a
paddle wheel is nothing but a never-ending series of levers we can
make the wheel stronger and lessen friction where the wheels touch each
other by rounding off the edges and shaping them into teeth that will slide
in and out smoothly now the power flows smoothly and continuously
through spinning leverage of gear wheels gears are made in many kinds and many
sizes little gears big gears worm gears bevel gears and even lopsided gears over
a hundred million gears are spinning over the roads and the transmissions of
our automobiles the transmission is located right at the bottom of the gear
shift lever let’s start from scratch and put together a model of the gears that
we shift in our motor car the shaft on the Left comes from the engine the shaft
on the right carries the power back to the rear wheels to connect these two
with gears we’ll need another shaft known as a counter shaft these two gears
carry the power from the engine shaft to the counter shaft and are always
connected or in mesh this gear on the drive shaft going to the wheels is free
to turn around the shaft we’ll put it in mesh with another gear on the counter
shaft these gears are always in May and keep turning while the engine is running to switch from one set of gears to
another our transmission needs a short shaft like this known as a clutch sleeve
it cannot turn on the drive shaft but it is free to slide back and forth on the
sleeve will not a large gear which we can shift back and forth to mesh with
the small gear in the middle of the counter shaft we are now in neutral the gears that are
always in mesh are turning over with the engine but the shaft to the rear wheels
is standing still a three thousand pound automobile takes a lot of force to start so in low speed we get the greatest
leverage by letting the smallest gear on the counter shaft turn the largest gear
on the drive shaft the engine on this model is running at a constant speed of
90 revolutions a minute with low gears in mesh the rear wheel is turning at 30
revolutions a minute about a third the speed of the engine but with three times
the force the power is going through these gears in the transmission after we’ve started the car rolling we
want fast pickup so we shift into second by sliding the sleeve backward to mesh
with this gear on the shaft to the rear wheels the wheel is now turning at 60
revolutions a minute and the power flows through these gears for higher speeds we
let the power go directly to the rear wheels we shift the sleeve forward so
that it meshes with the shaft from the engine the power travels straight from
the engine to the drive shaft now the shaft to the wheels is turning at 90
revolutions a minute the same speed as the engine but here’s a problem an
automobile must be able to go backward as well as forward so we add one more
set of gears to reverse the shaft to the rear wheels with the gears shifted into
reverse the power travels through the transmission in a path like this we now
have three sets of spinning levers for going forward at one for Reverse with a
gear shift lever we can shift to any set of gears we wish but with all these
spinning levers in the transmission came noise and where experts could shift
gears quietly by careful timing of the gear shift and the engine speeds but
most of us made plenty of noise until new engineering developments made
possible a long series of improvements that followed when we shifted gears we
got a clash because the gears were not running at the same speed in other words
not synchronized so engineers set to work to develop a synchronizer the
synchronizer works like a cork twisted into the top of a bottle the cork will
turn until it is so tight that the bottle turns with it synchro mesh
works the same way when we shift into second or hi the synchronizer brings the
gears to the same speed before they come together the drums won’t let the gear
shift unless they are turning at the same speed when the gears come together
there is no clash and the shift is made quietly and easily in the transmission
of the up-to-date automobile we have a powerful low gear to give us a strong
spinning leverage in starting a fast turning motor must set the weight of the
car in motion in second speed we can change leverage to get going fast at the
same engine speed with the leverage of third gear power goes directly to the
rear wheels and we can go as fast as we want now every driver can shift gears at
any time regardless of speed here is a hill that will give us a real chance to
see how smoothly and reliably our spinning levers work in our automobile
transmission this driver is going to let her car gain a speed of 60 miles an hour
down the hill then she will shift into second speed
and bring her card easily and safely under control before it reaches the
bottom of the hill