Brake (device)

“ 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. ”

“ An automobile is always equipped with two sets of brakes, as they are required by law. The functional action of the brakes is to check the motion of the car when the driver wishes to stop or reduce the rolling speed. The service brake usually operates on the external surface, or on the outside of the drum flange, and is connected to the right foot pedal through a set of linkage. The emergency brake operates on the internal surface of the drum, and connects through linkage to a hand lever operating on a notched quadrant. ”

“ As every car is equipped with two distinct sets of brakes, drivers should learn to use first one and then the other on long grades, and this may be helped out considerably by using the motor as a brake—that is, by cutting off the ignition and allowing the machine to push the engine under compression, and even more by engaging a lower gear before cutting off the ignition, so that there is a greater leverage obtained to retard the car. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ In 1891 a so-called high-speed air brake was perfected, this brake being really a modified quick-action automatic brake. This modification consists of the addition of an automatic pressure-reducing valve connected with each brake cylinder. In the high-speed air brake as applied when the train is running rapidly, the highest possible pressure is applied at once to the wheels, but this pressure is lessened by the automatic pressure-reducing valves as the speed diminishes. This method of applying the brakes is the most effective way of getting the full benefit of their stopping power. ”

“ In one type of electric brake the active braking force is taken from an axle of each car. A small friction-drum is made fast to the axle. Another friction-drum hung from the body of the car swings near the axle. If, when the car is in motion, these drums are brought in contact, that one which hangs from the car takes motion from the other, and may be made to wind a chain on its shaft. Winding in this chain pulls on the brake-levers precisely as if it had been wound on the shaft of the hand-brake. The sole function of electricity in this form of brake is to bring the friction-drums together. ”

“ 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. ”

“ 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. ”

“ If, when a car is running, the controlling switch is turned to cut the current off, the effect will be that the speed will gradually reduce; but if it is desired to effect a sudden stop, it becomes necessary to check the headway by means of a brake. For this purpose the hand brake ordinarily used on all types of cars is employed, but magnetic brakes are also used in some cases. Fig. 20 shows a car truck equipped with two motors and magnetic brakes, one on each axle. ”

“ The service brake should be kept in such condition that it will bring the car to a stop within a reasonable distance at any car speed, and it should be understood by the driver that the emergency brake is not intended to be used to help out the service brake which holds poorly when a quick stop is desired. ”

“ The brake shoved on with a jerk at every stop jars everybody in the vehicle, and has been known, not once, but often, to actually chuck people clean out of the vehicle, both behind and in front, besides bringing the horse into his collar with a painful galling of his shoulders. On a level place the brake should never be used to stop the vehicle. After the vehicle has been stopped, particularly if it be a heavy one, the brake may be put on and left on until the next start is made—this as a measure of precaution.
Never put on the brake in any case with the whip in the right hand. ”

“ 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. ”

“ 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. ”

“ Usually the brake is a simple lever acting on a brake pulley at one end, whilst at the other it is regulated by an inclined bracket connected with the starting handle. When the handle is pushed forward, the brake lever is lifted; when the knocking-off takes place the end of the brake lever drops and the leathers come in contact with the pulley, stopping the loom. Additional brake power may be made by altering the leathers or weighting the brake lever. ”

“ To apply the brake, first release the clutch by pushing on the clutch pedal, then push down or forward on the brake pedal with the right foot gently but firmly until the car is stopped. After removing the foot from the brake pedal the brake will be released automatically by means of a spring. Use the brake gently to save discomfort to the passengers, wear on tires and the machine in general. Do not run close to the point where the stop is to be made and then jam the brake on hard, but begin to apply it early and bring the car to a standstill gradually. ”

“ 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. ”

“ The approach of the corves toward the pit mouth was signaled by a bell, brought into action by a piece of mechanism worked from the shaft of the engine. When the bell sounded, the brakesman checked the speed by taking hold of the hand-gear connected [118] with the steam-valves, which were so arranged that by their means he could regulate the speed of the engine, and stop or set it in motion when required. 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. ”

“ Every motor vehicle other than a motorcycle shall have brakes which can be easily operated by the driver when in his driving position. These brakes shall be capable of performing the following three braking functions:
(a)
A service brake capable of slowing down the vehicle and of stopping it safely, rapidly and effectively, whatever its conditions of loading and whatever the upward or downward gradient of the road on which it is moving ”

“ 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. ”

“ Section 5.—BRAKES AND RETARDING APPLIANCES. To retard or arrest motion (revolving or rectilinear) .
35. Strap and lever brake. The strap is usually faced with wood or leather, but sometimes is used without either. Wood is liable to become noisy. Leather gives the best grip. Iron upon iron, or wood upon iron is not safe if liable to become oily or wet.
36. Block and lever brake. Wood or cast-iron blocks are used.
37. Compound block and lever brake; avoids putting cross strain on the shaft—used on winding engines, &c.
38. Internal toggle brake, employed for friction clutches. ”

“ They ran until the friction of the bearings was sufficient to stop them. This occasioned, however, rapid wearing and too great a loss of time. The best material for a brake consists of soft wood into which shoe pegs have been driven, and which is thoroughly saturated with oil. The wooden disks referred to just above are of the same construction. The center of oscillation ought to be in the central plane of the brake as well as that of the pulley, but the preference is given to the pulley. ”

“ When, however, the drum revolves in the opposite direction, the action of the brake is opposed, instead of being assisted, by the motion of the drum. As a consequence, this particular form of brake is not adapted to hoisting drums that revolve in opposite directions at each alternate hoist. Differential brakes are not generally used.
Fig. 27
45. Power for Brakes.—For small drums and light loads, the brakes are usually applied by hand power through suitable lever connections. The force that a man can exert can be multiplied indefinitely by levers and combinations of levers ”

“ The breeching is, or ought to be, considered indispensable in a hilly country, even with light vehicles, and is a proper precaution in all cases where women or children act as coachman.
Brakes are a French invention, and might be supposed to come under much the same strictures as the breeching. But while a breeching is useful and never out of place, except perhaps on the leaders where horses are driven in front of each other, the brake is so often misused, with consequent damage to the horse, the harness, the vehicle, and the skill of the driver, that it almost deserves a chapter by itself. ”

“ Both sets of brakes should be carefully examined to see that the lining is not worn too thin and that the different pins and clevises of the brake linkage are not worn so as to be weak and likely to give away in touring under extraordinary pressure. Often in touring one comes upon unexpected grades, some of them miles long, and the tourist should be prepared for prolonged and extraordinary service. ”

“ He further maintains that the braking power of the ordinary car is extremely low, due, sometimes to the design of the braking system and sometimes to the failure of the owner to adjust the brakes properly. He states that a car equipped with an efficiently constructed system of brakes on four wheels may be stopped from a speed of 30 miles per hour in 36 feet, whereas an average car in the hands of the average motorist will require from 100 to 150 feet. He thinks the brake should be powerful enough to lock the wheel through which it acts. ”