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5. The construction is very cheap. a weight could be mounted on the floaty

6. Combination of a time and latitude thus enabling us to move the center of instrument in one.

gravity of the floating part, and to tilt 7. It admits also, of the application of the axis of the telescope. We can thus a delicate micrometer on an entirely new apply here the same methods that we principle, as a micrometer screw carrying can in the zenith telescope.

THE BEHAVIOR OF RAILWAY CARRIAGES IN PASSING

CURVES.

By F. HOFFMANN.

Foreign Abstracts of the Institution of Civil Engineers.

R+s

or=

or for

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176) ... (1) of both axles,

GS is due to transverse sliding, the wheel-base were < the gauge. Less

THE author draws attention first to

R

thus a=b= the case of a simple wagon with rigid

; (3) for either axle in wheel-base, and on each of whose axles outer contact, and the other on the midtwo wheels with coned tires are immov- dle of the line; (4) for a diagonal posiably fixed. He gives the most general

1 R

R+8 form of equation between work and tion, thus a=

6- R + 8 R resistance on a curve, and thence derives

the the form it takes in practical cases, viz., line, thus a=:b=1; (5) for inner contact

wagon set fairly on the middle of the L 1-a 1-6

R +8 K=G +

thus a=b=
R R

1+ a
1+6

R where K is the resistance, G whole load For investigation of actual resistances on one axle, f coefficient of friction, L and wear, the position assumed by the wheel base, Ř radius of a curve, s the wagon under the conditions that generwidth of gauge from center to center of ally hold in practice must be ascertained. rails, a ratio of running radius of inner Experience proved that the front axle of to that of outer wheel on front axle, and a wagon with rigid wheel-base always b the same ratio for hind axle. The part ran in outer contact. Theory shows L

hat it could only be otherwise if the R

wheel-base rest to the rotation of one wheel about was known of the behavior of the hind the other on each axle. This expression axle; to solve the question trials were shows that the resistance is small for made on a line with curves of radii down light load, smooth rails, narrow gauge, to 81 chains, with wagons of 16.4 and short wheel-base, large radius of curva- 8.2 feet wheel-bases, in which an arture, and values of a and b near the limit rangement of mirrors showed the play R

between flange and rail to occupants of R +8

the wagon. It was found that the ten

dency of the hind axle to run in inner Of the equations

contact was much greater for the long L

than for the short wheel-base; for the (2) latter indeed it ran in outer contact

when the curvature was small. Reasons K=Gf

(3) are then given for assuming the law, R 2R

that the hind axle of a four-wheeled L

wagon with rigid wheel-base always R

(4)

takes a radial position if sufficient play L 2s

be provided on the line. Its accuracy (=Gf

(5) was confirmed by experiments with a + R R

model. Hence the distance between (2) holds for both axles in outer contact,'outer rail and outer flange of hind axle

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sin ß

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being the height of a chord equal to 1,=$, and the second member may, in twice the wheel-base is

most cases, be neglected. K, and K,

have not, to the author's knowledge, on=

(6) been taken into account hitherto. K 2R

L'

arising from horizontal shifting causes but if o the wbole play be < then: wear of the rail tops, and affects the

2R'

inner rail most; K, causes wear of the On=0

(7) axle seats and holders only; K, resemand corresponding to these values of on bles the action of a blunt cutter, the we have for the sine of the angle of con- flange of the outer front wheel being the tact of outer front wheel

cutter, and the inside of outer rail the L

object cut. For carriages in a train the sin ß=

(8) value of Pais altered by forces in the R

couplings, and the author investigates L

this effect minutely.

(9) 2R L

Dealing next with six-wheeled carThe constraint necessary to alter the riages, if to the middle axle no more position of a wagon turning a curve than the necessary play be given by arises partly through the axle seats, but thin flanges, cylindrical are better than chiefly from the lateral pressure

between

conical tires; but with the usual spread the rail and the outer flange of the front of gauge at curves no lateral play is axle. For the former the maximum value required for the middle axle. If there d

be no spread of gauge, safety requires is K =Gf û xfi 27, where f, is coeffi- a lateral play of 0.2 inch only for a cient of friction between axle and axle- wheel-base of 19.7 feet would require 0.8

wheel-base suited to the curve; but a seat, d diameter of an axle-arm, and 1 inch on a curve of 8.5 chains radius. radius of a wheel; this is a consequence of the geometrical connection of the Supposing the loads G on the end

axles axles and wagon. The expression for equal, and that on the middle axle a the lateral pressure is

fraction n of each of these; so that, Q being the weight of the carriage, Q

nQ 1+

G

the whole rePa=G 2L V? 1h

to tana)
cos ß
gR

sistance is
where V is the velocity, g the accelera- for inner contact of middle axle:
tion for gravity, h the cant of outer rail,
and a the angle of conicity of the tires :

( (L+8) +n +8 Qf

(11) here no allowance is made for friction K''. between flange and rail, but if s, be the

R

n+2 coefficient, and the actual place of con- for outer contact of middle axle: tact be considered, we have for lateral 0.9 sin ß

L pressure, K,=

Pax J
The

(L + 8) +n

) Qf

2

(12)

K'= three members of Pa are due to the force

R

n+2 to make the front axle take its altered position, centrifugal force, and the force Comparison of these equations with (4) arising from cant. The total curve re

shows that a six-wheeled rigid-axled carsistance is Ky=K+K,+K,, and for a

riage passes curves with less resistance diagonal position of the wagon with the than a four-wheeled one of equal weight front axle in outer contact, which is the and wheel-base, if the middle axle can position occurring in practice,

run in outer contact, but with greater if

its play allows only of inner contact. Ky= =GT +

The minimum lateral play required to
R
R

allow the middle axle run in outer cond

L’ o xfit

+

8R 2 where the values may be f=}, fi=its, The cant of the outer rail, when

and Gm=

n + 2

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n+2'

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+

.

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r

0.9 sin B Paf, ... (10) tact is

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V?
GR

up with

adapted to neutralize centrifugal force, comotive, a bogie be used in front, with is obtained from the equation

a rigid axle behind, the resistance,

though less than for a rigid four wheeler, h=8 - o tana

na). ... (13) is large compared with the value just After treating generally of the ques- axle have the disadvantage of complica

given. Since bogies with more than one tion of spread of gauge, the author sums tion, and for locomotives of reducing the conclusions : -1. Four

the load on the front outer wheel, numerwheeled wagons with rigid wheel-base

ous systems of flexible single axles have pass curves with greater safety when

been devised. Of these the Adams there is no spread of gauge, and the flanges are unworn, since the angle of locomotives, have been laid aside on ac

guided axle, and the Bissel front axle for contact is then diminished by half: 2.

count of their dependency for steady Such wagons run on curves of the mini

motion on the presence of two rigid mum radii for their wheel-bases, and

axles of long wheel-base. with the usual spread of gauge, with the

Mr. John Clark devised a three-axled hind axle in inner contact, and with less constraint than if there were no spread the axle boxes were so connected by

wagon, used on Mount Cenis, in which of gauge: 3. With the usual spread of mechanism that the yielding of the midgauge the curve resistance is less for worn-out than for unworn tires.

dle axle through the height of a chord Security is dependent on the relations equal to the wheel-base caused the end existing for the outer front wheel, and is

axles to run radially. If i denote the greater--the greater the vertical, the yielding of the middle axle, ø the anguless the lateral pressure, the smaller the

lar turning of the end axles, since L’

L angle of contact, and the more sharply 1= and sin 0= the condition to rounded and vertical the places of con

8R

2 R' tact between flange and rail.

be fulfilled by the mechanism is sin The curve resistance and wear are λ less—the less the vertical and lateral $=4î, which shows that it will suit pressure, the less the angle of contact,

curves of any radius. With this, and and the nearer the places of contact be

the Cleminson system on the same printween flange and rail lie to the crown of the rail, and for the least possible round- ciple, the curve resistance and lateral ing of these places.

pressure can be almost totally removed.

For a locomotive with the Nowotny À table is given with corresponding front axle, which differs from the Bissel values of R, L, V, h, o, p, lateral press- axle in having the pivot above the midure, and total curve resistance of four- dle of the line joining the wheel centers, wheeled wagons and locomotives with instead of being somewhat behind this rigid wheel base. Arrangements for facilitating the use duration of the front tires, and propor

position, experience has shown that the of longer carriages on curves are next tionally of the rails, is four times > for a considered. When a carriage constructed on the American bogie system runs wheel-base.

rigid axled locomotive of the same on a curve, each car will clearly follow a

In the search for a simple system of tangential direction till it runs against flexible axles for wagons, the central the outer rail, and then assume the posi. pivot being laid aside, an arrangment altion natural to a rigid-axled wagon. lowing the journals with their covers to Owing to the smallness of the distance slide in the long direction of the wagon 1

(2 being the bogie wheel base) of the against single or double incline seats in 2 R

the boxes, with a central holder to neuhind axle of each car from the outer rail tralize shocks, was adopted with success. equation (2) holds approximately for A simpler method lay in providing suiteach ; hence the whole curve resistance able play between axle box and holder, to produce the altered direction of the with the necessary turning power be

L carriage is 2 Gf G, being the load tween bearing spring and axle box. R'

Several forms of couplings for flexible on a single car axle. If, again, for a lo- axles are shown by drawings.

ON THE CONSTRUCTION, PERFORMANCE, AND WORKING

OF LIGHT RAILWAY LOCOMOTIVES.

By Hr. VON BORRIES, of Hanover.

Foreign Abstracts of the Institution of Civil Engineers. This is an essay towards settling the luggage or passengers as part of their conditions, leading dimensions, &c., of load.* A four-coupled engine is to be engines for working “secondary” or preferred, unless the traffic is heavy, or light railways, based on the general prin- the conditions unfavorable. The train ciples laid down in Germany for the con- officials should be reduced in number as struction of locomotives, and the building far as possible, since each may be taken and working of light railways. Three to absorb in wages from 6 to 15 per cent. different gauges are considered through of the working cost. On light railways out, viz. : standard gauge (4 feet 8} the full services of both driver and fireinches), meter gauge (3 feet 3} inches), man are not needed for the engine, and and meter gauge (2 feet 5 inches). therefore the latter may also act as a

Load per Axle.This is the first ele- brakesman, working not only the engine ment to be fixed in all rolling stock. In brakes, but also those in the front van, light railways the rails are proportioned which should be placed in communicato the heaviest goods wagon which will tion with the engine. The guard would run on the line, and the weight per axle also act as a brakesman for his own van, of the locomotive must conform to this. which should always be at the rear of the With standard gauge, where main line train, and no other brakesman would be wagons may come over the line, the load necessary. Continuous brakes are not per axle should be taken at 9 tons; with worth their expense, especially looking meter gauge at 74 tons ( taking 10 tons to the probability of goods wagons being as load of wagon, and 5 tons as its mixed in the train ; but, as a provision weight); with 1 meter gauge at 3} tons for emergency, such goods wagons may (5 tons' for load, 24 tons for weight of be fitted with lever brakes on the Exter wagon). These figures agree with the system, which may be worked from the rules of the German Railway Union, ex- engine by means of a cord. The engines cept that they give 5 tons for meter should have a gangway at each side, and gange, which seems excessive.

provision at each end for stepping on to General Principles. — The leading an adjoining vehicle. principles should be simplicity of con Provisions against Fire and against struction and facility of maintenance. the frightening of Horses.—The danger The blast pipe should be retained, as the of fire must be completely obviated by most economical and automatic method proper spark catchers or extinguishers, of forcing the fire, and the condensation and by closing in the ash pan, so that no of the steam, sometimes insisted on in pop- cinders can escape. Horses are found ulous districts, should be avoided as much to be frightened mainly by the sight of as possible, on account of the expense. a carriage, apparently running of itself, The engines should be tank engines, by violent puffs of smoke or steam (not four-coupled or six-coupled, according the mere escape of steam at the chimto the work to be done. They should ney), and by rapidly moving gear. These be no heavier than is required to produce causes can be removed to a great extent, the requisite tractive force by adhesion, if not entirely, by boxing up the gear, and the speed on steep gradients should by placing an air vessel in the exhaust be lowered so that a boiler suited to this pipe, and by turning the escape from the weight may generate the needful amount cylinders and safety valves into the con. of steam. For very steep gradients, the requisite weight may be obtained by

* Vide Minutes of Proceedings Inst. C.E., Vol. Ixi., using special engines, designed to carry 369 " Van Locomotive."

p.

denser, and that from the injector into as 3 feet 3 inches, the same as for the carthe tank.

riages, which, at 18 miles an hour, the Leading Dimensions. The engines maximum speed, gives 2.8 revolutions per are taken to weigh about 90 lbs. per second. For the narrow gauges the square foot of heating surface ; it being speed should not exceed 12 to 15 miles assumed that they are built on the Krauss an hour, and the diameter of the wheels system, and that the grate surface and may be from 2 feet to 2 feet 8 inches. tank capacity will be varied according to the length of stroke should be about the gauge. The useful steam generated half the wheel diameter. The cylinder is taken at 5 lbs. per square foot of heat- diameter may be calculated (for metric ing surface per hour, with a pressure of measures ) from the following equation: 150 lbs. The latest cut-off, on the steep

Tractive force est gradient, should not exceed 0.4 of d =0.011 x

where 0.011 the stroke, which gives mean pressure =

3.4 97 lbs., and work done per pound of is Koch's value for the co-efficient of steam =

102,000 foot-lbs. The adhesion machine friction in locomotives. The co-efficient, with sanded rails, may be grate surface should be as large as postaken at 0.15; whence, assuming that the sible, say to heating surface for standard engine may lose 11 per cent. of its full gauge, o for meter gauge. The tank weight, through consumption of fuel and may hold 3} cubic feet, and the bunkers water, the tractive force may be taken as 1.1 cubic feet, per ton of engine weight. 0.133 of the full weight. The wheel di- The above and other leading particulars ameter for standard gauge may be taken are combined in the following table:

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Performance of the Engines on va- dients below the steepest at a proper rious Gradients. The various figures limit; the principle being that the gen. assumed above give an effective power eration of steam should never be faster for the engine of about 6.3 HP. per ton than it is on the steepest gradient. If weight. The tractive force per ton this gradient is greater than 1 in 100, weight, including friction, will be about the evaporation, with lighter gradients 321 lbs., whence it is calculated that the and higher speed, will remain about the speed required to develop the maximum same. If it is less than 1 in 100, the tractive force is 7 miles an hour; and evaporation diminishes rapidly on lighter this should therefore be taken as the gradients, and the speed must therefore speed on the steepest gradient of the be regulated by some positive limit, line. On this assumption the maximum which in Germany is 18 miles an hour. haulage load on various gradients, exclu The gross consumption of water per sive of the engine, is given by the table hour may be taken at 6.5 lbs. per square on next page.

foot of heating surface, or 0.075 of the Working.The cost of fuel and re- weight of the engine. The total weight pairs may be greatly diminished on light of water in the tank may be taken at 01 railways, by keeping the speeds on gra-l of the engine weight; and, assuming

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