# Horse-power Sentence Examples

If we could drive the engine so fast as to reduce C' to zero, the whole of the energy of the battery would be available, no heat being produced in the wires, but the horse-power of the engine would be indefinitely small.

It is practically important to consider the rate at which energy may be transformed into useful work, or the horse-power of the agent.

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.

The unit of power commonly used by engineers is the horse-power, and this unit corresponds to a rate of working of 550 foot-lb of work per second.

The indicated horse-power developed by a cylinder may always be ascertained from an indicator diagram and observations of the speed.

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.

Thus if the maximum horse-power which a locomotive can develop is woo, the tractive resistance R, at 60 m.

This is the horse-power, therefore, which must be developed in the cylinders to maintain the train in motion at a uniform speed of 40 m.

This must be exerted in addition to the horse-power calculated in the previous section, so that the total indicated horse-power which must be developed in the cylinders is now 354+223 =577.

Therefore the horse-power which must be developed in the cylinders to effect this change of speed is from (21) H.P.280X2240X0 113X59 = _237 55 0 X 32 The rate of working is negative when the train is retarded; for instance, if the train had changed its speed from 41 to 40 m.

AdvertisementAs the indicated horse-power of the engine increases, the weight of steam discharged increases, and the smoke-Lox vacuum is increased, thereby causing more air to flow through the furnace and increasing the rate of combustion.

The expression for the indicated horse-power may be written I.H.P. =pay/550 (27) where v is the average piston speed in feet per second.

Any modification of the design which will reduce the resistance to the flow of steam through the steam passages at high speeds will increase the piston speed for which the indicated horse-power is a maximum.

In 1888, at Nottingham, hay and straw presses for steam-power, horse-power and handpower were the subjects of competition.

In 1900, at York, the competitions were concerned with horse-power cultivators, self-moving steam diggers, milking machines and sheep-shearing machines (power and hand).

AdvertisementThe wet seasons that set in at the end of the 'seventies led to so much hindrance in the work on the land that the aid of steam was further called for, and it seemed probable that there would be a lessened demand for

**horse power**.A similar, but larger machine, requiring about horse-power to run it, will turn out 50 to 60 lb of Egyptian or 60 to 80 lb of Sea Island cleaned cotton per hour.

The engine, which is provided with reversing gear, is of 12 or 15 horse-power and motion is communicated through a belt to the band-wheel, which operates the walking-beam by means of a crank.

In many experiments, however, different inductions and frequencies are employed, and the hysteresis-loss is often expressed as ergs per cubic centimetre per cycle and sometimes as horse-power per ton.

Since t horse-power= 746 watts, and r ton = 2 240 lb, the factor for reducing horse-power per ton to watts per lb is 746/2240, or just 1/3.

AdvertisementMassimo to the suburb of Tombetta, furnishes 26 cubic metres of water per second, and generates 4000 horse-power.

The name has been applied generally to all kinds of instruments used in the measurement of a force, as for example electric dynamometers, but the term specially denotes apparatus used in connexion with the measurement of work, or in the measurement of the horse-power of engines and motors.

The latter is commonly referred to as the " brake horse-power."

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.

These measurements were utilized in combination with appropriate elastic coefficients of the material to find the horse-power transmitted from the engines along the shaft to the propeller.

AdvertisementIn this way the effective horse-power and also the mechanical efficiency of a number of large marine engines, each of several thousand horse-power, have been determined.

In the United States the Philadelphia mint was opened in 1792, but only manual or

**horse power**was used until 1836, when steam was introduced.The labour of rolling the metal by hand was done away with about 1760, by the firm of Tudor, Leader & Sherburn, who first employed horse-power, and for more than half a century the trade both in Sheffield and Birmingham continued to flourish.

The St Lawrence system, for instance, generates many thousand horse-power at Sault Ste Marie, Niagara and the Lachine rapids.

It has been calculated that the gas from a pair of old-fashioned blast-furnaces making i 600 tons of iron per week would in this way yield some 16,000 horse-power in excess of their own needs, and that all the available blast-furnace gas in the United States would develop about i,50o,000 horse-power, to develop which by raising steam would need about 20,000,000 tons of coal a year.

The large circular millstones of Roman age worked by horse-power are usually made from slices of granite columns.

The unit of power, called conventionally a horse-power, is 550 foot-pounds per second, or 33,000 foot-pounds per minute, or 1,980,000 foot-pounds per hour.

See also DYNAMOMETER for illustrations of the use of what are essentially friction-straps of different forms for the measurement of the brake horse-power of an engine or motor.

Horse-power is still extensively resorted to along the three canal systems. The first large steamers of the American type were built in 1872.

With too% currentefficiency and a potential difference of 0.3 volt between the electrodes, t lb of copper should require about o-154 electrical horse-power hours as the amount of energy to be expended in the tank for its production.

In practice the expenditure is somewhat greater than this; in large works the gross horse-power required for the refining itself and for power and lighting in the factory may not exceed 0.19 to 0.2 (or in smaller works 0.25) horse-power hours per pound of copper refined.

The device, frequently seen in farmyards, by which the power of a horse is utilized to drive threshing or other machinery, is sometimes described as a "horse-power," but this term usually denotes the unit in which the performance of steam and other engines is expressed, and which is defined as the rate at which work is done when 33,000 lb are raised one foot in one minute.

On the metric system it is reckoned as 4500 kilogram-metres a minute, and the French cheval-vapeur is thus equal to 32,549 foot-pounds a minute, or 0.9863 of an English horse-power, or 736 watts.

The "nominal horse-power" by which engines are sometimes rated is an arbitrary and obsolescent term of indefinite significance.

A statement of indicated horse-power supplies a measure force acting in the cylinder of an engine, but the power available for doing external work off the crank-shaft is less than this by the amount absorbed in driving the engine itself.

The useful residue, known as the "actual," "effective" or "brake" horse-power, can be directly measured by a dynamometer; it amounts to about 80% of the indicated horse-power for good condensing engines and about 85% for non-condensing engines, or perhaps a little more when the engines are of the largest sizes.

When turbines, as often happens in land practice, are directly coupled to electrical generators, their horse-power can be deduced from the electrical output.

The twist or surface-shear being proportional to the torque, the horse-power can be calculated if the modulus of rigidity of the steel employed is known or if the amount of twist corresponding to a given power has previously been ascertained by direct experiment on the shaft before it has been put in place.

Practical results with a large plant indicate an expenditure of 1.23 electrical horse-power hours per 100 oz.

From experiments made with this model, Penaud calculates that one horse-power would elevate and support 85 lb.

Each of them was independently governed, and furnished together 363 horse-power in actual effect, an amount which, considering that their total weight was only 600 lb, gave the extraordinary efficiency of over i horsepower for every 2 lb weight.

The steam engine weighed about 7 lb per horse-power, but the equilibrium of the apparatus 'was defective.

The engine was an eight-cylinder Antoinette petrol motor, developing 49 horse-power at 1100 revolutions a minute, and driving directly a single metal screw propeller.

Making about 1200 revolutions a minute, it developed about 24 horse-power, and was connected by chain gearing to two wooden propellers, 21metres in diameter and 31 metres apart, the speed of which was about 450 revolutions a minute.

The corresponding intensity at the sun's surface is 4.62 X Io 4 as great, or 6.79 X Io 4 kilowatts per square metre = 7.88 X Io 4 horse-power per square yard - enough to melt a thickness of 13.3 metres (=39.6 ft.) of ice, or to vaporize 1.81 metres (=5.92 ft.) of water per minute.

The practice of using actual

**horse power**to haul the trucks to the line died out with the introduction of the diesel engine.A good oil engine should not require to use more than a pint of refined petroleum per indicated horse-power working for one hour.

But when we come to R G Blaine he simply sidesteps the issue of time by introducing

**horse power**hour.If the train is running down a gradient this horse-power is the rate at which gravity is working on the train, so that with the data of the previous section, on the assumption that the train is running down a gradient of I in 300, the horse-power required to maintain the speed would be 354-223=131.

The average acceleration in feet per second is measured by the fraction Change of speed in feet per sec. 60.07-58.6 64 tons; and to obtain the horse-power the boiler will be one of the largest that can be built to the construction gauge.

The "indicated horse-power" of a reciprocating engine is given by Aspn/ 33,000, where A is the area of the piston in square inches, S the length of the stroke in feet, P the mean pressure on the piston in lb per sq.

The relation between the b.h.p. and the torque on the driving-axle is 55 o B.H.P. =Tu., (9) It is usual with steam locomotives to regard the resistance R as including the frictional resistances between the cylinders and the driving-axle, so that the rate at which energy is expended in moving the train is expressed either by the product RV, or by the value of the indicated horse-power, the relation between them being 55 0 I.H.P. =RV (Io) or in terms of the torque 55 0 I.H.P.X€=RVe=TW (II) The individual factors of the product RV may have any value consistent with equation (to) and with certain practical conditions, so that for a given value of the I.H.P. R must decrease if V increases.