It is sometimes necessary to use water to keep the brake wheel cool.
Out of the corner of his eye, he saw the brake lights of the woman's car as she drove down the driveway.
In some cases nothing more is required than to attach an engine and brake-van (" caboose ") and despatch the train; but if, as will happen in others, a further rearrangement of XXII.
Poncelet (1788-1867) invented a form of Prony brake which automatically adjusted its grip as µ changed, thereby maintaining F constant.
They are then cut direct from the head and the bark is easily removed by drawing the rods through a bifurcated hand-brake of smooth, well-rounded steel, framed in wood.
The 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.
The principle of the compensating brake devised by J.
This form of brake was also invented independently by J.
In the second, or " braking off " method, the brake is automatically applied by a spring or weight, and is released either mechanically or, in the case of electric cranes, by the pull of a solenoid or magnet which is energized by the current passing through the motor.
In America, also, freight trains are fitted with an automatic continuous brake, whereas in the United Kingdom this appliance is required by law only in the case of passenger trains, and in fact is not fitted to goods and mineral trains except in a few isolated instances.
In an effective water-brake invented by W.
In this way the brake may be arranged to maintain a constant torque, notwithstanding variation of the speed.
To guard against this it is now customary to use some speed-checking appliance, independent of the engine-man, which reduces or entirely cuts off the steam supply when the cage arrives at a particular point near the surface, and applies the brake if the load is travelling too quickly.
Engines specially designed for testing are usually provided with a brake wheel having a trough-shaped rim.
A self-compensating brake of another kind, by Marcel Deprez, was described with Carpentier's in 1880 (Bulletin de la societe d'encouragement, Paris).
Is 116,772 foot-pounds, and a brake 5 ft.
In one of these a copper disk, called the brake disk, revolves, and in the other a copper armature disk.
The current to be measured passes transversely across the disk and causes it to revolve in the magnetic field; at the same time the copper brake, geared on the same shaft, revolves in the field and has local or eddy currents produced in it which retard its action.
Hence when a current is passed through the meter, the armature rotates and increases its speed until the driving force is balanced against the retarding force due to the eddy currents in the copper brake disk.
For the "Prony Brake" see Dynamometer.
A very convenient rule is to allow one brake horse-power of motor for every to foottons of work done at the hook; this is equivalent to an efficiency of 661%, and is well on the safe side.
In addition to the brakes on the lifting gear of cranes it is found necessary, especially in quickrunning electric cranes, to provide a brake on the subsidiary motions, and also devices to stop the motor at the end of the lift or travel, so as to prevent over-running.
On the same shaft with P is fixed a brake-wheel furnished with a powerful brake B, by the proper manipulation of which the speed of paying out is regulated, the pull on the cable being at the same time observed by means of D.
Had been laid, the cable snapped, owing to a mistake in the manipulation of the brake, and the ships returned to Plymouth with what remained.
To "heave the log," a man holds the log-reel over his head (at high speeds the man and portable reel are superseded by a fixed reel and a winch fitted with a brake), and the officer places the peg in the log-ship, which he then throws clear and to windward of the ship, allowing the line to run freely out.
The final settlement of a rule requiring brake-levers to be fitted on both sides of goods-wagons was, however, deferred, owing to objections raised by certain of the railway companies.
The horsepower available at the driving-axle, conveniently called the brake horse-power, is from 20 to 30% less than the indicated horse-power, and the ratio, B.H.P./I.H.P. =E, is called the mechanical efficiency of the steam engine.
The soundings are made by means of a special machine fitted with a brake so adjusted that the revolution of the drum is stopped automatically the instant the lead touches the bottom, and the depth can then be read directly from an indicator.
If the brake is not balanced, its moment about the axis must be included.
The latter is commonly referred to as the " brake horse-power."
A flexible steel band, lined with wood blocks, is gripped on the motor fly-wheel or pulley by a screw A, which, together with W, is adjusted to hold the brake steady.
Both these forces usually act at the same radius R, the distance from the axis to the centre line of the rope, in which case the torque T is (W-p)R, and consequently the brake horse-power is (W - p)RX21rN, When µ 33,000 changes the weight W rises or falls against the action of the spring balance until a stable condition of running is obtained.
A and B are fast and loose pulleys, and the brake band is placed partly over the one and partly over the other.
Other towns past which it flows between Munden and the sea are Karlshafen, Hoxter, Holzminden, Bodenwerder, Hameln, Rinteln,Vlotho, Minden, Stolzenau,Nienburg, Vegesack, Elsfleth, Brake, Geestemunde and Bremerhaven.
When the motor starts the brake is released; when it stops, or the current ceases, the brake goes on.
In the United Kingdom, as in Europe generally, the vehicles used on passenger trains include firstclass carriages, second-class carriages, third-class carriages, composite carriages containing compartments for two or more classes of passengers, dining or restaurant carriages, sleeping carriages, mail carriages or travelling post offices, luggage brake vans, horse-boxes and carriage-trucks.
In addition to the various works of Brewster already noticed, the following may be mentioned: - Notes and Introduction to Carlyle's translation of Legendre's Elements of Geometry (1824); Treatise on Optics (1831); Letters on Natural Magic, addressed to Sir Walter Scott (1831); The Martyrs of Science, or the Lives of Galileo, Tycho Brake, and Kepler (1841); More Worlds than One (1854).
The grades must not be too great for brake control nor for the hauling back of the empty cars.
A road maybe used as a self-acting or gravitating incline when the gradient is r in 30 or steeper, in which case the train is lowered by a rope passing over a pulley or brake drum at the upper end, the return empty train being attached to the opposite end of the rope and hauled up by the descending load.
The arrangements for this purpose vary, of course, with the amount of work to be done with one fixing of the machinery; where it is likely to be used for a considerable time, the drum and brake are solidly constructed, and the ropes of steel or iron wire carefully guided over friction rollers, placed at intervals between the rails to prevent them from chafing and wearing out on the ground.
When the load is being drawn out, the engine pulls directly on the main rope, coiling it on to its own drum, while the tail drum runs loose paying out its rope, a slight brake pressure being used to prevent its running out too fast.
The external forces holding the brake from turning are W, distant R from the axis, and the reaction, W 1 say, of the lever against the fixed pin P, distant R1 from the axis.
A weight is moved along the arm of one of the beams until it just keeps the brake steady midway between the stops which must be provided to hold it when the weight fails to do so.
The general theory of this kind of brake is as follows: - Let F be the whole frictional resistance, r the common radius of the rubbing surfaces, W the force which holds the brake from turning and whose line of action is at a perpendicular distance R from the axis of the shaft, N the revolutions of the shaft per minute, co its angular velocity in radians per second; then, assuming that the adjustments are made so that the engine runs steadily at a uniform speed, and that the brake is held still, clear of the stops and without oscillation, by W, the torque T exerted by the engine is equal to the frictional torque Fr acting at the brake surfaces, and this is measured by the statical moment of the weight W about the axis of revolution; that is T =Fr=WR...
Thus this kind of brake, though cheap to make, is, when 0 is large enough, an exceedingly accurate measuring instrument, readily applied and easily controlled.
Barrel cranes are usually fitted with band brakes, consisting of a brake rim with a friction band placed round it, the band being tightened as required.
The speed due to the excess of weight on the loaded side is controlled by a brake on the drum.
Brake, Germany >>
An excellent brake for very large cranes is Matthew's hydraulic brake, in which water is passed from end to end of cylinders fitted with reciprocating pistons, cooling jackets being provided.
The first curve frightened the hell out of him and he knew the brake pressure necessary to slow him from this speed could not be engaged all the way down the mountain without overheating the tiny pads to the point of ineffectiveness.
By a brake-wheel of this kind 18 in.
The first method is in general use for steam cranes; it allows for a far greater range of power in the brake, but is not automatic, as is the second.