Typical Cycle of Piston in One Cylinder of Ford Engine
Piston moves from top center down on its intake stroke. The intake valve opens 1/16"
past top center thus allowing the piston opportunity to reduce the pressure in the combustion
chamber caused by the previous exhaust stroke before opening the passage to the intake manifold.
The piston travels downward drawing the gas mixture from the carburetor into the cylinder. The
intake valve is held open until the piston is 9/16" travel past bottom center on the next up
stroke. This lag of intake closure allows a greater volume of gas to force its way into the
cylinder than if the valve were closed at bottom center, due to the great inertia of the gas
which travels through the opening at 4000 to 5000 feet per minute. On the succeeding up stroke
of the piston the gas is compressed to 40 to 60 lbs. pressure, both valves of course being
closed and the cylinder head gas tight. At, or slightly before, the top center of this stroke
the charge is fired and the piston is forced downward by the expansion of the gas on its power
stroke, 5/16" before the bottom center of this downward stroke the gases have practically
exhausted their useful energy and the exhaust valve is opened at that point On the succeeding
upward stroke the exhaust valve is fully opened and the burnt charge is forced out through the
exhaust manifold. At the top center of this stroke the exhaust valve is closed and the piston
repeats its cycle.
The head is bolted to the case with 7/16" No. 14 U.S.S. thread bolts, 15 in all. The
magneto coil is now bolted to the radius at the rear end of the case. It is shimmed so that the
distance from the crankshaft flange to a plane passing through the face of the coil is 27/32".
The Ford transmission is built with the flywheel as a unit. This weight added to that
of the magnets carried on the flywheel makes possible the use of an unusually tight flywheel
casting. The distance from the magnet clamp faces to the depression in the center to which the
crankshaft flange is bolted should be 13/16"-53/64". The flywheel and transmission assembly is
bolted to the crankshaft flange with four l-3/16" x 7/16" x 20 thread Cap Screws and is located
by two pins .468" in diameter. The clearance between the faces of magnet clamps and coil core
faces should be not less than .025" or more than .040".
The Manifolds, intake and exhaust, are bolted in position connecting to their proper
ports with copper and asbestos gaskets interposed. Studs 3/8" x 24 thread, clamp and nuts are
used for this purpose. The magneto contact point is fastened to the transmission cover by
three screws and the engine assembly is completed.
The block consists of a support for the assembled power plant, and a 20 H.P. motor
with suitable universal joint linkage to connect to the engine to be tested.
The engines are run on the block for a period of eleven minutes at a speed of 700
to 1000 R.P.M. The voltage of the magneto is tested by connecting the coil terminals to an
alternating current volt meter which should indicate 14 volts or more.
There are four important points to keep in mind at all times:
1. That there are three gears forming the triple gear assembly which are riveted
together (at the present time all are cut out of the one piece of steel), and whatever one gear
does the other two must do also.
2. That whatever the action of the 27-tooth central or driven gear is the action of t
he car; that is, when the car is standing still the driven gear is stationary, when the car is
going forward in low the driven gear is revolving in the same direction as the flywheel, but
at a lower speed, in high the driven gear turns in the same direction as the flywheel and at
the same speed; in reverse the driven gear turns in the opposite direction to the flywheel.
3. That the clutch is used only in direct drive or high speed.
4. That the triple gears are only used to get low and reverse.
When the car is standing still and the engine running, the neutral position is
obtained in two ways, either:
(a) by putting the control lever in the vertical position which causes the quadrant on the
control lever shaft to press the set screw upward in the end of the cross shaft of the "T" shaped
clutch shift shaft. This in turn presses the clutch shift backwards, compressing the clutch
spring. Pressure is thus taken off the clutch discs and the small discs permitted to turn with
the engine but not transmitting power to the large discs which are fastened to the brake drum,
drive plate, drive plate sleeve, universal joint, drive shaft, and rear axle.
(b) By pressing the clutch pedal half way forward, and by so doing the extension on the lower end
of the pedal presses the clevis which connects the pedal and clutch shift shaft downward; this
turns the clutch shift shaft and depresses the clutch spring the same as when the control lever
is pulled back.
When the car is driven in high or direct, the control lever is pushed forward so the
quadrant does not come in contact with the clutch shift set screw, and the clutch pedal is allowed
to come all the way back; this permits the clutch spring to press against the clutch fingers with
a pressure of ninety pounds, which in turn presses the clutch push ring dowel pins, and by the
leverage of the fingers increases the pressure from ninety to three hundred and twenty-four pounds.
Therefore, the small and large discs are clamped together with a pressure of 324
pounds making a direct connection with the crankshaft, transmission shaft, disc drum, small disc,
large disc, brake drum, drive plate, drive plate sleeve, universal joint, drive shaft, and rear
Action in Neutral
When the operator wishes to stop the car but not the engine, he presses the clutch
pedal half way down which permits the small discs to run independently of the large ones. Now
recalling Rule 2, that whatever the car is doing, the twenty-seven tooth driven gear is also doing;
if the car is standing still the stationary parts are the wheels, rear axle, drive shaft, drive
plate, universal joint, brake drum, brake drum sleeve, and driven gear.
In mesh with the driven gear are the three triple drive gears which also have 27 teeth.
The dowel pins, which are pressed into the flywheel, form the axes of the triple gears, so as the
flywheel revolves, it carries the triple gears around with it, and as the drums are free to revolve,
the 27 teeth of the drive gear just mesh with the 21 teeth of the driven gear in one revolution
of the flywheel; therefore, while the flywheel is making one revolution, the triple gears make
one revolution on their own axis, no more and no less. So you may see in order to have the car s
tand still while the engine is running, it is necessary that the triple gears make just one
revolution while the flywheel makes one revolution. If the triple gear makes more than one
revolution, power will be transmitted to the driven gear; if it makes less than a revolution while
the flywheel makes one revolution it will transmit power to the driven gear, but in the opposite
Driving the car in reverse is done by pressing the reverse, or central pedal, forward.
In doing so the band is tightened around the reverse drum which is the drum nearest the flywheel:
fastened to this drum is a 30-tooth reverse drum gear, which is also held stationary. In mesh with
the 30-tooth reverse drum gear is the 24-tooth reverse triple gear. The triple gears are all
fastened together and what the triple gear does the other two triple gears must do. When the
30-tooth drum gear is held stationary, the 24-tooth triple gear, which is in mesh with it, the
axis of which is fastened to the flywheel, revolves around the 30-tooth gear. But it is plain to
see that while a 24-tooth gear is revolving around a 30-tooth gear, it will turn six teeth, or
1/4 of a revolution more than a revolution, but in order that the car stand still, the triple gear
must make just one revolution on its own axis while the flywheel is making one revolution; so, if
the 24-tooth triple gear makes one-quarter more than a revolution while the flywheel is making
a revolution, the 27-tooth drive gear will also make 1-1/4 revolutions, and in doing so will
force the 27-tooth driven or central gear 1/4 revolution in the opposite direction, or the
difference between the one revolution that the drive gear must make and the 1-1/4 that it does
really make. Therefore, if the 27-tooth driven gear makes 1/4 of a revolution in reverse for
one revolution of the flywheel, it will make one complete revolution in reverse in four
revolutions of the flywheel. If the drive gear makes a revolution, the drive shaft will also. But
in order to get the ratio of the engine to the rear wheels there is another ratio in the axle to
The drive shaft pinion having 11 teeth and the ring gear 40 teeth, makes a ratio
of 40 divided by 11 = 3-7/11. Now in order to get the total ratio of the engine to rear wheels
in reverse the two ratios must be multiplied. 3-7/11 x 4 = 40/11 x 4 = 160/11 or 14-6/11.
If low speed is desired the clutch pedal or the one to the left is pressed all the way
forward. In doing so a band is tightened around the center or low speed drum which is held
stationary. The gear attached to this drum has 21 teeth. The triple gear that meshes with this
21-tooth drum gear has 33 teeth. Now remembering the action in neutral, the triple gear makes
just one revolution, while the flywheel is making one revolution. In reverse there was action
transmitted to the driven gear because the triple gear made more than a revolution while the
flywheel was making a revolution, but in the case of low the triple gear makes less than a
revolution while the flywheel makes a revolution.
The 21-tooth gear being stationary the 33-tooth gear revolving around it only permits
21 of the 33 teeth to be used. In high or direct drive the triple gears are not in action at all,
the gears are all meshed together and act as a lock and carry the transmission assembly around as
a unit at the same speed as the flywheel. In neutral the 27-tooth drive gear simply idles around
the 27-tooth driven gear and there is no action transmitted to the driven gear. These are the two
If the 21-tooth drum gear is held stationary, the 33-tooth triple gear revolves around
it, and instead of the triple gear making 1/2 revolution while the flywheel is making a revolution,
it makes 21/33 of a revolution, because while it is traveling around the drum gear only 21 teeth
of the 33-tooth triple gear are used. If the 33-tooth triple gear makes only 21/33 of a revolution
the 27-tooth drive gear makes only 21/33 of a revolution; therefore, the triple gears lack 12/33
or the difference between 21/33 and 33/33 of making a revolution on their own axis while the
flywheel is making a revolution.
The right hand pedal is the brake pedal, and when this pedal is pressed the band
is tightened around the brake drum, and being connected directly to the rear axle, stops the
car whenever the drum is stopped.
Parts of the High Tension Jump Spark System
The Ford ignition system is known as the High Tension Jump Spark System. It includes
the following parts:
Magneto---to provide current (alternating)
Induction Coil or Coil Units---to transform the primary (magneto) current of 8 to 30
volts into a secondary current of 8000 to 20,000 volts. This is necessary, as a current must be
provided which can jump an air gap of at least 1/4 inch.
Commutator or Timer---(a) to close primary circuit and produce a spark in the
cylinder at the proper time to fire the charge and start the power stroke; (b) to control passage
of current through different coils according to the firing order; (c) to advance and retard
Switch---to start or stop current.
Spark Plug---to conduct high tension current into combustion chamber and
provide a gap across which it can jump so as to ignite the explosive mixture.
Wiring---to conduct current from one part to another.
Type-Flywheel type, rotating magnets, stationary field, alternating low tension
current. This magneto is of the inductor type, but unlike the other inductor type magnetos,
the magnets themselves serve as inductors. It is designed to be mounted on the flywheel, thereby
becoming a part of the power plant. It is protected from mechanical injury and moisture which
tends to short circuit and damage it, by the same case that houses the transmission. The coils
are stationary to avoid trouble from commutation or moving contacts.
Magneto---is composed of 16 "V" shaped permanent magnets, mounted on, but
magnetically insulated from the flywheel, and sixteen coils wound of insulated copper tape, one
quarter of an inch wide and .015" thick, 25 turns to a coil, mounted on bosses on the magneto
frame. The coils are wrapped with cambric, with fiber inserts in the center, and bristol board
insulating washers beneath when mounted on the bosses. The coils are connected with the winding
of consecutive coils in opposite directions.
Magnets---are mounted with similar poles of adjacent magnets together making
16 magnetic poles each, having twice the strength of a single magnet pole, so in each revolution
of the flywheel the magnetism in the boss of each coil reverses sixteen times, producing sixteen
electrical impulses, which at ordinary engine speed produces a continuous alternating current of
a much higher frequency than is used for house lighting. Because of this fact it is possible
to operate lights from the magneto.
The Coil Unit
The coil unit consists of a soft iron core, primary coil, secondary coil, condenser,
and the upper and lower bridge. The coil unit is also called an induction coil. Induction is the
process by which a current is produced in one wire by another current running in another wire,
near the first but not touching it.
Construction---The soft iron core is made up of 160 to 170 pieces of No. 20
Swedish soft iron wire and well insulated from the primary coil, which is wound around it, by a
heavy paper tube in which the core is packed.
Primary Coil---is made up of two layers of No. 19 insulated copper wire, the
first layer having 112 turns and the second 110 turns. The primary coil is then impregnated in
hot paraffin and rosin for 20 minutes. This cements the pieces of wire in the core together,
insulates and holds the windings of the primary in place.
Secondary Coil---is composed of 16,400 turns of No. 38 enameled copper wire,
and between each two layers are three layers of paper insulation. The coil is wrapped in two
spools with forty-one layers on each spool. The reason for building the coil in two spools is
because there will not be as many volts difference between the consecutive layers at the same
end of the coil as if it was wound in one spool. By wrapping in two spools the difference in
voltage between the consecutive layers at the same end is just half as much as if it was wound
in one spool, and consequently, the thickness of the insulation between the layers is reduced
one-half and the diameter of the coil is reduced proportionately. The secondary coil is then
placed in a vacuum tank for twenty minutes at 220 degrees F. to make sure all moisture is drawn
out; then it is submerged in hot wax. A heavy piece of wax paper is wrapped around the primary
coil and it is placed within the secondary coil, making the induction coil complete.
The Condenser---is composed of two pieces of tin-foil 7 ft. long and 3-1/2" wide.
One piece of this tin-foil is placed on the other one but 1/8" to one side, with two layers of
glassine paper insulation between and one layer on top and one layer on the bottom. It is then
rolled up into a roll and placed in a vacuum tank for twenty minutes at 220°F. and then boiled
in paraffin for twenty minutes, after which it is taken out and pressed, and to each end
terminals are attached. The condenser must test from three to four microfarads. The condenser
terminals have no electrical connection within the condenser. These terminals are connected in
the primary circuit with one terminal on each side of the contact points. The condenser is used
to absorb the current of primary windings at the breaking of the contact points and thus prevent
it from arcing across the points, which would soon burn them. As soon as the condenser is
charged it seeks the path of least resistance to discharge or neutralize itself, which is through
the coil in the opposite direction. This causes the magnetic field about the coil to collapse
very quickly. The more rapid the fall of the primary current the greater the force of the induced
current in the secondary winding.
The Upper Bridge---is stamped out of brass and to this at the terminal post end is
riveted a cushion spring which is stamped from bronze. The other end of the cushion spring
contains a tungsten steel point and this end is held from .003 to .005" from the upper bridge by
a spacer rivet.
The Lower Bridge---is a copper spring by means of which the amperage can be
adjusted by increasing or decreasing the tension on the armature which is attached to the lower
bridge by means of two screws. The armature is stamped out of Swedish steel and has a tungsten
steel point on the free end, directly under and in line with the tungsten steel point on the
The parts are placed in coil box, with the exception of the upper and lower bridge,
which are placed on top, in their relative positions and tar from 300 to 350°F. is poured around
them, holding them in place, insulating them from each other, and protecting from dampness.
The space between points is adjusted from .029 to .031". Coils are adjusted from 1.2 to 1.4
The commutator effects the make and break in the primary circuit. On it depends
the point at which the spark plug will fire.
Parts of Commutator or Timer: roller brush or center, segments, shaft, terminals,
cover. The roller is attached to the end of the camshaft and revolved with it at half the speed
of the crankshaft. The brush or roller makes contact with the insulated contact points, of
which there are four in the commutator cover. When roller comes in contact with one of the
insulated points, the coil unit connected with it becomes operative. After the roller passes
over the point, the coil unit is inoperative. The commutator cover is connected with the
spark lever on steering column by a pull rod connection. By this lever the spark is advanced
The oiling system employed on the Ford Model T car is known as the "constant level
circulating splash system." The oil is poured into the breather pipe at the right side of the
front of the motor, from which it flows over the connecting rod troughs of the crank case lower
cover (leaving them full), and into the lowest part of the crank-ease under the flywheel. When
the motor is running the oil in the bottom of the crankcase is carried by the flywheel and
magnets near the top of the transmission cover. Here a portion of it drips into the
funnel-shaped upper end of the oil pipe where it flows by gravity down to the timing gears,
returning once more to its original position under the flywheel. The oil pipe mentioned is
the only one used.
No pump is required in the Ford system. All moving parts of the motor are kept well
oiled by this system. The only opening into the crankcase is the breather pipe. Any oil which
may be "pumped" to the top of the pushrods is automatically drained back Into the crankcase
by two small holes, just inside the valve door. The Ford oiling system is highly efficient,
has proved satisfactory over a long period of years, and is more fool-proof than any other in
use today. The only attention required, other than replenishing the oil supply from time to
time, is to wash out the crankcase every 750 to 1,000 miles.
It is light in weight, strongly built, an efficient cooler, and is easily repaired.
It permits an easy circulation of both air and water. Such is the radiator on the Ford Model "T."
The use of a large number of small tubes fitted into a series of flat strips of sheet metal
(or fins) makes a core which is more substantial and more efficient than the almost obsolete
type of large tubes surrounded by helical fins. The top tank and sides of the Ford radiator
are covered by a shell of black enameled sheet steel which enhances the appearance of the car,
and has a more durable finish than would be possible were the enamel applied directly to the
radiator proper. This is simply slipped on, and held in place by the two bolts which hold the
radiator to the car frame's side members.
The parts of the Ford radiator are: filler cap, filler cap gasket, filler flange,
top tank top, top tank front, top tank back, upper header top tank top reinforcement angles,
splash plate upper water connection, overflow pipe, overflow pipe straps, hood rod socket; hood
rod socket washer, side walls, fins, tubes, support, lower header, bottom tank, bottom tank
brackets, lower water connection.
The radiator core or body conists of 95 tubes 1/4" in dia., 17-3/8" long, and 0.005"
in thickness), 87 fins, radiator support, and the lower header. When the core has been assembled
it is placed on a conveyor which carries it through an oven at 425°-450° F. This temperature
is sufficient to melt the solder on the various parts bf the core, thus automatically soldering
them rigidly in place; Both water connection, hood rod socket, and radiator support are tinned
to prevent their rusting when in contact with the water.
The fins of the latest Model "T" radiator present a combined radiating surface of
54.63 sq. ft. The 95 tubes expose to the air an additional area of 8.94 sq. ft. Thus we find
that we have a total radiating surface of 63.57 sq. ft. A better comprehension of this area can
be had if we consider it as the area of a plate 8 ft. wide and 8 ft. high. All this is
accomplished in a radiator core 19" long, 2-5/8" in breadth, and 17-3/8" high.
The 95 tubes of the Ford radiator hold 70.58 cu. in. of water or 17% of the water in
the entire radiator. Each cu. in. of water in the tubes has a radiating area of 113.6 sq. in.
Of the 3 gallons of water in the Ford cooling system 2 gallons is in the radiator; the remainder
is in the water jackets of the motor and the two pipes leading to them.
Construction and Material Used---the frame is made up of two long straight
side members, and front and rear cross members. Side members are made of channel section
pressed steel. Front cross member is bent down to form a support for the semi-elliptic
transverse spring. Rear cross member is bent upward to fit the arch of the rear cross spring
and to add more strength.
Dimensions---Length of side members of the Model "T" 100 inches.
Length of side members of the Model "TT"--- 123-25/32inches.
Width of front cross member of Model "T"--- 23 inches.
Width of front cross member of Model "TT"--- 23 inches.
Width of rear cross member of Model "T"--- 25-1/8" to center line of bracket holes.
Width of rear cross member of Model "TT"--- 32-5/8" to center line of body bracket holes.
Method of joining parts---Hot riveting.
By this method the rivet contracts as it cools, thus filling the hole in frame.
Brackets---These are used to support the body, running boards, truss rods, fenders,
lamps, control rod quadrant. They are fastened to the frame by rivets, excepting the fender and
lamp brackets, which are bolted.
Truss Rods---Purpose---To give added support to the frame. Are used on running board
The Rear Axle
The most Important parts of the rear axle are:
The universal joint.
The drive shaft
The drive shaft housing.
The drive shaft roller bearing housing.
The drive shaft pinion.
The differential drive gear.
The differential assembly.
The two axle shafts.
The two hub brake camshafts.
The two-hub brake pull rods.
The two hub brake shoes.
Right half rear axle housing.
Left half rear axle housing.
The universal joint consists of a male and female knuckle joint which are assembled
in two rings---riveted together; when assembled this forms a link in the train of power
transmission through which power can be sent at any angle not exceeding 45 degrees. The male
knuckle has a square end which slips into a square hole in the transmission drive plate assembly.
The ball joint acts as a housing for the universal joint and holds it rigid and, at the proper
distance from the transmission. The female knuckle of the transmission fits over and Is pinned to
the square end of the drive shaft.
The drive shaft is 1.062 to 1.063 inch in diameter x 53-5/8 to 53-3/4" long. On the
upper end it is square and tapers at the other end about 1". It runs through the drive shaft
housing or torque tube to the differential assembly in the rear axle housing. The drive shaft
pinion gear is keyed to the tapered end and drawn up by a 5/8" x 18 thread castellated nut and
There are three bearings on this drive shaft. First, the babbitt bearing at the
forward end of the drive shaft, just back of the universal joint. This babbitt bearing is placed
there because there is very little wear or bearing strain at this joint. In reality this bearing
is simply a guide bearing. Next there is a Hyatt roller bearing at the rear end of the drive
shaft just in front of the drive shaft pinion.
When the car is in motion there is a tendency for the drive shaft to thrust up
toward the front This is due to the fact that the drive shaft pinion is a bevel pinion and meshes
with the differential drive gear, which is also bevel. This end thrust pushes the bevel drive
shaft pinion forward. Directly in front of this pinion is the drive shaft roller bearing and
in front of this the ball bearing which butts against the flange of the drive shaft tubing.
The Assembly of the Drive Shaft
In assembling these parts on the drive shaft the ball bearing is placed on first;
it is prevented from going beyond its proper position by the shoulder which is formed when the
end of the drive shaft is finished. A thick washer is next put on the shaft so that the end motion
of the roller bearing will not wear into the ball bearings. A hardened sleeve is pressed on to
the drive shaft, which is the bearing surface within the roller bearing. The drive shaft roller
bearing runs within a hardened sleeve, called the drive shaft roller bearing sleeve. This sleeve
is pressed into the drive shaft roller bearing housing, so this roller bearing runs between two
hardened surfaces. The new style roller bearing eliminates the outer sleeve.
The axle shaft is in two halves. On the inside end of each of these is keyed a bevel
gear placed far enough to allow a short end for a bearing. A short distance from this end a
groove is cut around the shaft. After being keyed onto the shaft, the differential gear is
pressed far enough back to allow two half rings, or circle keys, called differential lock rings,
to be placed in the aforementioned groove around the axle shaft. Then the gear is forced forward
and over the lock rings, holding them in place. This keeps the gear from coming off the axle
shaft when the wheel is tightened on the other end of the shaft.
On the back of the differential gears is left a hub which is ground to a bearing
finish for wear on the differential case. After placing the axles with the bevel gears keyed
thereto in the proper place in the differential case, the three differential pinions are placed
on the arms of the spider, and the spider is placed over the end of one shaft, which fills one-half
of the hole in the center of the spider and leaves the other half for the end of the other axle
A fiber washer 1" x 1/32" is placed between the two axle shafts to prevent noise by
not allowing the two shafts to butt together. The other half of the differential case is next
placed over the gear on the end of the other shaft. The two differential gears are then placed
in mesh with the pinions on the spider, and the two halves of the case are then drawn together
by three studs 3/8" x 24 threads and 2-1/4" long. Thus the differential proper is assembled
with the two axle shafts keyed thereon. The large ring gear or drive gear is bolted to the left
half of the differential case.
All roller bearings used in the Ford car are made of a high grade alloy steel of
rectangular cross section and wound in spiral form. The rollers are held in place in the races
by the "cage," which is composed of a flat ring at each end of the bearing; these rings are held
together by bars. In the case of the drive shaft bearing, there is a bar between every two
rollers, known as the high duty type. The races are made of a high carbon steel on account of
the high rate of speed as compared with the races on the axle shaft bearings, which are made of
low carbon steel, carbonized and case hardened.
The rollers are assembled in the "cage" so that the spiral runs in the opposite
direction on every other one. This condition assists greatly in the lubrication, as the oil
will run to the left on one roller and to the right on the next one, keeping the rollers and
races perfectly lubricated.
The bearings used on the rear axle run inside of a split race or lining; the slot
is "V" shape to cause a continuous contact when in operation; there are projections on the
lining used to locate it in the housing and the hole in the one on the outer end of the axle is
used for lubricating purposes. When the cages are assembled the bars are welded in place.
Dimensions "T" Rear Axle
Drive Shaft Assembly
Length and diameter of drive shaft--- 53-5/8 to 53-3/4 x 1"
Drive shaft sleeve---inside diameter 1" x 3-1/16" long
Drive shaft roller bearing---length---2-5/8"
Thread on end of drive shaft--- 5/8" x 18
Drive shaft tubing---50-1/2" long
Drive shaft tube is 49-5/16" from face to center of universal joint ball.
Drive shaft bushing---1" bore x 1-3/4"long
Hub diameter of differential gear---1.808"-1.809"
Gear case diameter---5.248"-5.249"
Diameter of gear end of axle shaft---1.062" to 1.063"
Bearing end of axle shaft--- 1.062" to 1.063"
Length of axle shaft--- 31-1/32"-31-3/32"
Babbitt thrust plates and steel thrust plates are all 3-3/4" outside diameter. Babbitt
Steel thickness--- .0875'-.0883" New .085"-.087"
Diameter of center hole in thrust plates 2.250"
Fiber washer--- 1 x 1/32"
Height of assembled differential case--- 3.623"-3.625"
Axle housings--- 26-3/4"
Housing diameter for roller bearing sleeves--- 2.208 to 2.211"
Diameter of bell 8.752"-8.754" inside of 9-1/4"outside.
From center of ring gear in housing to the face of housing for drive shaft tubing is
Brake pull rod clips are 18" from center of clips to center of radius rod bolt holes.
There is three inches difference in the top and bottom measurements between the
front wheels of the Ford. Because of the inclination of the wheels they have a tendency to
roll outwardly and pull away from each other. To counteract this tendency the wheels are
"toed" in slightly from the true parallel position; about 1/8" to 1/4" is the Ford setting.
Since the wheels, therefore, flare outward at the top their ability to withstand
a side blow which is nearly always applied at the lower part as in resisting a turn, is reduced.
However, this is circumvented by dishing the wheel; that is, by slanting the spokes outward at
the rim. Thus the declination of the wheel is offset by the inclination of the spokes, and the
weight of the car is supported more vertically and the strains on the wheels are reduced.
By tilting the axle backwards the axle is in a more favorable position to resist
jolts and shocks. Any shifting of the wheels from the straight ahead position works directly
against the weight of the car so the tendency is for the wheels to swing back to their original
The Ford axle is tilted backward at the top spring perches at an angle of five and
one-half degrees or 1/4 to 5/16" along the length of the spindle body.
The material used is Ford alloy steel. This type steel is also used in the spindles
and spring perches.
Under test the Ford axle has been twisted, cold, several times without fracturing.
Heat at 1650° F for 1-1/4 hours; cooled to atmospheric temperature.
Heat again to 1540° F for 1-1/4 hours and quenched in soda water.
Annealed to 1020° F for 2-1/2 hours and allowed to cool.
The tensile strength after hardening process is about 76,000 lbs. and after the
drawing process runs up to 125,000 to 145,000 lbs. per square inch. If the axle is bent it is
The wheel axles or spindle assemblies are set between bosses integral with the main
axle body. A hardened steel bolt holds each in place. These bolts are drilled at their heads
and provided with small dust, caps, thus each is a combined oil cup and bolt.
The spindle assembly consists of the wheel axle, steering arm, inner or stationary
cone, also called the ring cone, the outer cone, the steel washer and hex nut. The steering arm
and ring cone are tight fits and must be pressed into place; the arm is held by a hex castle
nut and cotter pinned. In order that the bolt may not slip easily through the tie bar yoke and
steering arm, the hole on the arm for this purpose is lined up carefully after the arm is
secured. The right spindle is threaded left hand and the left hand spindle the opposite way.
Heat treating of all cones 1450° F. for 20 minutes. Ring cones are quenched in soda
water and then drawn in oil at 400° F. for 20 minutes. The adjustable cones are dipped in the
soda water, then quickly immerse4 in the drawing oil. This results in a tougher and more
substantial cone. Being adjustable they must fit more or less loosely on the spindles, so do
not have the solid backing that the larger ring cone has.
These rods, or tubes, are pressed cold from sheet steel and the seam brazed, so
if bent the original strength cannot be restored by straightening. The point of fastening of
the radius rods to the car is a ball and socket joint brazed to the lower crank case.
Prom a ball on the tie rod, a rod is led to the ball arm of the steering gear.
This connecting rod is called the drag link, and it is through this rod that the spindle
assemblies are controlled by the steering gear.
Formerly one of the sockets at the end of the rod was forged from the rod itself
while the other was made and brazed. Now both are forged directly from the rod. They are set
at an angle of 40° to each other.
Construction and Heat Treating of Springs
The leaves are heated separately at 1560° F. for 12 minutes and each is then placed
in a special machine which bends it to the required arc and is then immediately quenched in
oil. The leaf is held between two jaws shaped to the necessary arc and while thus held is
immersed in the oil. Each machine has four such jaws and the operation is continuous. As the
jaws return, bringing the leaf to the surface, they open automatically, the leaf sliding to
a container. After being shaped they are drawn in sodium nitrate at 850° F. Sodium nitrate is
used since it is not volatile at that high temperature.
After cooling they are bolted together through their centers and the clips set in
position. The clips hold the bands together and in alignment so that on a rebound, the whole
spring assembly will act as a unit and not throw the strain entirely on the first or eye leaf.
Spring Tests for Load and Endurance
The Ford spring will stand a load of 2000 lbs. before it is straightened out, and
around 100,000 continuous vibrations before it will break. At 2000 lbs. each leaf is practically
a straight line and therefore rests firmly on its neighbor, supporting it along the whole length
at the same weight.
The test for endurance is performed on a special machine for that purpose. The
spring is held by its ends and the center forced down and back again at the rate of 120 times
per minute. Some springs have stood as high as 130,000 vibrations, but the average is about 100,000.
The point of breaking varies from the center to practically any point of the length.
Although being pierced in the center by the drilled hole, only about one third of the test
springs break at this point.
The parts of the steering gear which are fastened directly to the front axle are
the spindle assemblies which are set between bosses integral with the main axle body. A hardened
steel bolt holds each in place. These bolts are drilled at their heads and provided with small
dust caps, thus each is a combined oil cup and bolt.
The spindle assembly consists of the wheel axle steering arm, inner or stationary
cone, also called the ring cone, the outer cone, the steel washer and hex castle nut. The
steering arms of this assembly extend towards the rear of the car and these arms are fastened
together by a transverse rod called a tie rod. This tie rod is moved crosswise by a drag link.
One end attaches to the right hand end of the tie rod whose other end is attached to the ball
arm at the lower end of the steering column. Movement of this ball arm pulls the steering link
one way or the other, and through the tie rod and spindles the front wheels are turned.
The tie rod is of such length that when one of the front wheels is turned the other
turns also, but to either a greater or less degree than the first one. Regardless of the amount
that either wheel is turned, it will be found that lines through their spindles point to one
and the same point and that this point lies in a line drawn through the rear axle. However, a
stop device located on the inside of the gear case allows the spider assembly to revolve only
a limited distance in either direction.
The construction of that part of the steering gear which is directly acted upon by
the hand wheel consists of a shell on the inside surface of which are gear teeth (36 in number).
This shell is fastened to the upper end of the steering gear column housing and remains stationary.
In mesh with the teeth in this shell are three small pinions, (12 teeth cut on each) which are
mounted on a triangular plate fastened to the upper end of the shaft extending down through
the center of the steering column. The steering wheel carries another small pinion which meshes
with all three of the pinions which are attached to the steering column shaft.
When the steering wheel is turned by hand it revolves the central pinion, and in
doing so causes the three steering shaft pinions to roll around the inside of the toothed shell.
In traveling around the inside. of this shell the three pinions carry with them the triangular
piece on which they are mounted, and the steering shaft is thus caused to go through part of a
It will be realized that if it were possible it would require several revolutions
of the steering wheel and its gear to cause the three pinions to travel all the way around
inside of the shell. It therefore requires a considerable part of a revolution of the steering
wheel to effect any great change in position of the steering shaft. This seduction of motion
increases the force applied by the driver to the road wheels and gives better control of the
direction in which the car travels.
Steering Gear Material
Toughness is more desired than hardness, for the whole mechanism is forced to
undergo, generally, sudden and severe shocks and any brittleness, of the parts would result
in sudden breakage, the only heat-treated parts of the steering assembly being the ball arm
and gear studs and the bushing for the driving gear shaft. The bracket which holds the column
firmly to the frame of the car is of malleable iron. The metal absorbs shocks and vibration
readily, and being ductile, resists breaking to a very great extent. The gears and main driven
shaft are of cold rolled steel. The gear case or internal gear is of bronze, bronze used not
only for the formerly mentioned reasons but because it is easily and accurately machined.
Steering wheel rims are solid rubber 16" in diameter. Steering ball arm---H.R. steel;
planetary pinion gears, driving pinion gear, and drive shaft-cold rolled steel; gear case---bronze.
Overall length of driven shaft 54-5/16". Angle to dash 39 degrees 45". Distance of steering wheel
to dash 29-27/32". Steering post case-pressed steel.
Two separate and distinct brakes are provided. One of these brakes acts on a drum
carried with the transmission gearing and is called the service brake; it is of the external
contracting type and is operated by the right hand foot pedal. The other brake acts directly
on the rear wheel hubs through drums fastened to the hubs and into which brake shoes are
expanded when a pull is exerted on rods which attach to the controller shaft. This wheel brake
is called the emergency brake and is of the internal expanding type.
The principal parts of the emergency brake consist of the steel drums, which are
solidly fastened to the rear wheels, and two shoes which expand inside of each of these drums.
The service brake is carried in the transmission and consists of a band which encircles the
brake drum and of a foot pedal which acts to contract the band through linkage drawn tight
when the pedal is pressed.
The service brake retards the motion of the car through its effect first on the
brake drum and sleeve, then on the universal joint and the drive shaft, then through the rear
axle driving gears and differential to the axle shaft and to the wheels. The differential
serves to divide the braking effect equally between the rear wheels and in this way serves the
purpose of what would be called a brake equalizer were such a device built as a separate part
of the braking system. The division between the rear wheels of the braking effect exerted by
pulling on the hand lever is not determined by any equalizing device, but depends for equal
action on maintenance of correct length of the pull rods.
U.S FORD PASSENGER CAR PRICES
Date Oct. 17, 1922, at a dealer in Conder, S.D.