Braking

“ Perhaps the most serious danger in the car mechanism is the brake. Mr. Harold F. Blanchard writing in Motor (New York) , argues that more than half, probably as much as 90 per cent of all motor accidents may be eliminated by making the stopping ability of motor vehicles a maximum instead of 25 to 50 per cent, as is now the rule. He would have brakes put on all four wheels and claims thereby the braking power of the machine can be more than doubled. ”

“ The matter of brakes is coming up for more attention in these days of high speed, heavy cars and crowded roads, and the total available braking power, which has hitherto been but partially taken advantage of, must be fully utilized. ”

“ Steering and braking should go together.
On some of the steep mountain roads, which, because of their length and relative grade with the bottom of the canyon, appear to be nearly level, it is impossible to hold the car with the brake alone. It is customary in such cases to assist the brake with the engine; unless the driver is very expert at changing gears the engine should be put in low, or intermediate, depending on the steepness, at the top of the hill, then with brakes and clutch the car may be controlled and kept to a safe speed. ”

“ The ignition may be switched off or on as the occasion requires. Switching it off gives greater braking power. The clutch must be left engaged, and the brakes may be used to help. It is well to use first one brake and then the other in descending long grades, as too long an application of one will cause it to heat and burn the friction material. ”

“ A. The air brakes should be released and a sufficient number of hand brakes applied to hold the [Pg 242] train. Never rely on the air brake to hold the train for any length of time.
200. Q. Why is it dangerous to repeatedly apply and release the brakes without giving time for the auxiliaries to fully recharge?
A. As time is required to charge the auxiliaries, the feed groove in the triple valve being small, if the brakes are repeatedly applied and released without giving time to recharge, the braking power will be lost. ”

“ As the speeds result from the tightening of brake bands on the drums, there is no danger of damaging the gears by mishandling, for the brakes will slip before the teeth will give way. The brakes, which are leather-lined strips of steel, require attention from the wearing of the leather, and the slipping that results from oil working in between them and their drums. No foot clutch is necessary, for the tightening and loosening of the brake bands is controlled by a lever; in some designs, the reverse is applied by means of a foot pedal, and this may be used in braking the car.
[Pg 139]
Fig. ”

“ The tire brake has fallen into disuse, rim brakes and internal hub brakes being usual. The retarding force that can be applied by a brake is limited by the possibility of skidding the wheel. In riding at uniform speed, without acceleration, the greater part of the load is on the rear-wheel; but as soon as the brake is applied to cause retardation the wheel load distribution is altered, more load being thrown on the front wheel. Thus the most powerful brake is one applied to the front wheel. On the other hand, a front-wheel brake often sets up an unpleasant vibration of the front fork. ”

“ When running on any speed, if you allow the car to gain impetus and then put the change-speed lever in neutral position, the car will travel on in the same manner as a free-wheel bicycle, the action of the gear being neutral temporarily disconnecting the engine and gear.
If you see an obstacle in the road do not go up to it at full speed and suddenly put on the brake. The sudden application of the brake will hasten the end of the life of your tyres—and if you are not driving on non-skid tyres a bad accident may be the result if the road is at all wet. ”

“ Every car carries at least two brakes of band pattern—one, usually worked by a side hand-lever, acting on the axle or hubs of the driving-wheel; the other, operated by the foot, acting on the transmission gear (see Fig. 48) . The latter brake is generally arranged to withdraw the clutch simultaneously. Tests have proved that even heavy cars can be pulled up in astonishingly short distances, considering their rate of travel. ”

“ If the foot-brake had burned, as possibly it might, the compression of the gas in the cylinder could have been made to act as a brake. The steering-gear was in perfect order, which was the most important consideration in the circumstances, and I felt that I was undertaking a responsibility which the car and I together were well able to carry out. But as I thought that amateurs were likely to be alarmed if they knew what had happened, I naturally kept my knowledge to myself. ”

“ The simplest way of applying a brake is by muscular force, exerted through a hand or foot lever or through a screw, by which the brake block is pressed against the rim of the wheel or the band brake tightened on its drum. This method is sufficient in the case of most road vehicles, and is largely used on railway vehicles. But the power thus available is limited, and becomes inadequate for heavy vehicles moving at high speeds. ”

“ Connected with the fly-wheel was a powerful wooden brake, acting by pressure against its rim, something like the brake of a railway-carriage against its wheels. On catching sight of the chain attached to the ascending corve-cage, the brakesman, by pressing his foot upon a foot-step near him, was enabled, with great precision, to stop the revolutions of the wheel, and arrest the ascent of the corves at the pit mouth, when they were forthwith landed on the “settle board.” ”

“ The brakes used in controlling the speed of an automobile may be as many as four in number, and there should be at least two, for on them depends the safety of the car. Brakes are of two types, expanding and contracting, and usually operate through the friction between a drum and a band that surrounds it, or blocks that press against its inner surface. ”

“ Auxiliary front wheel brake, when used in conjunction with service brake, must be applied with caution, especially on wet, muddy, or slippery roads.
(2) After passing through water, the brakes should be set slightly, and the vehicle operated for a short distance, until sufficient heat has been generated to dry the brakes.
c. Avoid Low Gear Operation. Always operate vehicle in highest gear possible, consistent with tactical situation, speed required, power required, and kind and nature of road substance, to prevent overheating of engine. ”

“ Brakes.—Next to trustworthiness in axles, wheels, and steering gear the sufficiency and certainty of action of the brakes are of the utmost importance. So long as the axles do not break and the steering gear steers, an expert driver can rub along with very poor brakes until familiarity with risks and dangers leads him into a smash, or until some very near squeak makes him shudder when he thinks about it after he is in bed and the light out ”

“ We are aware that it is the habit of some drivers to do what is known as 'drive on their brakes'—that is to say, rush up to an obstacle at full speed and then rely upon their brakes to prevent them from dashing into it. However brilliant it may appear to the uninitiated, the practice cannot be too strongly condemned; for not only does an exhibition of this sort try the nerves of the passengers on the car—however seasoned they may be—but it also produces a bad impression on the public, who, not appreciating the control the driver has over his vehicle, marvels at his apparently narrow escape. ”

“ Caution.—After you have set the gears for starting, and before you release the clutch pedal, always reach and make sure that the emergency brake lever is in the neutral position. New drivers invariably forget to do this, which results in severe strain on the bearings, and causes them to get loose; the average brake band will not stand more than fifteen to twenty minutes of continuous contact before it burns or wears beyond the point of usefulness. ”

“ The brake is of course of a totally different kind from that in ordinary use, which would be of no service whatever on such inclines, as the wheels, even if the brake were so powerful as to stop their revolution, would slide down the hill by the mere force of gravity. Here, however, the brake consists in an ingenious adaptation of the means which are employed in driving the engine. ”

“ During a stop something may happen to the brakes so as to make them quite ineffective, or a portion of the brake mechanism may have broken. The driver who perhaps before luncheon has ascertained that his brakes are acting perfectly, after luncheon may start off in the same supposition, and perhaps not discover his error until, relying on his pedal brake to stop him in traffic, he finds that it has no effect, with the result that he probably goes through the back of a brougham. ”

“ Mechanical brakes, worked by springs, friction wheels on the axle, chains wound on drums, or other mechanical devices, or by the force produced when, by reason of a sudden checking of the speed of the locomotive, the momentum Railway power brakes. of the cars causes pressure on the draw-bars or buffing devices. (2) Hydraulic brakes, worked by means of water forced through pipes into proper mechanism for transmitting its force to the brake-shoes. (3) Electric brakes. (4) Air and vacuum brakes, worked by compressed air or by air at atmospheric pressure operating on a vacuum. ”

“ It is now universally held that the brake, both for freight and for passenger service, must be continuous; that is, it must be applied to every wheel of every car of the train from some one point, and ordinarily that point must be the engineer's cab. With the valve of an efficient continuous brake constantly under his left hand, the engine-driver can play with the heaviest and fastest train. ”

“ Don’t, then, subject your bearings to an unnecessary strain by forcing your motor to labor as it must, if too steep a hill is taken on too high a gear. See that your hand brake can lock your wheels. On a five-mile grade one brake may burn out, and on most cars in this country the hand brake is next to worthless from lack of use and care. Letting the engine act as a brake is a good practice on long descents.
On going through sand or mud that looks as if it might stop you, change into a lower gear and don’t lose your forward momentum. It is easier to keep a car going than to start it again. ”

“ When a load is lifted, work has to be done in overcoming the action of gravity and the friction of the mechanism; when it is lowered, energy is given out. To control the speed and absorb this energy, brakes have to be provided. The Brakes. hydraulic crane has a great advantage in possessing an almost ideal brake, for by simply throttling the exhaust from the lifting cylinder the speed of descent can be regulated within very wide limits and with perfect safety. ”

“ As every revolution of the wheel, B, corresponds to one meter, the number indicated by the counter represents the depth. Upon the axle of the winding pulley there is a break pulley, p. The brake, f, is maneuvered by a lever, L, at whose extremity there is a cord, C, which is made fast to the carriage, A. When, during the motions due to rolling, the tension of the steel wire that supports the lead diminishes or increases, the carriage slightly rises or falls, and, during these motions, acts more or less upon the brake and consequently regulates the velocity with which the wire unwinds. ”

“ It then becomes impossible for a driver to run his train in ignorance of any defect in his brake apparatus because such defect at once discloses itself by applying the brakes and stopping the train. Thirdly, that each vehicle shall carry its own brake power in such a manner that the destruction of the brake apparatus on one or more of the carriages shall not affect the efficiency of the brakes upon any of the others. No continuous brake which does not comply with such conditions can ever be satisfactory.--The Engineer. ”

“ In this statement we find a list of accidents which have been avoided by the use of the brake, and these accidents are classified under different heads, such as Collisions, Obstacles on the Line, Rolling-stock not removed in time, and so forth. Upwards of forty disasters have been clearly avoided by the prompt use of the brake. On the other hand, the brake itself will sometimes get out of order and refuse to act at the critical moment. ”

“ Do not wait until you are half way down the hill before finding out that it is too steep for the brakes to hold the car. Make up your mind before starting to descend and shift to first gear if necessary. Do not allow the brakes to get in such condition that they will not hold to the best of their ability. Never descend the hill at a high rate of speed no matter how safe it looks. Brakes do not hold as well when the car is going fast as they do when it is moving slowly, nor will they stop a car as quickly going down a grade as they will going up. ”

“ When from any cause it is desirable to have the brake inoperative on any particular car, the four-way cock is turned to an intermediate position, which shuts off the brake-cylinder and reservoir, leaving the main brake-pipe unobstructed to supply air to the remaining vehicles. ”

“ This must be done quickly, otherwise the car will start to back down the hill. With some cars it may be found easier when starting from a standstill on a steep hill, to apply the foot brake, release the emergency brake, engage the clutch while the foot brake is released gradually, at the same time feeding gas to the engine with the hand throttle. Do not attempt to climb steep hills until you have thoroughly mastered shifting gears on the level.
Descending Hills—When descending slight grades throw off the ignition switch and leave the gear lever in high speed with the clutch engaged. ”