See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

POWER TRANSMISSION  . The appliances connected with installations for the utilization of natural See also:

• SOURCES

sources of See also:

• ENERGY (from the Gr. ivipyela; iv, in, ipyov, work)

energy may be classified into three See also:

• GROUPS
• GROUPS, THEORY

groups: I . See also:

• PRIME, PRIMER AND PRIMING

Prime See also:

• MOVERS, FRANZ KARL (18o6–1856)

movers, by means of which the natural See also:

• FORM (Lat. forma)

form of energy is transformed into See also:

• MECHANICAL

mechanical energy . To this See also:

• GROUP

group belong all such appliances as See also:

• WATER

water turbines, See also:

• STEAM
• STEAM (0. Eng. steam, vapour, smoke, cf. Du. steam; the origin is unknown)

steam turbines, steam engines and boilers, See also:

• GAS

gas producers, gas engines, oil engines, &c . 2 . Machinery of any See also:

• KIND (O. E. ge-cynde, from the same root as is seen in " kin," supra)

kind which is driven by energy made available by the prime mover . To this group belong all See also:

• MACHINE
• MACHINE (through Fr. from Lat. form machina of Gr. µnxavil)

machine of energy to drive it . 3 . The appliances by means of which the energy made avail-able by the prime mover is transmitted to the machine designed to utilise it . The See also:

• TERM

term See also:

• POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power is used to denote the See also:

• RATE

rate at which energy is transmitted . The unit of power in See also:

• COMMON

common use is the See also:

• HORSE (a word common to Teutonic languages in such forms as hors, hros, ros; cf. the Ger. ross)

horse power, and one horse power means a rate of transmission of 550 See also:

• FOOT

foot-pounds per second . In many cases the prime mover is combined with the machine in such a way that the transmitting mechanism is not distinctly differentiated from either the prime mover or the machine, as in the See also:

• CASE
• CASE, JOHN (d. 1600)

case of the See also:

• LOCOMOTIVE

locomotive See also:

• ENGINE
• ENGINE (Lat. ingenium)

engine .

In other cases the energy made available by the prime mover is distributed to a number of See also:

• SEPARATE

separate See also:

• MACHINES

machines at a distance from the prime mover, as in the case of an engineer's workshop . In this case the transmitting mechanism by means of which the energy is distributed to the several machines has a distinct individuality . In other cases prime movers are located in places where the natural source of energy is abundant, namely, near waterfalls, or in the neighbourhood of See also:

• COAL

coal-See also:

• FIELDS, JAMES THOMAS (1817-1881)

fields, and the energy made available is transmitted in bulk to factories, &c., at relatively See also:

• GREAT

great distances . In this case the method and mechanism of See also:

• DISTRIBUTION (Lat. distribuere, to deal out)

distribution become of See also:

• PARAMOUNT (Anglo-Fr. paramont, up above, par el mont, up or on top of the mountain)

paramount importance, since the distance between the prime mover and the places where the energy is to be utilized by machines is only limited by the efficiency of the mechanism of distribution.' Prime movers are considered in the articles STEAM ENGINE; GAS ENGINE; OIL ENGINE, and See also:

• HYDRAULICS (Gr. iS&,p, water, and ai,Xos, a pipe)

HYDRAULICS, and machines in various See also:

• SPECIAL

special articles . The methods and mechanisms of distribution or transmission alone form the subjects of the See also:

• PRESENT

present See also:

• ARTICLE (from Lat. articulus, a joint)

article, and the different methods in See also:

• GENERAL
• GENERAL (Lat. generalis, of or relating to a genus, kind or class)

general use readily fall into four divisions: I . Mechanical . 3 . Pneumatic . 2 . See also:

• HYDRAULIC

Hydraulic . 4 . See also:

• ELECTRICAL
• ELECTRICAL (or ELECTROSTATIC) MACHINE

Electrical .

I.—MECHANICAL § 1 . Methods.—The mechanical transmission of power is effected in general by means of belts or See also:

• ROPES, JOHN CODMAN (1836–1899)

ropes, by shafts or by See also:

• WHEEL (0. Eng. hweol, hweohl, &c., cognate with Icel. hjol, Dan. hiul, the Indo-European root is seen in Sanskrit chakra, Gr. r in Aos, circle, whence " cycle ")
• WHEEL, BREAKING ON THE

wheel gearing and chains . Each individual method may be used separately or in See also:

• COMBINATION (Lat. combinare, to combine)

combination . The problems involved in the See also:

• DESIGN (Fr. desiin, drawing; Lat. designare, to mark out)

design and arrangement of the mechanisms for the mechanical distribution of power are conveniently approached by the See also:

• CONSIDERATION (from Lat. considerare, to look at closely, examine, generally taken to be from con-, and the base seen in sidus, sideris, a star, the word being supposed to be originally an astrological or astronomical term)

consideration of the way in which the mechanical energy made avail-able by an engine is distributed to the several machines in the factory . By a See also:

• BELT (a word common to Teutonic languages, the Old Ger. form being bale, from which the Lat. balteus probably derived)
• BELT, THOMAS (1832-1878)

belt on the See also:

• FLY (formed on the root of the supposed original Tent. fleugan, to fly)

fly-wheel of the prime mover the power is transmitted to the See also:

• LINE

line See also:

• SHAFT
• SHAFT (O. Eng., sceaft, from scafan, to shave; the word is common to Teutonic languages)

shaft, and pulleys suitably placed along the line shaft by means of other belts transmit power, first, to small countershafts carrying fast and loose pulleys and striking See also:

• GEAR (connected with " garb," properly elegance, fashion, especially of dress, and with " gar," to cause to do, only found in Scottish and northern dialects; the root of the word is seen in the Old Tent. garwjan, to make ready)

gear for starting or stopping each engine at will, and then to the See also:

• DRIVING (from " to drive," i.e. generally to propel, force along or in, a word common in various forms to the Teutonic languages)

driving pulleys of the several machines . (See also PULLEYS.) § 2 . Quantitative Estimation of the Power Transmitted.—In dealing with the See also:

• MATTER

matter quantitatively the engine See also:

• CRANK

crank-shaft may be taken as the starting point of the transmission, and the first See also:

• MOTION (Lat. motio, from movere, to move)
• MOTION, LAWS OF

motion-shaft of the machine as the end of the transmission so far as that particular machine is concerned . Let T be the mean See also:

• TORQUE, or TORO (Lat. torquis, torques, a twisted collar, torquere, to twist)

torque or turning effort which the engine exerts continuously on the crank shaft when it is making N revolutions per second . It is more convenient to See also:

• EXPRESS (through the French from the past participle of the Lat. exprimere, to press out, by transference used of representing objects in painting or sculpture, or of thoughts, &c. in words)

express the revolutions per second in terms of the angular velocity co, that is, in radians per second . The relation between these quantities is w=2rN . Then the,rate at which See also:

• WORK

work is done by the engine crank shaft is Ts) foot-pounds per second, See also:

• EQUIVALENT

equivalent to Tw/550 horse power . This is now distributed to the several machines in varying proportions .

Assuming for the See also:

• SAKE

sake of simplicity that the whole of the power is absorbed by one machine, let T, be the torque on the first motion-shaft of the machine, and let See also:

• EA(nar...), (p.s„,.,.)
• EA(psr...), (p, „...)• (pqr...)

ea be its angular velocity, then the rate at which the machine is absorbing energy is Tiwl foot-pounds per second . A certain quantity of energy is absorbed by the transmitting mechanism itself for the purpose of overcoming frictional and other resistances, otherwise the rate of absorption of energy by the machine would exactly equal the rate at which it was produced by the prime mover assuming steady conditions of working . Actually therefore Tiwl would be less than Tw, so that Tiwi = ~1~ w~ (I) § 4 . Example of Preliminary Design of a Belt.—The following example illustrates the use of the equations for the design of a belt in the See also:

• ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary way . Find the width of a belt to transmit 20 h.p. from the flywheel of an engine to a shaft which runs at 18o revolutions per miunte (equal to 18.84 radians per second), the See also:

• PULLEY

pulley on the shaft being 3 ft. See also:

• DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter . Assume the engine flywheel to be of such diameter and at such a distance from the driven pulley that the arc of contact is 120°, equal to 2.094 radians, and further assume that the coefficient of See also:

• FRICTION (from Lat. fricare, to rub)

friction is =0.3 . Then from See also:

• EQUATION (from Lat. aequatio, aequare, to equalize)

equation (5) t/u=e2.094X0.3=2.7180.6282; that is loget/u=o•6282, from which t/u=I.87, and u=t/1.87 . Using this in (3) we have 1(I-I/I.87) 1.5 X 18.84 = 550 X 20, from which t = 838 lb . Allowing a working strength of 300 lb per square See also:

• INCH (O. Eng. ynce from Lat. uncia, a twelfthpart; cf. " ounce," and see As)

inch, the See also:

• AREA

area required is 2.8 sq. in., so that if the belt is 4 in. thick its width would be 11.2 in., or if ss in. thick, 15 in. approximately . The effect of the force constraining the circular motion in diminishing the horse power transmitted may now be ascertained by calculating the horse power which a belt of the See also:

• SIZE

size found will actually transmit when the maximum tension t is 838 lb . A belt of the area found above would weigh about P4 lb. per foot . The velocity of the belt, v = wr =18.84 X1.5 =28.26 ft. per second .

The term Wv2/g therefore has the numerical value 34.7 . Hence equation (2) becomes (t—34.7)/(u—34.7) =1.87, from which, inserting the value 838 for t, n=464.5 lb . Using this value of u in equation (I) H.P . _ (838 — 464.5) X 18.84 X 1.5 550 =19.15 . where n is called the efficiency of the transmission . Considering now the general problem of a multiple machine transmission, if Tl, wl, T2, See also:

• W2(P — R1)

w2,T3, w3,.... are the several torques and angular velocities of the respective first motion shafts of the machines, (Tito( +T2o.,2 + T 3a.,3 + .. . .) =nTw (2) expresses the relations which must exist at any instant of steady motion . This is not quite a See also:

• COMPLETE

complete statement of the actual conditions because some of the provided energy is always in course of being stored and unstored from instant to instant as kinetic energy in the moving parts of the mechanism . Here, n is the over-all efficiency of the distributing mechanism . We now consider the separate parts of the transmitting mechanism . § 3 . Belts.—Let a pulley A (fig. i) drive a pulley B by means of a See also:

• LEATHER (a word which appears in all Teutonic languages; cf. Ger. Leder, Dutch leer or leder, Swed. leder, and in such Celtic forms as Welsh llader)
• LEATHER, ARTIFICIAL

leather belt, and let the direction of motion be as indicated by the arrows on the pulleys .

When the pulleys are revolving uniformly, A transmitting power to B, one See also:

• SIDE
• SIDE (mod. Eski Adalia)

side of the belt will be tight and the other 'side will be slack, but both sides will be in a See also:

• STATE
• STATE, GREAT OFFICERS OF

state of tension . Let t and u be the respective tensions on the tight and slack side; then the torque exerted by the belt on the pulley B is (t—u)r, where r is the See also:

• RADIUS

radius of the pulley in feet, and the rate at which the belt does work on the pulley is (t—u)rw foot-pounds per second . If the horse-power required to drive the machine be represented by h.p., then (t—u)rw=55o h.p., (3) assuming the efficiency of the transmission to be unity . This equation contains two unknown tensions, and before either can be found another See also:

• CONDITION (Lat. condicio, from condicere, to agree upon, arrange; not connected with conditio, from condere, conditum, to put together)

condition is necessary . This is supplied by the relation between the tensions, the arc of contact e, in radians (fig . 2), the coefficient of friction A between the belt and the pulley, the See also:

• MASS (O.E. maesse; Fr. messe; Ger. Messe; Ital. messa; from eccl. Lat. missa)
• MASS, IN

mass of the belt and the See also:

• SPEED, JOHN (1552–1629)

speed of the belt . Consider an See also:

• ELEMENT (Lat. elementum)

element of the belt (fig . 2) sub- tending an See also:

• ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle do at the centre of the pul- ley, and let t be the tension on one side of g"~~dO the element and (t+dt) the tension of the other side . The ten- See also:

• SION [Ger. Sitten]

sion tending to cause the element to slide bodily See also:

• ROUND (O. Fr. rond, Lat. rotundus, the Fr. is the source also of Du. rond; Ger., Swed., Dan. and Nor. rond)

round the sur- See also:

• FACE (from Lat. fades, derived either from facere, to make, or from a root fa-, meaning " appear "; cf. Gr. cbatvstv)

face of the pulley is dt . t+dt The normal pressure and the face of the pulley due to the tensions is t do, but this is diminished by the force necessary to constrain the element to move in the circular path determined by the curvature of the pulley . If W is the See also:

• WEIGHT

weight of the belt per foot, the constraining force required for this purpose is Wv2de/g, where v is the linear velocity of the belt in feet per second . Hence the frictional resistance of the element to sliding is (t—Wv2/g)cido, and this must be equal to the difference of tensions dt when the element is on the point of slipping, so that (1— Wv2/ g)side =cit .

The See also:

• SOLUTION (from Lat. solvere, to loosen, dissolve)

solution of this equation is t — Wv2/g (4) u—Wv-;g eµ , where t is now the maximum tension and u the minimum tension, and e is the See also:

• BASE

base of the Napierian See also:

• SYSTEM

system of logarithms, 2.718 . Equations (3) and (4) See also:

• SUPPLY (through Fr. from Lat. supplere, to fill up)

supply the condition from which the power transmitted by a given belt at a given speed can be found . For ordinary work the term involving v may be neglected, so that (4) becomes t/u =eµ9 . (5) Equations (3) and (5) are ordinarily used for the preliminary design of a belt to calculate t, the maximum tension in the belt necessary to transmit a stated horse power at a stated speed, and then the See also:

• CROSS

cross See also:

• SECTION
• SECTION (Lat. sectio, cutting, secare, to cut)

section is proportioned so that the stress per square inch shall not exceed a certain safe limit determined from practice . To facilitate the calculations in connexion with equation O, tables are constructed giving the ratio t/u for various values of si and o . (See W . C . Unwin, Machine Design, 12th ed., p . 377.) The ratio should be calculated for the smaller pulley . If the belt is arranged as in fig. i, that is, with the slack side uppermost, the drop of the belt tends to increase 0 and hence the ratio t/u for both pulleys . § 5 . Belt Velocity for Maximum Horse Power.—If the weight of a belt per foot is given, the speed at which the maximum horse power is transmitted for an assigned value of the maximum tension t can be calculated from equations (3) and (4) as follows: Let t be the given maximum tension with which a belt weighing W lb per foot may be worked .

Then solving equation (4) for u, subtracting t from each side, and changing the signs all through: l—u=(t—Wv2/g) (1—e ee) . And the rate of working U, in foot-pounds per second, is U=(t—u)v=(tv—Wv3/g)(1—e 0)• Differentiating U with regard to v, equating to zero, and solving for v, we have v = ~l (tg/3W) . Utilizing the data of the previous example to illustrate this matter, 1=838 lb per square inch, W =I.4 lb per foot, and consequently, from the above expression, v=8o ft. per second approximately . A See also:

• LOWER

lower speed than this should be adopted, however, because the above investigation does not include the loss incurred by the continual bending of the belt round the circumference of the pulley . The loss from this cause increases with the velocity of the belt, and operates to make the velocity for maximum horse power considerably lower than that given above . § 6 . Flexibility.—W See also:

• HEN

hen a belt or rope is working power is absorbed in its continual bending round the pulleys, the amount depending upon the flexibility of the belt and the speed . If C is the couple required to See also:

• BEND

bend the belt to the radius of the pulley, the rate at which work is done is Cw foot-pounds per second . The value of C for a given belt varies approximately inversely as the radius of the pulley, so that the loss of power from this cause will vary inversely as the radius of the pulley and directly as the speed of revolution . Hence thin flexible belts are to be preferred to thick stiff ones . Besides the loss of power in transmission due to this cause, the bending causes a stress in the belt which is to be added to the See also:

• DIRECT

direct stress due to the tensions in the belt in See also:

• ORDER
• ORDER (through Fr. ordre, for earlier ordene, from Lat. ordo, ordinis, rank, service, arrangement; the ultimate source is generally taken to be the root seen in Lat. oriri, rise, arise, begin; cf. " origin ")
• ORDER, HOLY

order to find the maximum stress . In ordinary leather belts the bending stress is usually negligible; in ropes, how-ever, especially See also:

• WIRE (A.S. wir, a wire; cf. Swed. vire, to twist, M.H.G. wiere, a gold ornament, Lat. viriae, armlets, ultimately from the root wi, to twist, bind)

wire rope, it assumes paramount importance, since it tends to overstrain the outermost strands and if these give way the See also:

• LIFE

life of the rope is soon determined .

§ 7 . Rope Driving.—About 1856 See also:

• JAMES
• JAMES (Gr. 'IlrKw,l3or, the Heb. Ya`akob or Jacob)
• JAMES (JAMES FRANCIS EDWARD STUART) (1688-1766)
• JAMES, 2ND EARL OF DOUGLAS AND MAR(c. 1358–1388)
• JAMES, DAVID (1839-1893)
• JAMES, EPISTLE OF
• JAMES, GEORGE PAYNE RAINSFOP
• JAMES, HENRY (1843— )
• JAMES, JOHN ANGELL (1785-1859)
• JAMES, THOMAS (c. 1573–1629)
• JAMES, WILLIAM (1842–1910)
• JAMES, WILLIAM (d. 1827)

James See also:

• COMBE, ANDREW (1797-1847)
• COMBE, GEORGE (1788-1858)
• COMBE, or COOMB
• COMBE, WILLIAM (1741–1823)

Combe, of See also:

• BELFAST

Belfast, introduced the practice of transmitting power by means of ropes See also:

• RUNNING

running in grooves turned circumferentially in the rim of (From Abram Combe, Proc . Inst . Mech . Eng.) the pulley (fig . 3) . The ropes may be led off in groups to the different floors of the factory to pulleys keyed to the distributing shafting . A groove was adopted having an angle of about 45°, II u and this is the angle now used in the practice of Messrs Combe, See also:

• BARBOUR, JOHN (? 1316-1395)

Barbour and Combe, of Belfast . A section of the rim of a rope driving wheel showing the shape of the groove for a rope 11 in. diameter is shown in fig . 4, and a rope driving pulley designed for six I4in . ropes is shown in fig . 5 .

A rope is less flex- ible than a belt, and therefore care must be taken not to arrange rope drives with pul- See also:

• LEYS, HENDRIK, BARON (1815-1869)

leys having too small a diameter relatively to the diameter of the rope . The principles of §§ 3, 4, 5 and 6, apply equally to ropes, but with the See also:

• PRACTICAL

practical modification that the working stress in the rope is a much smaller fraction of the ultimate strength than in the case of belting and the ratio of the tensions is much greater . The following table, based upon the experience of Messrs Combe, presents the practical possibilities in a convenient form: t Smallest diameter of H.P. per Rope for Diameter Pulley, which should smallest Pulley at too of Rope. be used with the revs. per See also:

• MINUTE
• MINUTE (Lat. minutes, small; minuere, to make less)

minute . Rope . I 10 . I 28 14 8 21 16 42 66 The speed originally adopted for the rope was 55 ft. per second . This speed has been exceeded, but, as indicated above, for any particular case there is one speed at which the maximum horse power is transmitted, and this speed is chosen with due regard to the effect of centrifugal tension and the loss due to the continual bending of the rope round the pulley . Instead of using one rope for each groove, a single continuous rope may be used, driving from one common pulley several shafts at different speeds . For further See also:

• INFORMATION (from Lat. informare, to give shape or form to, to represent, describe)

information see Abram Combe, Proc . Inst . Mech . Eng .

(See also:

• JULY

July 1896) . Experiments to compare the efficiencies of rope and belt driving were carried out at See also:

• LILLE

Lille in 1894 by the Societe Industrielle du See also:

• NORD

Nord de la See also:

• FRANCE
• FRANCE, ANATOLE (1844– )

France, for an See also:

• ACCOUNT
• ACCOUNT (through O. Fr. acont, Late Lat. comptum, cornputare, to calculate)

account of which see D . S . Capper, Proc . Inst . Mech . Eng . (See also:

• OCTOBER

October 1896) . See also:

• COTTON
• COTTON (Fr. coton; from Arab. qutun)
• COTTON, CHARLES (163o–1687)
• COTTON, GEORGE EDWARD LYNCH (1813–1866)
• COTTON, JOHN (1585–1652)
• COTTON, SIR ROBERT BRUCE

Cotton ropes are used extensively for transmitting power in factories, and though more expensive than See also:

• MANILA

Manila ropes, are more durable when worked under suitable conditions . § 8 . Shafts.—When a shaft transmits power from a prime mover to a machine, every section of it sustains a turning couple 6= 11,500,606 x 3,14 x256 = 0'057 radians, and this is equivalent to 3'3°• In the case of hollow round shafts where D is the See also:

• EXTERNAL

external diameter and d the See also:

• INTERNAL

internal diameter equation (7) becomes T=irf(D4-d')/16D, (9) and equation (8) becomes T =COlr(D4-d')/32L . (1o) The See also:

• ASSUMPTION, FEAST OF

assumption tacitly made hitherto that the torque T remains See also:

• CONSTANT, BENJAMIN (1845-1902)

constant is rarely true in practice; it usually varies from instant to instant, often in a periodic manner, and an appropriate value of f must be taken to suit any particular case .

Again it rarely happens that a shaft sustains a torque only . There is usually a bending moment associated with it . For a discussion of the proper values of f, to suit cases where the stress is variable, and the way a bending moment of known amount may be combined with a known torque, see STRENGTH OF MATERIALS . It is sufficient to state here that if M is the bending moment in inch-pounds, and T the torque in inch-pounds, the magnitude of the greatest direct stress in the shaft due to the effect of the torque and twisting moment acting together is the same as would be produced by the application of a torque of M-~ J (T2+M2) inch-pounds . (II) It will be readily understood that in designing a shaft for the distribution of power to a factory where power is taken off at different places along the shaft, the diameter of the shaft near the engine must be proportioned to transmit the See also:

• TOTAL

total power transmitted whilst the parts of the shaft more remote from the engine are made smaller, since the power transmitted there is smaller . § 9 . Gearing See also:

• PITCH
• PITCH, MUSICAL

Pitch Chains.—Gearing is used to transmit power from one shaft to another . The shafts may be parallel; or inclined to one another, so that if produced they would meet in a point; or inclined to one another so that if produced they would not meet in a point . In the first case the gear wheels are called See also:

• SPUR (A.S. spura, spora, related to spornan, spurnan, to kick, spurn; cf. M.H.G. sporn, mod. Ger. Sporn)

spur wheels, sometimes See also:

• COG

cog wheels; in the second case See also:

• BEVEL (from an O. Fr. word, cf. mod. biveau, a joiner's instrument)

bevel wheels, or, if the angle between the shafts is 9o°, See also:

• MITRE (Lat. mitra, from Gr. j4rpa, a band, head-band, head-dress)

mitre wheels; and in the third case they are called skew bevels . In all cases the See also:

• TEETH (O.E. Eel); plural of tooth, O.E. top)

teeth should be so shaped that the velocity ratio between the shafts remains or torque T, and if co is the angular velocity of rotation in radians per second, the rate of transmission is T. foot-pounds per second, and the relation between the horse power, torque and angular velocity is Tm=550 H.P . (6) The problem involved in the design of a shaft is so to proportion the size that the stress produced by the torque shall not exceed a certain limit, or that the relative angular displacement of two sections at right angles to the See also:

• AXIS (Lat. for " axle ")

axis of the shaft at a given distance apart shall not exceed a certain angle, the particular features of the problem determining which condition shall operate in fixing the size . At a section of a solid round shaft where the diameter is D inches, the torque T inch-pounds, and the maximum shearing stress f pounds per square inch, the relation between the quantities is given by T=fD3.f/t6, (7) and the relation between the torque T, the diameter D, the relative angular displacement 0 of two sections L inches apart by T = C87rD4/32L, (8) where C is the modulus of rigidity for the material of the shaft .

Observe that 0 is here measured in radians . The ordinary problems of shaft transmission by solid round shafts subject to a See also:

• UNIFORM

uniform torque only can be solved by means of these equations . Calculate the horse power which a shaft 4 in. diameter can transmit, revolving 120 times per minute (12.56 radians per second), when the maximum shearing stress f is limited to 11,000 lb per square inch . From equation (7) the maximum torque which may be applied to the shaft is T =138,400 inch-pounds . From (6) H.P . =138,400 X 12'56 =264 . The example may be continued to 12 X 550 find how much the shaft will twist in a length of Io ft . Substituting the value of the torque in inch-pounds in equation (8), and taking 11,500,000 for the value of C, 138,400 X120 X32 constant, although in very rare cases gearing is designed to work with a variable velocity ratio as See also:

• PART

part of some special machines . For the principles governing the shape of the teeth to fulfil the condition that the velocity ratio between the wheels shall be constant, see See also:

• MECHANICS

MECHANICS, § Applied . The size of the teeth is determined by the torque the gearing is required to transmit . Pitch chains are closely allied to gearing; a See also:

• FAMILIAR (through the Fr. familier, from Lat. familiaris, of or belonging to the familia, family)

familiar example is in the driving See also:

• CHAIN (through the O. Fr. citable, chcene, &c., from Lat. catena)

chain of a See also:

• BICYCLE (from prefix bi = twice, and Gr. KuKXOr, a circle, wheel)

bicycle . Pitch chains are used to a limited extent as a substitute for belts, and the teeth of the chains and the teeth of the wheels with which they work are shaped on the same principles as those governing the design of the teeth of wheels .

If a pair of wheels is required to transmit a certain maximum horse power, the angular velocity of the shaft being w, the pressure P which the teeth must be designed to sustain at the pitch circle is 550 H.P./wR, where R is the radius of the pitch circle of the wheel, whose angular velocity is w . § io . Velocity Ratio.—In the case of transmission either by belts, ropes, shafts or gearing, the operating principle is that the rate of working is constant, assuming that the efficiency of the transmission is upity, and that the product Tw is therefore constant, whether the shafts are connected by ropes or gearing . Considering therefore two shafts, T1 w1=T2w2; that is w;/w2=T2/T1; i.e. the angular velocity ratio is inversely as the torque ratio . Hence the higher the speed at which a shaft runs, the smaller the torque for the transmission of a given horse power, and the smaller the tension on the belts or ropes for the transmission of a given horse power . § 11 . See also:

• LONG, GEORGE (1800-1879)
• LONG, JOHN DAVIS (1838– )

Long Distance Transmission of Power.—C . F . Hirn originated the transmission of power by means of wire ropes at See also:

• COLMAR, or KOLMAR

Colmar in See also:

• ALSACE (Ger. Elsass)

Alsace in 185o . Such a telodynamic transmission consists of a See also:

• SERIES (a Latin word from serere, to join)

series of wire ropes running on wheels or pulleys supported on piers at spans varying from 300 to 500 ft. between the prime mover and the See also:

• PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place where the power is utilized . The slack of the ropes is supported in some cases on See also:

• GUIDE (in Mid. Eng. gyde, from the Fr. guide; the earlier French form was guie, English " guy," the d was due to the Italian form guida; the ultimate origin is probably Teutonic, the word being connected with the base seen in O. Eng. witan, to know)

guide pulleys distributed between the See also:

• MAIN (from the Aryan root which appears in " may " and " might," and Lat. magnus, great)
• MAIN (Lat. Moenus)

main piers . In this way 300 h.p. was transmitted over a distance of 6500 ft. at See also:

• FREIBERG, or FREYBERG

Freiberg by means of a series of wire ropes running at 62 ft. per second on pulleys 177 in. diameter .

The individual ropes of the series, each transmitting 300 h.p., were each 1.o8 in. diameter and contained Io strands of 9 wires per strand, the wires being each 0.072 in. diameter . Similar installations existed at See also:

• SCHAFFHAUSEN
• SCHAFFHAUSEN (Fr. Schaffhouse)

Schaffhausen, Oberursal, See also:

• BELLEGARDE
• BELLEGARDE, HEINRICH JOSEPH JOHANNES, COUNT VON (1756-1845)

Bellegarde, See also:

• TORTONA (anc. Dertona)

Tortona and See also:

• ZURICH
• ZURICH (Fr. Zurich; Ital. Zurigo)

Zurich . For particulars of these transmissions with full details see W . C . Unwin's See also:

• HOWARD (FAMILY)
• HOWARD, CATHERINE (d. 1542)
• HOWARD, JOHN (1726-1790)
• HOWARD, LORD WILLIAM (1563–1640)
• HOWARD, OLIVER OTIS (1830-19o9)
• HOWARD, SIR ROBERT (1626–1698)

Howard Lectures on the " Development and Transmission of Power from Central Stations " (Journ . See also:

• SOC

Soc . Arts, 1893, published in See also:

• BOOK

book form 1894) . The system of telodynamic transmission would no doubt have See also:

• DEVELOPED

developed to a much greater extent than it has done but for the See also:

• ADVENT (Lat. Adventus, sc. Redemptoris, " the coming of the Saviour ")

advent of electrical transmission, which made practicable the transmission of power to distances utterly beyond the possibilities of any mechanical system . See W . J . M . See also:

• RANKINE, WILLIAM JOHN MACQUORN (182o-1872)

Rankine, See also:

• TREATISE

Treatise on Machinery and Millwork ; and W .

C . Unwin, Elements of Machine Design; and for telodynamic transmission see F . Reuleaux, See also:

• DIE
• DIE (Fr. de, from Lat. datum, given)

Die Konstrukteur . (W . E . D.) II.—HYDRAULIC The first proposal for a general transmission of hydraulic power was made by See also:

• BRAMAH, JOSEPH (1748-1814)

Bramah in 1802 . In 1846 See also:

• LORD
• LORD (O. Eng. hldford, i.e. hldfweard, the warder or keeper of bread, hlIf, loaf; the word is not represented in any other Teutonic language)
• LORD, JOHN (1810-1894)

Lord See also:

• ARMSTRONG, ARCHIBALD (d. 1672)
• ARMSTRONG, JOHN (1709-1779)
• ARMSTRONG, JOHN (1758—1843)
• ARMSTRONG, SAMUEL CHAPMAN (1839—1893)
• ARMSTRONG, WILLIAM GEORGE ARMSTRONG, BARON (1810—1900)

Armstrong's hydraulic See also:

• CRANE (in Dutch, Kraan; O. Ger. Kraen; cognate, as also the Lat. grus, and consequently the Fr. grue and Span. grulla, with the Gr. dpavos)
• CRANE, STEPHEN (1870-1900)
• CRANE, WALTER (1845– )
• CRANE, WILLIAM HENRY (1845– )

crane was erected at See also:

• NEWCASTLE
• NEWCASTLE, DUKES OF

Newcastle, and was worked from the See also:

• TOWN

town water mains, but the pressure in such mains was too See also:

• LOW, SETH (1850- )
• LOW, WILL HICOK (1853- )

low and uncertain to secure satisfactory results . The invention of the See also:

• ACCUMULATOR

accumulator in 1850 enabled much higher pressures to be used; since then 700 lb per square inch has been adopted in most private hydraulic power transmission See also:

• PLANTS

plants . An See also:

• ATTEMPT (Lat. adtemptare, attentare, to try)

attempt to give a public supply of hydraulic power was made in 1859, when a See also:

• COMPANY

company was formed for laying mains in See also:

• LONDON

London along the See also:

• RIVER

river See also:

• THAMES

Thames between the See also:

• TOWER (Lat. turris; Fr. tour, clocker; Ital. torre; Ger. Thurm)

Tower and Blackfriars, the engineer being See also:

• SIR

Sir See also:

• GEORGE
• GEORGE, 8TH MARQUESS OF TWEEDDALE (1787-1876)
• GEORGE, HENRY (1839—1897)
• GEORGE, LAKE
• GEORGE, SAINT (d. 303)

George ,See also:

• BRUCE
• BRUCE, ALEXANDER BALMAIN (1831-1899)
• BRUCE, JAMES (1930-1794)
• BRUCE, MICHAEL (1746-1767)

Bruce; but though an See also:

• ACT (Lat. actus, actum)

act of See also:

• PARLIAMENT (Anglo-Lat. parliamentum, Fr. parlement, from parler, to speak)

parliament was obtained, the See also:

• WORKS

works were not carried out . The first public hydraulic supply station was established at See also:

• HULL
• HULL (in O.Eng. hulu, from helan, to cover, cf. Ger. Hiille, covering)
• HULL (officially KINGSTON-UPON-HULL)
• HULL, ISAAC (1775-1843)

Hull in 1877 . In 1883 the General Hydraulic Power Works, Messrs Ellington and Woodall being the See also:

• ENGINEERS, MILITARY

engineers, were started in London, and they now form the largest system of hydraulic power transmission in existence . Works of a similar See also:

• CHARACTER (Gr. xapareri7p, from xap&crew, to scratch)

character have since been established in several other towns .

The general features ofhydraulic power transmissions are: (I) a central station where the hydraulic pressure is created, usually by means of steam pumping engines; (2) a system of distribution mains; (3) machines for utilizing the pressure . In cases of public supplies there is the further important matter of See also:

• REGISTRATION

registration . When dealing with any practical problem of hydraulic power transmission it is of the first importance to determine the maxi-mum demand for power, its duration and frequency . If the duration of the maximum demand is limited and the frequency restricted—for instance, when a See also:

• SWING, DAVID (1830-1894)

swing See also:

• BRIDGE

bridge has to be opened and closed only a few times in the course of a See also:

• DAY (O. Eng. dreg, Ger. Tag; according to the New English Dictionary, " in no way related to the Lat. dies")
• DAY, JOHN (1574-1640?)
• DAY, THOMAS (1748-1789)

day—a small pumping plant and a large accumulator will be desirable . If the maximum demand is more or less continuous, as when hydraulic pressure is used for working a See also:

• PUMP

pump in a mine or a hydraulic engine in a work-See also:

• SHOP

shop, the central station pumping engine must be capable of supplying the maximum demand without the aid of an accumulator, which may or may not, according to circumstances, be provided to serve as a regulator . A hydraulic accumulator (fig . 1) ordinarily consists of a hydraulic See also:

• CYLINDER (Gr. KvAwSpos, from KvXivaety, to roll)

cylinder . and See also:

• RAM
• RAM, PIERRE FRANCOIS XAVIER DE (18o4-1865)

ram, the ram being loaded with sufficient weight to give the pressure required in the hydraulic mains . If a pressure of 700 lb per square inch is wanted, the weight of the ram and its load, neglecting friction, must be 700 lb for each square inch of its area, and if the cylinder is full, i.e. the ram elevated to its full extent, the accumulator is a See also:

• RESERVOIR

reservoir of power, exactly as if it were a tank at the same cubical extent placed at an See also:

• ELEVATION

elevation of about 1600 ft. above the mains and connected with them . The See also:

• FUNCTION

function of accumulators in hydraulic power distribution is frequently misunderstood, and it has been urged that as in practice the size of the reservoirs of power that can be obtained by their use is small, they are of little value . An accumulator having a ram 20 in. diameter by 20 ft. stroke loaded to 700 lb is – Central Station . a fairly large one, but it contains only 439,740 foot-pounds of available energy .

If the accumulator ram descended in one minute the horse power developed during that See also:

• TIME (0. Eng. Lima, cf. Icel. timi, Swed. timme, hour, Dan. time; from the root also seen in " tide," properly the time of between the flow and ebb of the sea, cf. O. Eng. getidan, to happen, " even-tide," &c.; it is not directly related to Lat. tempus)
• TIME, MEASUREMENT OF
• TIME, STANDARD

time would be 13.3, and until again pumped up its function would cease . Is so small a reservoir See also:

• WORTH
• WORTH, CHARLES FREDERICK (1825-1895)

worth much ? The correct See also:

• ANSWER (derived from and, against, and the same root as swear)

answer to this question depends upon the surrounding circumstances . In the case of any general system of hydraulic power transmission it is certain that there will be very large and frequent See also:

• VARIATIONS
• VARIATIONS, CALCULUS
• VARIATIONS, CALCULUS OF

variations in the combined demand for power, the periods of approximate maximum rarely exceeding in the aggregate 2 or 3 See also:

• HOURS, CANONICAL

hours a day (see fig . 2) . Where the area of supply is very extensive there are further subsidiary variations in small sections of the area . The main features of the combined load curves are fairly constant, but the See also:

• LOCAL

local peaks are very erratic . Such conditions are favourable to the extensive use of accumulators . When comparing the See also:

• ECONOMY

economy of hydraulic machinery which works intermittently, such as See also:

• CRANES (so called from the resemblance to the long neck of the bird, cf. Gr. 'y pavor, Fr. grue)

cranes and hoists, with other systems the effect of the hydraulic accumulator in reducing the maximum horse power required is often neglected . In See also:

• CON

con-sequence the comparison is vitiated, because the minimum cost of running a central station depends to a great extent upon the .Nssa ,NN . o~YN maximum demand, even though the maximum may be required only during a few minutes of the day . In the hydraulic system accumulators at the central stations perform the two distinct functions of reducing the maximum load on the pumps which supply the demand, and regulating automatically the speed of the pumps as the demand varies from minute to minute .

In any large system where a number of pumping See also:

• UNITS, DIMENSIONS OF
• UNITS, PHYSICAL

units are required they also allow a sufficient See also:

• INTERVAL

interval of time to start any addi- tional units . Accumulators connected to the mains at a con- siderable distance from the central station reduce the variations of pressure, and the size of mains required for a given supply of power, and therefore have a most important See also:

• INFLUENCE (Late Lat. influentia, from influere, to flow in)

influence on the economy of distribution . The mechanical efficiency of hydraulic accumulators is very high, being from 95% to 98%, and they are practically indestructible . When designing central stations the aim should be to employ pumping engines of such capacity that they can be worked as nearly as possible continuously at about their maximum output; the same consideration should, in the main, determine the size of the pumping units in a station where more than a single unit is employed . With a number of units, each can be worked, when in use, at or near the most economical speed . Moreover, reserve plant is necessary if the supply of power is to be constant, and where the units are many the actual reserve required is less than where the units are few . An effect of the multiplication of power units is to increase the See also:

• CAPITAL (i.e. capital stock or fund)
• CAPITAL (Lat. caput, head)

capital outlay; indeed, it may be stated quite generally that economy in working and See also:

• MAINTENANCE (Fr. maintenance, from maintenir, to maintain, support, Lat. manu tenere, to hold in the hand)

maintenance cannot be obtained without a larger capital outlay than would be required for a simpler and less economical plant . A high degree of economy estimated on See also:

• FINANCIAL

financial data—the ultimate base on which these practical questions See also:

• REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest–can only be obtained in large installations where the averaging effect of the combination of a large number of comparatively small intermittent demands for power is greatest . The term load-See also:

• FACTOR (from Lat. facere, to make or do)

factor, since it was first coined by See also:

• COLONEL (derived either from Lat. column, Fr. colonne, column, or Lat. corona, a crown)

Colonel R . E . See also:

• CROMPTON
• CROMPTON, SAMUEL (1753-1827)

Crompton in 1891, has come into common use as an expression of the relation between the See also:

• AVERAGE

average and the maximum output from any central source of supply . No See also:

• ARGUMENT

argument is required to show that a given central station plant working continuously at its maximum speed day and See also:

• NIGHT

night all the See also:

• YEAR

year round, say for 876o hours in a year, should produce the power more cheaply per unit, not only as to the actual running cost, but also as to the capital or See also:

• INTEREST

interest charges, than the same plant running on the average at the same speed for, say, one-third the time, or 2920 hours .

In this case the load-factor 2920/8760= .333, or 33.370% . The saving on the whole See also:

• EXPENDITURE

expenditure per unit is not in direct proportion to an increase in the load-factor, and its effect on the various items of expenditure is extremely variable . The influence is greatest on the capital charges, and it has no influence at all, or may even have a detrimental effect, on some items; for instance, the cost of See also:

• REPAIRS (from Lat. reparare, to make ready again)

repairs per unit of output may be increased by a high load-factor . Its effect on the coal See also:

• CONSUMPTION (Lat. consumere)

consumption depends very much on the kind and capacity of the boilers in use; on whether the engines are condensing or non-condensing; on the hours of work of the engine See also:

• STAFF (O. Eng. staef, cf. Du. staf, Ger. Stab, &c.; Icel. stafr meant also a written letter, and O. Eng. stafas, the letters of the alphabet; " stave," one of the thin pieces of wood of which a cask is made, is a doublet)

staff, &c . The economic value of the load-factor is of great importance in every See also:

• INSTALLATION

installation, but its influence on the cost of supply varies at each central station, and must be separately determined . There is a load-factor See also:

• PECULIAR

peculiar to each use for which the power is supplied, and the whole load-factor can only be improved by the combination of different classes of demands, which differ in regard to the time of day or See also:

• SEASON (0. Fr. seson, seison, mod. saison, Lat. satio, sowing time, the spring, from serere, to sow; in Late Lat. the word is found with its present meaning, the spring being considered as particularly the season of the year)

season at which they attain their maximum . It is in this respect that the great economy of a public distribution of power is most apparent„ though there is also, of course, a direct economy due simply to the presumably large size of the central stations of a public supply . Demands for power of every kind have unfortunately a tendency to arise at the same time, so that in the See also:

• ABSENCE (Lat. absentia)

absence of storage of power there seems no prospect of the load-factors for general, supply of power in towns exceeding, in the most favourable conditions, 40% . The load-factor of most public hydraulic power supplies is considerably under 3o% . It is questionable, however, whether a very high load-factor conduces to economy of working expenses as a whole in any general supply of energy . The more continuous the supply during the twenty-four hours of the day the greater is the difficulty of executing repairs, and the greater the amount of the reserve plant required . In all central station work where fluctuating loads have to be dealt with it is most important that there should be ample See also:

• BOILER

boiler power .

In a comprehensive system of power supply demand arises in a very sudden and erratic manner, and to meet this by forcing the boilers involves greater See also:

• WASTE (O. Fr. wast, guast, gast, gaste; Lat. vastus, vast, desolate)

waste of coal than keeping steam up in sufficient reserve boilers . For this purpose boilers with large water capacity, such as the See also:

• LANCASHIRE

Lancashire, are preferable to the tubular type, if sufficient space is available . Superheated steam and also thermal storage are advantageous . Feed water heaters or economizers should always be used, all steam and feed pipes should be carefully protected from See also:

• RADIATION, THEORY OF

radiation, and the See also:

• PIPE

pipe flanges should be covered; in See also:

• SHORT, FRANCIS JOB (1857– )

short, to secure See also:

• GOOD, JOHN MASON (1764-1827)

good results in coal consumption every care must be taken to minimise the stand-by losses which are such serious items in central station economy when the load-factor is low . Though hydraulic power has the peculiar See also:

• ADVANTAGE

advantage, as regards coal consumption, that it is the speed of the engines which varies with an intermittent demand, nevertheless at the London stations it has been found that during a year's working only from 6o to 75% of the coal efficiency of trial runs of the engines can be obtained—i.e. at least 25 % of the coal is wasted through the stand-by losses and through the pumping engines having to run at less than full power . !N 3® Floneq.l.ep m ^ 0 HYDRAULIC] To determine the See also:

• SCALE
• SCALE (1) A

scale on which a central station plant should be designed is frequently a difficult matter . The rate of growth of the expected demand for the power is an important factor, but it has been clearly established that the reduction of working expenses resulting from the increase of size of an undertaking proceeds in a diminishing ratio . Increase in output is in fact sometimes accompanied by more than a proportionate increase of expenses . During See also:

• RECENT

recent years there have been causes at work which have raised considerably the See also:

• PRICE
• PRICE, BARTHOLOMEW (1818–1898)
• PRICE, BONAMY (1807-1888)
• PRICE, RICHARD (1723-1791)

price of labour, See also:

• FUEL (O. Fr. feuaile, popular Lat. focalia, from focus, hearth, fire)

fuel, other items of expense, and the See also:

• LAW
• LAW (0. Eng. lagu, M. Eng. lawe; from an old Teutonic root lag, " lie," what lies fixed or evenly; cf. Lat. lex, Fr. loi)
• LAW, JOHN (1671—1729)
• LAW, WILLIAM (1686-1761)

law of the " diminishing ratio " has been masked On the See also:

• DIAGRAM

diagram (fig . 3) of the See also:

• COSTS

costs of the London undertaking and the amount of power supplied, have been plotted points marking the total expenses of each year in relation to the output of power . These points for the years 1884-1899, and for output of from 50 to 700 million gallons followed approximately a straight line . Since 1899, however, though the output has increased from 708 millions to 1040 million gallons, the costs per unit of output have been always considerably above the preceding periods .

The details of the London supply given in tablet partly explain this by the relatively high price of fuel, but an equally important factor has been the rise in the local rates, which in the See also:

• PERIOD
• PERIOD (Gr. irepioSos, a going or way round, circuit, aepi, round, and &Sis, way, road)

period 1899–1909 have risen from 2d. up to 3d. per moo gallons . If the cost of fuel, rates and See also:

• WAGES (the plural of " wage," from Late Lat. wadium, a pledge, O. Fr. wagier, gagier)

wages had remained constant the plotting of expenses in relation to output would have been approximately along the See also:

• EXTENSION (Lat. ex, out ; tendere, to stretch)

extension .of the line AB . This line cuts the See also:

• VERTICAL (from Lat. vertex, highest point)

vertical axis at A above the origin 0, and the line OA indicates the minimum amount of the expenses, and by implication the initial size of the first central station erected in London . The See also:

• CURVE (Lat. curvus, bent)

curve in this diagram gives the cost per Iwo gallons . Whether it is more economical to have several smaller stations in any particular system of power transmission, or a single centre of supply, is mainly governed by the cost of the mains and the facilities for laying them in the area served . No general See also:

• RULE

rule can, however, be formulated, for it is a question of See also:

• BALANCE (derived through the Fr. from the Late Lat. bilantia, an apparatus for weighing, from bi, two, and lanx, a dish or scale)

balance of advantages, and the •00 900 000 /0,./O00 so' O0,0000 solution must be obtained by consideration of the special circumstances of each case . It has been found desirable as the demand for the power and the area within which it is supplied has enlarged, not only to increase the number of central stations but also their capacity . The first pumping station erected was installed with 4 pumping engines of goo h.p. each . The pumping capacity of this station has been increased to 7 units . The station at Rotherhithe completed in 1904 has 8 units together 1600 h.p., and the plant at the new station at Grosvenor Road has 8 units equalling 2400 h.p . The pumping stations are situated about 3 M. apart and concurrently with the increase in their size it has been found desirable to intro-duce a system of feeder mains (see below) . There are in all five central stations at work in connexion with the public supply of hydraulic power in London, having an aggregate of 7000 i.h.p .

All the stations and mains are connected together and worked as one system . There are 14 accumulators with a total capacity of 4000 gallons, most of them having rams 20 in. diameter by 23 ft. stroke . The pumping engines are able together to deliver 11,000 gallons per minute . Details of the London supply are given in fig . 3 and in table t . year . Gallons 7 V Eao 0o "-s E O Pumped . ^~ = V L, O a,- e N....-0 e d a o s o o y x se; ., y d 8 3 4.T„5 `--- d. s. d . 1889 163,883,000 0.328 0.524 3'11 10 9 1022 38 1894 400,316,000 0.338 0.553 I.96 10 0 2204 73 f 1898 620,662,000 0.340 0.483 1.98 II 3 3515 109 1903 888,925,000 0.361 0.491 2.7 14 34 5337 146 1909 1,027,147,000 0.354 0.495 2.78 15 I 6504 168 229 The load-factors are calculated on the actual recorded maximum output, and not on the estimated capacity of the plant running or installed . The daily periods of maximum output are shown in fig . 2 . The table shows that the load-factors have not been much affected either by the increase of the area of supply or by the in-creased consumption of power .

The coal used has been principally See also:

• DURHAM
• DURHAM, JOHN GEORGE LAMBTON, 1ST EARL OF (1792–1840)

Durham small . The capital cost of the London undertaking has been about £950,000 . In the central station at Wapping, erected in 1891, there are six sets of triple-expansion, See also:

• SURFACE

surface-condensing vertical pumping engines of 200 i.h.p. each; six boilers with a working pressure of 150 lb per square inch, and two accumulators with rams 20 in. diameter by 23 ft. stroke loaded up to 800 lb per square inch . The engines run at a maximum See also:

• PISTON (through Fr. from Ital. pistone or pestone, a great pestle, from Late Lat. pistare, to pound, a frequentative form of classical Lat. pinsere)

piston speed of 250 ft. per minute, and the pumps are single-acting, driven directly from the piston rods . The supply given from this station in 1909 was approximately 6,800,000 gallons per See also:

• WEEK (from A.S. wicu, Germanic *wikon, probably=change, turn)

week, and the cost for fuel, wages, superintendence, See also:

• LIGHTING

lighting, repairs and sundry station expenses 4.28d. per moo gallons, the value of the coal used being 14s . II.3d. per ton in bunkers . The capital cost of the station, including the See also:

• LAND

land, was £70,000 . The load-factor at this station for 1909 was '49, and the supply was maintained for 168 hours per week . The conditions are exceptionally favourable, and the figures represent the best result that has hitherto been obtained in hydraulic power central station work, having regard to the high price of fuel . The installation in Hull differs little from the numerous private plants at work on the docks and See also:

• RAILWAYS

railways of the See also:

• UNITED

United See also:

• KINGDOM

Kingdom . The value of the experiment was chiefly commercial, and the large public hydraulic power works established since are to be directly attributed to the Hull undertaking . In See also:

• BIRMINGHAM

Birmingham gas engines are employed to drive the pumps .

In See also:

• LIVERPOOL
• LIVERPOOL, EARLS
• LIVERPOOL, EARLS OF

Liverpool there are two central stations . The working pressure is 850 lb per square inch . There are 27 M. of mains, and about Iwo machines at work . In See also:

• MANCHESTER
• MANCHESTER (popularly Manchester-by-the-Sea)
• MANCHESTER, EARLS AND DUKES OF

Manchester and See also:

• GLASGOW

Glasgow the pressure adopted is 'Too lb per square inch . In Manchester this pressure was selected principally in view of the large number of hydraulic packing presses used in the See also:

• CITY (through Fr. cite, from Lat. civitas)

city, and the result has been altogether satisfactory . The works were established by the See also:

• CORPORATION (from Lat. corporare, to form into a body, corpus, corporis)

corporation in 1894, the central station being designed for 1200 i.h.p . Another station has since been built of equal capacity, and nearly 5 million gallons per week are being supplied to work about 2100 machines . Twenty-three See also:

• MILES, NELSON APPLETON (1839— )

miles of mains are laid . In See also:

• ANTWERP
• ANTWERP (Fr. Anvers)

Antwerp a See also:

• REGULAR

regular system of high-pressure hydraulic power transmission was established in 1894 specially to provide electric See also:

• LIGHT

light for the city . The See also:

• SCHEME (Lat. schema, Gr. oxfjya, figure, form, from the root axe, seen in exeiv, to have, hold, to be of such shape, form, &c.)

scheme was due to von Ryssleburgh, an electrical engineer of See also:

• GHENT (Flem. Gent, Fr. Gand)

Ghent, who came to the conclusion that the most economical way of installing the electric light was to have a central hydraulic station, and from it transmit the power through pipes to various sub-stations in the town, where it could be converted by means of turbines and dynamos into electric energy . The coal cost of the See also:

• ELECTRICITY

electricity supplied—o•88d. per kw. See also:

• HOUR

hour—compares favourably with most central electric supply stations, although the efficiency of the turbines and dynamos used for the See also:

• CONVERSION (Lat. conversio, from convertere, to turn or ,change)

conversion does not exceed 40 % . Von Ryssleburgh argued that hydraulic pumping engines would be more economical than steam-engines and dynamos, and that the loss in transmission from the central station to the consumer would be less with hydraulic converters than if the current were distributed directly .

The loss in conversion, however, proved to be twice as great as had been anticipated, owing largely to defective apparatus and to under-estimation of the expense of maintaining the converting stations; and the See also:

• NET

net result was commercially unsatisfactory . At Buenos Aires hydraulic mains are laid in the streets solely for drainage purposes . Each of the sumps, which are provided at intervals, contains two hydraulic pumps which automatically pump the sewage from a small section of the town into an outfall See also:

• SEWER

sewer at a higher level . The districts where this system is at work See also:

• LIE, JONAS LAURITZ EDEMIL (1833—1908)
• LIE, MARIUS SOPHUS (1842–1899)

lie below the general drainage level of Buenos Aires . The average efficiency (pump h.p. to i.h.p.) is 41 %, which is high, having regard to the low heads against which the pumps work . In this application all the conditions are favourable to hydraulic power transmission . The work is intermittent, there is direct See also:

• ACTION

action of the hydraulic pressure in the machines, and the load at each stroke of the pumps is constant . The same system has been adopted for the drainage of See also:

• WOKING

Woking and See also:

• DISTRICT

district, and a somewhat similar installation is in use at See also:

• MARGATE

Margate . Hydraulic power is supplied from the hydraulic mains on a sliding scale according to the quantity consumed . The minimum See also:

• CHARGE
• CHARGE (through the Fr. from the Late Lat. carricare, to load in a carrus or wagon; cf. " cargo ")

charge in London except for very large quantities is Is . 6d. per woo gallons . In woo gallons at 750 lb per square inch there is an energy of 10,000 X 1730 = g 74 h.p. hours; thus Is .

6d. per woo gallons =2d . 33,000 X 60 per h.p. hour nearly . This amount is made up approximately of 9d. per See also:

• I000

I000 gallons for the cost of See also:

• GENERATION (from Lat. generare, to beget, procreate; genus, stock, race)

generation, distribution and general expenses including rates and 9d. for capital charges . The average rate charged to consumers in 1908 was about 2s . 4d. per woo gallons . Even under the most favourable circumstances it does not appear probable that hydraulic power at 750 lb per square inch can be supplied from central stations in towns on a commercial basis over any considerable areas at less than Is. per woo gallons . Allowing ss ss ss n^^^^^^^i.O^^ ^^ IIIIIIIIIIIIIIMIIMMIIIIIIIIIMIIIIIIIMIIIII ^^^^^^^^^^^^^^^^^^^^^^ ^^^^^^^^^^^^^^^.',^^^^ ^^^^^^^^^AIMs^^^^^i^^^ 111^^^^II^^^^^^^^^^^^^^^^^^^ ^ai^^i 111111111111111111111111111111 « ss b p RO r « W s m oe 75 % as the efficiency of the motor through which the power is utilized, this rate would give I.83d. per See also:

• BRAKE

brake or effective h.p. hour . This cost seems high, and it is difficult to believe that it is the best hydraulic power transmission can accomplish having regard to the well-established fact that the mechanical efficiency of a steam pumping engine is greater than any other application of a steam-engine, and that the power can be conveyed through mains without any material loss for considerable distances . Still, no other system of power transmission except gas seems to be better off, and there is no method of transmission by which energy could, at the present time, be supplied See also:

• RETAIL

retail in towns with commercial success at such an average rate when steam is employed as the prime mover . The average rate charged for hydraulic power in London and elsewhere is much the same as the average rate charged for the supply of electrical energy to the ordinary consumer . Gas is undoubtedly cheaper, but in a large number of cases is mechanically inconvenient in its application . Hydraulic pressure, electrical energy and compressed See also:

• AIR (from an Indo-European root meaning " breathe," " blow ")
• AIR, or ASBEN

air (with reheating) can all be transmitted throughout towns with approximately the same losses and at the same cost, because the power is obtained in each system from coal, boilers, and steam-engines, and the actual loss in transmission can be kept down to a small percentage .

The use of any particular system of power does not, however, primarily depend upon the cost of running the central station and distributing the power, but mainly upon the mechanical convenience of the system for the purpose to which it is applied . One form of energy is, in practice, found most useful for one purpose, another form for another and no one can command the whole See also:

• FIELD (a word common to many West German languages, cf. Ger. Feld, Dutch veld, possibly cognate with O.E. f olde, the earth, and ultimately with root of the Gr. irAaror, broad)
• FIELD, CYRUS WEST (1819-1892)
• FIELD, DAVID DUDLEY (18o5-1894)
• FIELD, EUGENE (1850-1895)
• FIELD, FREDERICK (18o1—1885)
• FIELD, HENRY MARTYN (1822-1907)
• FIELD, JOHN (1782—1837)
• FIELD, MAR