Richmond times-dispatch. [volume] (Richmond, Va.) 1914-current, 1917-07-22
p|MPL|F|ED' LESSONS FOR
| CARE OF AUTOMOBILES
,eN.uny Of Planetary Transmissions Is
Continued by Expert Engineer
OF Times-Dispatch.
RELATION OF DRIVING GEARS
Develops Explanation
Why Ford Cars Have Tendency to
Start Immediately the Engine Is
Started-Answers to- Questions.
LESSON NO. As.
The Ford Transm ission,

W
fcopyright. 1917. Fred. C. .Guerrlich.)
In studying the forward drive gears
IPf the Planetary transmission. VIC saw
hat ms the diameter and number OF
The teeth in tho gears approached one
another that the speed ratio would be
nhnity to ono, or. in other words
nc driven gear would not be moved at
pil. II the size OF the driven gear
pc now made smaller than it's driving
gear tyou will remember it was larger
Eor the forward drivc). then the driven
gear VIII be driven backward, or re-
verse. Like, for the forward drive,
me more nearly the gears are OF the
same diameter. the greater will be the
speed ratio and The greater the lev
S;:age.
Let us sec how the driven gear Is
harivcn backward. Figure / shows the
arrangement of the gears for reyers-
ing. Let us assume that the gear NJ
NAG seVcnty-five teeth. while the gear
mas but twenty-five teeth. then as
tthe hywheel and therefore. pin G re-
foiVes, In the direction Of the arrow
u. the gear o Will roll on the gear NJ
revolving on the pin c in The direc-
ZION Of the arrow 2. In doing 80. Now,
as . has but twenty-five teeth. II will
nave made ono revolution when it's
twenty-five teeth have rolled on TWEEN
ity-nve of the seventy-fve teeth OF ~,
iand SO when the hywheel and pin c.
have made a complete revolution, O,
IN orcer to have come In contact with
Ire scventy-fve teeth of 81. will have
had TO make one revolution. plus fifty
teeth. or three revolutions. a Will
again. therefore. be in the position
shown in figure /.
Now. as the gear F is attached to
the gear Q. when gear has made
three go revolutions. + will also have
mad TO make this number of rcvolu.
lions. Were the gear l. and the driven
gear T.; that is. the gear attached TO
tho propeller shaft. of the same d.
tameter and number OF teeth. then the
gear r VIII have had to move in the
direction OF the arrow 3. or backward
Tor two revolutions. tThc teeth o.
both gears will touch three times.
but because is rolling around +, f.
VIII make only two Revolutionary Thus.
for each revolution of the gear T, and.
therefore. propeller shaft, the hywheel
and, engine will have TO make two rev.
olutions. and the speed ration will be
2 to /.
Now tho driven gear e and Its driv.
Ing gear must be the same. for both
the slow speed forward and the re-
VnsFse drive. For forward drive we
assumed that the driven gear had sixty
teeth and it's driving gear forty. How
Will this AFFECT the speed ratio of the
reverse as above? It will Increase the
ratio.
AS the f0-toothed gear makes revo-
lutions. II will come in contact with
40 teeth OF the 60-toothed gear Z, or
II Will make 3 revolutions TO for T.
Thus the pin and engine will have to
make three divided by two times two
or revolutions for one OF the driven
gear, giving speed ratio of 70 /.
In practice the gear F. and the
s!ow-speed gear are built into one
piece. called triple gear For the
sake OF balance and to allow thinner
gears to be used. there are three of
these triple gears and three pins C on
the hywheel for them.
Having the three triple gears mesh
ing with single set Of center gears
makes 1t necessary that the gears he
'f'med. For this reason a prick punch
mark is made on them. and when as
sembling, these punch marks must be
SO placed that they come to the marks
on the center gears Unless this be
done, the gears will not go together
In some planetary transmits ions no
mark will be found on the center gears