Emergency brake

“ The amount of pressure applied at the brake pedal depends upon the distance in which the driver desires to stop the car. Before allowing the clutch to engage after the car has stopped, move the gear shift lever to the neutral position. If the car is to stand apply the emergency brakes. If the engine is to be stopped speed it up by opening the throttle just before turning the ignition switch to the position “off.” If the weather is cold use the choke when stopping the engine or set dash adjustment to give a rich mixture. ”

“ Band brakes are usually lined with leather, to increase the friction between the band and the drum, and this often gives rise to troubles in the burning of the leather when the brake is applied for a considerable period, as in the descent of a long hill. The emergency brake has advantages in that it operates through the friction of metal against metal, but excessive heat from continued application may be enough to melt the metal and fuse together the shoe and drum. ”

“ It will be well to place a stone or block back of the rear wheels before cranking the motor as the vibration of the engine may jar the emergency lever loose. In starting again, release the clutch, put lever in first speed gear, accelerate strongly, release the emergency brake and at the same time let the clutch engage. ”

“ On a slight and straight hill it is all right to go234 down on high speed, simply shutting off the ignition so that the engine will act as a brake, the foot brake being used if necessary; but on a steep hill it is far wiser to shift into second-speed or even first-speed gear before attempting to descend. The engine will exert a powerful braking force in low-speed gear. Besides, the running and emergency brakes are to be used alternately, so that on a long hill the brake linings will not be burned up. Of course the clutch must be left engaged to secure the braking effect of the engine. ”

“ While the automatic brake had thus obviated the most important defects of the old or straight air brake, and came into general use upon passenger trains throughout the country, it was found, in practice, upon long freight trains, that the air from the auxiliary reservoirs did not act with sufficient promptness upon the brakes of the rear cars, whee a particularly speedy action was required, and that it would be necessary to devise some other means for cases of special emergency. ”

“ Of SP’s road fleet of 2,100 units, 1,800 units, according to the chief mechanical officer, are equipped with dynamic brakes. SP locomotives are designed such that when the train brakes are applied in emergency, an interlock will nullify the dynamic braking. According to SP’s chief mechanical officer, the system is designed in this manner "...to prevent train handling problems in the case of a break in two [a separation of two cars] and to prevent wheel slide because of excessive braking which would be the combination of the electric [dynamic] braking and the independent brake...." ”

“ Again, if the air-pressure in the brake-cylinders is so high, and the adjustment of the levers such that an instant application of the full pressure will stop the rotation of the wheels, and cause them to slide on the rails, the stop will take longer than if the wheels continued to revolve. The maximum [199] braking effect is obtained when the pressure on the wheels is as great as it can be without causing them to slide, and it may happen that a quicker stop can be made by putting the engineer's valve to the service-stop position than by trying to make an emergency-stop. ”

“ Upon a long train of this kind, composed of 30 to 50 cars, a demand was made for quicker action in cases of emergency than had yet been contemplated, although, for ordinary work, such as checking the speed of a train while running, holding it at a slow speed on a down grade, and also for making the ordinary station stops, the automatic brake was still sufficient, and produced satisfactory results, even in the equipment of long and heavy trains. ”

“ In the power braking method, the locomotive brakes are released immediately after making an automatic airbrake application, which allows the car brakes to slow the train or bring it to a stop and eliminates the locomotive independent brakes. The Safety Board concludes that the discrepancies found in the brake system of Amtrak train 66 after the accident did not affect the apprentice engineer's ability to slow the train because the independent brake was not used in the power braking method. ”

“ 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. ”

“ 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. ”

“ Educate your men to feel that neglect of this wise precaution is just as mortifying as to appear in public without clothes. In shoving long cuts of cars without using air, get your brakemen and switchmen to feel a pride in setting a hand brake on the end car to take the slack and save the jerk on the drawbars. Work for the old-time feeling of chagrin that came to the calloused-armed passenger brakeman, in the days of Armstrong brakes, when he did not go after them soon enough and let his train run by the station. The men are not to blame for this loss of pride and interest. ”

“ 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 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. ”

“ 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. ”

“ To apply the brakes he turns the handle to such a position as to allow air to escape from the train-pipe; to release, he turns it to allow air to pass from the main or locomotive reservoir into the train-pipe, and thence into the car-reservoir. It is hardly necessary to say that the operation of the brake, which has been described for one car, is practically simultaneous throughout the train. The brakes on the driving-wheels of the engine are also automatically applied at the same time as those of the cars and the tender. ”

“ 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. ”

“ In this connection it is well to keep in mind that on long grades considerable braking may be done by cutting off the ignition and allowing the car to turn the engine over in high or intermediate gear. Keeping the car down to a rather low speed in this manner will also be found to save burning up the brake linings. ”

“ 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. ”

“ These runnings away of electric trams called for increased attention to the question of brakes, which, though they will always hold a car on a stiff incline on dry rails, yet when the track is greasy they introduce an element of danger by reason of their very power. They skid the wheels, which is always a source of great danger. In such cases safety lies in relaxing the pressure, but it needs a wary brain and firm nerves to ease off the brake at all when the car has already bolted. ”

“ As a train moving at the rate of 50 miles an hour makes over 70 feet per second, a train of 50 cars would run half a mile before the brakes could be applied to the rear car. So, too, if the rear end of the train became detached from the forward end by the rupture of the train pipe or couplings, the brakes could not be applied at all, since the compressed air admitted to the train pipe by opening the engineer's valve would escape into the atmosphere without operating the brakes, or, if the brakes were already applied, they would be instantly released when such rupture occurred. ”

“ Perfect brakes are also indisputably promotive of safety in working traffic and in compensating for unavoidable irregularities. With the usual amount of braking power, a train at 50 miles per hour may not be stopped within 900 or 1200 yards. An instantaneous brake is not of course what is wanted; on the contrary, a length of 200 yards appears to be the shortest desirable space within which a train at 50 or 60 miles per hour should be stopped, so that the process of retardation should not be accompanied by risk of carriages riding over each other, or of violence to the passengers. ”

“ 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. ”

“ In order to hold speed steady on a descending grade, the force of gravity must be balanced by the sum of train resistance and brake retarding force. The heavier the grade, the lower the effect of train resistance; and the more brake must be used. ”

“ The rim of the wheel is rapidly heated by the friction [200] of the brake-shoe, and the unequal expansion of the heated and the unheated parts of the wheel causes a fracture. This is why so many broken car-wheels are found at the foot of grades—of all places the worst for such an accident to happen. With "straight air," that is, with the pressure from the main reservoir, or the air-pump, going directly to the brake-cylinder, the engineer can apply the brakes to all the wheels of his train simultaneously, and with great delicacy of graduation ”

“ It is the opinion of many competent men that the above accident would not have been so disastrous if the train had been fitted with an automatic brake. It had what is called a continuous vacuum brake, which is effective enough so long as the coaches do not become separated. When such separation occurs, the wheels are no longer held in check. With the automatic brake, on the other hand, which is adopted by many of the leading railway Companies, the wheels are immediately acted upon, if by any means the coupling between the carriages should be broken. ”

“ This is not only very injurious to rolling stock, the wheels of which are flattened at the points which slide, but, as has long been practically well-known to those whose business it is to run locomotives, when once the wheels begin to slide the retarding power of the brakes is seriously diminished. In order, therefore, to secure the maximum of retarding power, the pressure of the brake-blocks on the revolving wheels should be very great when first applied, and just sufficient not to slide them; and should then be diminished, pari passu with the momentum of the train, until it wholly stops. ”