What You Should Know About a Car Before You Attempt to Drive
By A. HYATT VERRILL
From American Boy Magazine, April 1916 provided by Bobby Ryan, digitized by Doug Frizzle, 2007
THE FIRST STEP In learning to drive an automobile is to master the mechanical details of the car. One may drive for many miles without the least knowledge of the details or construction of the car, or of why a certain operation produces a certain result, but if anything ever happens, a good working knowledge of the essential features of the mechanism will be of incalculable benefit.
Before you attempt to drive a car, study the motor carefully. Ask the agent, or someone who understands the machine, to explain the engine and its operations, familiarize yourself with its various parts, and watch it while it is running idle until you understand just what each and every part and accessory is for, how it works, and what it does. Get a copy of the instruction book issued by the manufacturers of the particular car you wish to master. In a general way, all motors are similar, and certain requirements and attentions are essential to them all in common.
Modern automobile motors are so well built, there are so few external openings, and the moving parts are so well protected and covered that they will operate even when coated deep with dust and dirt; but there is no excuse for a dirty motor and dirt never did an engine any good. If the motor is wiped off frequently it may easily be kept clean with little trouble, and you'll find a clean motor far easier and pleasanter to adjust and care for than a dirty one.
Fig. 1. Shifting Gears.
The Clutch
HAVING MASTERED the motor, next turn your attention to the driving mechanism. This, in most cars, consists of the clutch, transmission gears, propeller shaft, and differential. As these are all out of sight under the flooring of the car, they are usually out of mind as well, and are woefully neglected. As they receive all the strain, jolt, and jar of driving, and since they are exposed to all the mud, dust, dirt, and grit of the road, they receive the hardest usage of any part of the mechanism of the car and the wonder is that they fail so seldom.
Some cars do not have a clutch, but the majority or cars do and it is to these that my remarks must be confined. The clutch, located just back of the motor, consists of a device which transmits the power and motion of the motor to the driving mechanism or gears and is so designed that it may be connected or disconnected at will. When the clutch pedal is released, or in its normal position, the clutch revolves with the shaft of the motor, and carries with it the shaft leading to the gears. When the clutch pedal is depressed and the clutch is "thrown out," the motor revolves freely and the gear shaft connecting with the rear wheels remains motionless. Thus, with the clutch "out." there is no connection between the motor and the driving mechanism of the car, whereas with the clutch "in," the engine is connected directly with the gears and driving mechanism and so moves the car. Aside from keeping the various grease cups and lubricating devices of the clutch supplied with lubricants, the clutch requires little attention.
The Transmission
BEHIND the clutch is the transmission or "gear box" (in standard cars), and to many this is a deep and unfathomable mystery. While to the lay mind the transmission of a three or four-speed car is complicated, and space will not permit a full and detailed explanation, yet its principles are simply and easily understood, and if these are mastered and the gears are kept properly lubricated, according to the directions in the instruction book, the average driver or owner need give them but little thought. The majority of cars are provided with gears known as “selective”. Fords and some other cars have transmissions of the "planetary" type. Although the action and operation of the selective and planetary gears are quite distinct, yet their purpose is the same; which is to provide a means of increasing the power and decreasing the speed of the driving wheels of the car or vice versa.
The gears may be operated either by means of foot petals and a lever, as in the Ford, or by a hand lever as in the various standard cars with selective transmissions. In the case of the former, the gears may he changed or "shifted" without disengaging the motor from the transmission, for the gear wheels themselves are always engaged and are made to drive, or are left running idle by means of friction-bands which thus serve as a sort of clutch. In the case of cars with the standard selective gears, the various gears are moved back and forth upon their shafts, and in order to accomplish this without undue wear and tear on the gears, or grinding, and jerking as the speeds change, the motor must be disengaged from the gears when shifting from one speed to another; it is to enable the operator to do this that the clutch is provided.
The majority of selective gears have three speeds forward and one reverse, but some have four forward speeds and one reverse. In each and every ease, the operation is very similar and while the operating or gear-lever may be on the right or left side of the car or in the center, yet it is always arranged to move in a lateral and longitudinal direction to change the gears from one speed to another. The commonest method is for the gear-lever to move in two parallel guides or slots with an opening or "gate" from one slot to the other near the center, forming an "H" (Fig. 1.) When the lever is in this central opening or "gate," the gears are all disengaged, and the clutch may be thrown in without moving the car. This is known as the "neutral" position, and is the position to which the lever should always be set when the car is stationary. By moving the gear lever to one end or the other of the two slots, the various gears are meshed and the several speeds are obtained.
The forward end of the inner slot may be reverse and the opposite end the first or lowest speed (Fig. 2-B) or vice versa (Fig. 2-A) ; the two ends of the outer slot will then give the intermediate or second. and the third or direct drive, also known as "high." Sometimes the inner slot gives the second and third speeds and the outer slot the low and second (Fig. 2-C D) ; for car builders have not yet standardized the gear-shifting movements and different makers use different arrangements. In every case, however, low speed and reverse are at the opposite ends of one slot, and second and high are at the opposite ends of the other slot, with the second speed at the same end of the slot as reverse, and the third or high at the same end as first. Thus, if the reverse is in and forward, high will be out and back, and for this reason if you once learn the position of any certain speed on a car you can readily know the position for the other speeds. In most cars you will notice that the position of the various speeds is marked on the plate at the base of the gear lever as on Fig. 2. When the lever is in the slot marked one, the gears are in first; when in two, in second; when in three, in high; when in R, in reverse.
In some cars, the slots do not show at the base of the gear lever, though the positions are marked, but the "H" is there just the same and the gears are shifted in exactly the same manner. Sitting in the driver's seat, you can determine the position of the gears by feeling the gear lever. If the lever slips freely from side to side, it is in the cross bar of the "H" or in neutral, if it will not, moving it forward or back will put it in neutral and it may then be shifted into the desired position.
In shifting the lever from one speed to another, it is obligatory to throw out the clutch, as before mentioned, and as a rule it is also necessary to "go through" the speeds in regular order. Thus, from first the lever must be shifted to second and then to high, instead of directly from first to high; and when shifting from speeds in one groove to those in the other, the lever is swung out or in through the neutral gate (Fig.1). This may sound somewhat complicated, but a glance at the accompanying diagrams will make it plain, it is usually advisable to start the car on the lowest speed, and then shift through to second and finally to high, as the machine acquires momentum. This does away with a great deal of the rack and jar attendant upon getting a car in motion and which would occur if the car were at once started on high or direct drive. Many cars, however, may he started on level ground on second speed without injury, thus obviating one shift, but until the driver is thoroughly experienced and familiar with his car, it is wiser to start on the lowest gear.
The principal attention which the owner or driver should give to the transmission gears is to keep them well lubricated. The exact grade of grease or oil recommended by the manufacturer the car should be used, and the gear-case should always be kept well filled through the opening provided for this purpose.
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Universal Joints
FROM the gear or transmission case, the propeller shaft (I am assuming that shaft-driven cars are under discussion) extends to the rear axle. Somewhere upon this shaft there is a joint or coupling known as a "universal joint." This Is a joint so arranged that the shaft is free to move in almost any direction, thus relieving it of strain when the car rides over unequal spots or sways sideways (Fig. 3.). If the shaft were rigid, it would either be bent, or the transmission or other parts of the machine would be thrown out of alignment. Moreover, the transmission and motor is usually considerably higher from the ground than the rear axle, and hence the propeller shaft must run at an angle from the driving gear to the axle; therefore, in order to transmit the rotary motion through this crook or angle, a universal joint is necessary. Universal Joints should be kept well greased and should be protected from dust, dirt, and grit by keeping them covered with a leather boot. Many owners of cars imagine that this boot is designed and provided for the purpose of retaining grease, and accordingly they pack it full of lubricant. However, the purpose of the boot is not to keep grease in, but to keep dirt out, The joint should be carefully and thoroughly cleaned and greased, and the boot cleansed and replaced at frequent intervals. Aside from this, the universal will seldom require any attention, unless the bearings, blocks or other parts become worn or loose when they should at once and be tightened up.
IF YOU DESIRE information concerning any particular make of motor car in which you are interested, address "The Automobile Editor, THE AMERICAN BOY, Detroit, Mich.," and he will see to it that the information is supplied to you.
The Differential
WHERE the propeller shaft joins the axle, there, is an enlarged portion of the axle housing, and within, this Is the device known as the "differential." The differential consists of certain gears which very in their design and arrangement in different cars, but which are provided for the purpose of distributing the motion and power of the motor to the two wheels equally. The necessity for such a device will be readily understood when it is remembered that in turning a corner the wheel on the outer side must cover a far greater distance than that on the inner and hence it must make more revolutions— or it must slip on the ground if it is connected immovably to the same shaft as the other wheel. In the case of a horse-drawn vehicle, where the wheels are free to revolve independently upon their axle, no difficulty is encountered, but in the automobile, where the wheels are connected to the axle which drives them, provision must be made to permit one wheel to revolve faster than the other white still driving the car. This is exactly what the differential accomplishes. It is not necessary to enter into a detailed explanation or discussion of the technical side of differential construction. In each- case, the axle of the car is in two pieces, and the inner end of each piece is provided with a gear which is driven by means of gears in the differential, and which are in turn operated by a gear upon the extremity of the propeller shaft. The arrangement of these gears permits either section of the axle to revolve independently of the other while driving both. provided that there is any traction or resistance offered to both wheels. If, however, one wheel is resting on the ground and the other is lifted clear— as when the car is jacked up— and the motor is started, the transmission gears being in mesh, then the wheel free of the ground will revolve while the other remains stationary.
The Steering Gear
THE MOST IMPORTANT PART of the car. so far as the safely of its occupants is concerned, is the steering gear (Fig. 10.) A deranged, loose, weak, or broken steering gear may result in a fatal accident without the least warning. Time and again we read of accidents which were caused by a defective steering mechanism, and yet the average driver gives very little attention to this vital part of his car. You should frequently examine the steering gear and see that it is kept properly lubricated, that there is no undue looseness, and that it does not "jam" or bind. All steering gears have adjusting devices for taking up the wear, and you should make use or these and keep the steering mechanism just tight enough to give perfect control of the car. At the same time, it must not be so tight as to make it difficult to turn the wheels.
Although not strictly a portion of the steering gear, yet the proper steering of a car depends a great deal upon the condition of the pivoted hubs of the front wheels, if the bearings are worn and loose, or dry and stiff, it will be impossible to steer the car properly and these parts should be inspected and cared for as carefully as the steering gear proper.
The importance of keeping the front wheels in alignment is often overlooked, even by experienced owners and drivers. If the wheels are out of line, vertically, (Fig. 4.), you may be sure there is a badly worn bearing, pin, or spindle on one or both of the wheels, or that the axle or a spindle is bent. If, on the other hand, the wheels are out of line horizontally, the fault may be remedied by adjusting the distance rod between the wheels. It is a far easier matter to determine a vertical than a horizontal fault in the alignment, but the latter may be easily ascertained by using a string or two light sticks or rods, each a little more than half as long as the distance between the wheels.
To align the wheels, turn one wheel until it is parallel with the frame and in line with the rear wheel on the same side. Place one rod against the inner rim of the wheel, directly in front of the hub, and place the other rod against it and with its end touching the inner rim of the other wheel. Mark a couple of lines across both rods (Fig. 5) and proceed in the same way to measure the distance between the two wheels from rim to rim, directly back of the hubs. If you find the front rims are farther apart than the rear, you must lengthen the distance between them by screwing out the distance-rod, if in the rear of the axle; or by screwing it in if it is in front of the axle. If, on the other hand, the front rims are nearer together than the rear, the operation must be reversed. If there is a little play in the various joints, bearings, etc.. adjust the wheels so that the front edges are slightly nearer together than the rear, for when running with a load there will be a tendency for the wheels to spread apart at the forward edges. Don't hesitate to take plenty of time and to use great care in adjusting the wheels. If they are out of line, they will cause undue wear on the tires,
Brakes
LAST, but by no means least in importance, are the brakes. As a rule, brakes are woefully neglected and, as a result, they give out or fail without warning, and at the most critical times. If you examine the brakes, you will find that there are usually two sets—one operated by a foot pedal and known as the "service brake." and the other operated by a hand lever and known as the "emergency brake." The ordinary form of brake consists of a metal band, so arranged as to grip a metal drum on the hub of the rear wheel. The band may be of metal only, or it may be faced with material composed of woven asbestos and wire. In some cars, the service brake is within the hub-drum, and grips the latter by spreading or expanding, while the emergency brake is on the outer circumference of the drum, and grips it by closing or contracting. In other cars the reverse arrangement is used.
Where the brakes are of metal, little can be done except to keep them properly adjusted, but if they are lined with friction material, the linings may be renewed when badly worn. Brakes should be so adjusted that either set will hold the car on a steep hill, for if you are obliged to depend upon both sets together and one brake fails, the other will not hold the car, and disaster may result. On the other hand, the brakes should never be so tightly adjusted that they bind when not in use. If the rear axle is jacked up and the wheels are turned by hand, it is very easy to determine whether the brakes bind or not. Brake bands should be kept free from grease or oil, and the various pins and joints should be kept well oiled.
When using a brake, never jam it on suddenly and lock the wheels, even in an emergency. If the wheels are locked, the car may slide or skid, whereas if the brakes are put on gradually, using first one and then the other, the car may be brought to a standstill more quickly and with far greater safety. Locking the brakes and letting the rear wheels slide is especially hard on tires.
Throttle and Spark
ALTHOUQH the speed and power of the car may be regulated to a certain extent by means of the gears, yet the primary method of regulating speed and the one upon which you should largely depend, is by spark and throttle. The throttle acts upon the carburetor, and allows a larger or smaller charge of fuel to enter the motor, according to whether the throttle is open or closed. The spark lever acts upon the magneto or commutator, and causes the ignition spark to occur earlier or later in relation to the position of the pistons in the cylinders. This is known as "advancing" or "retarding" the spark, and the niceties of good driving depend largely upon the operator's skill and knowledge regarding spark control. Although a motor will run faster, cooler, and more economically with an advanced spark, when on level ground and with open throttle, yet under many conditions the spark should be retarded in order to secure the best results. In addition to the hand levers which control the throttle and spark, many cars are provided with foot pedals which act upon either the throttle or spark, or both. The ordinary arrangement is to have both spark and throttle levers upon the steering-wheel column, with an additional or supplementary throttle lever which may be operated by the driver's foot. This Is known as the "accelerator," and enables the driver to open the throttle while leaving both hands free to steer, sound signals, or operate brakes and gear-shifts. As the spark lever is used far less often than the throttle, a foot control of the spark is not essential and is seldom provided.
An article on “Learning to Drive the Motor Car," will follow in the April AMERICAN BOY.
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