RAILWAYS 



Freight wagons and vans are of 

 many types and capacities. The 

 majority of open wagons used in 

 Great Britain are four-wheeled, 

 have a tare (weight empty) of 6-7 

 tons, and carry loads of 10-12 

 tons. Bogie wagons for coal and 

 ore take up to 40 tons, and special 

 vehicles are provided for the trans- 

 port of exceptionally heavy loads, 

 such as large castings, guns, and 

 girders. In the United States, 

 where the " long haul " is the rule 

 rather than the exception, the long 

 50-ton car, built almost entirely of 

 steel and carried on bogie trucks, 

 is becoming the standard for hand- 

 ling most kinds of freight. Speak- 

 ing generally, the weight of a 

 wagon relatively to that of its load 

 decreases with size, and the em- 

 ployment of large wagons reduces 

 the dead or non-paying load to be 

 hauled. There are serious difficul- 

 ties in the way of introducing very 

 long wagons for general service 

 in England, weigh-bridges, turn- 

 tables, etc., having been designed 

 for short rolling stock. 



Combined Engines and Cars 



The combined locomotive and 

 passenger car has been found useful 

 in districts where the traffic is too 

 small to justify an ordinary train 

 service. Most vehicles of this kind 

 have a small steam engine and 

 boiler at one end, driving the 

 wheels immediately below. A 

 boiler of the locomotive type is 

 used in most cases. The cars are 

 40-75 ft. long and seat 40-75 

 passengers. Petrol-driven cars are 

 in service on the N.E., London & 

 N.W., and Midland G.W. (Ireland) 

 Rlys., and the G.W., N.E., and 

 G.C. have some in which power 

 developed by a petrol motor is 

 transmitted electrically to the 

 driving wheels. In motor train sets 

 an engine is attached to one or 

 two carriages, or a couple of car- 

 riages may be placed on each side 

 of it, and arrangements are made 

 so that the actual driving can be 

 effected from each end, a stoker 

 attending to the engine. Thus the 

 need is avoided of detaching the 

 engine and shunting it to the head 

 of the train at terminal stations. 



ELECTRIC RAILWAYS. The work- 

 ing of rlys. by electric traction, in 

 which the trains are driven by 

 current conveyed through fixed 

 conductors, placed beside or above 

 the rails, to motors mounted either 

 in the cars or in a separate loco- 

 motive, has made great strides 

 within the last generation. The 

 conditions which invite its adop- 

 tion are found especially on urban 

 and suburban lines, where the 

 traffic is dense, the trams frequent, 

 and the stations closely spaced. 

 Owing to the fact that the electric 



6473 



motor has much greater powers of 

 acceleration than the steam loco- 

 motive, a higher average speed can 

 be obtained, and thus the capacity 

 of the line is increased. Another 

 factor is that it increases the ca- 

 pacity of terminal stations. 



The time and expense of shunt- 

 ing a locomotive from one end of a 

 train to the other, or of providing 

 a second one with the lines and 

 sheds necessary for its accommo- 

 dation, are saved, since an electric 

 train, with its cars fitted with 

 motors, can run in either direction 

 and be driven from either end. 

 Again, with rlys. in town areas 

 that run wholly or partially in 

 tunnel, electrification greatly sim- 

 plifies the problem of ventilation. 

 It is not, however, confined to 

 suburban rlys., and many examples 

 could be quoted of its application, 

 accomplished or proposed, to main 

 lines over long distances, especially 

 in countries where fuel is scarce, 

 but water-power is available for 

 the generation of electricity. In 

 England the N.E. Rly., which pro- 

 vided the first instance in the 

 country of the working of mineral 

 traffic by electricity (Newport- 

 Shildon line, 1916), announced, in 

 1919, its intention of electrifying 

 its main line between York and 

 Newcastle. 



Types of Current Employed 



Both direct and alternating cur- 

 rents are employed for electric 

 working. In Great Britain the 

 former predominates, the only con- 

 siderable example of alternating 

 current (single phase) being pro- 

 vided by the system of the London, 

 Brighton & S.C. Rly. In the earlier 

 lines the direct-current voltage 

 used was 600, but a pressure of 

 1,200 volts has been adopted on 

 the Manchester-Bury section of 

 the Lancashire & Yorkshire Rly., 

 and 3,000 volts has been reached 

 in America. A committee ap- 

 pointed by the ministry of trans- 

 port has recommended (1920 and 

 1921) that 1,500 volts direct- 

 current be the standard system for 

 the United Kingdom, subject to the 

 retention and, if thought advisable, 

 the extension of existing voltages, 

 and also to the adoption of multi- 

 ples or sub-multiples of 1,500 volts. 



TUBE RAILWAYS. London has 

 a unique electric rly. system in its 

 seven "Tube" rlys., so called 

 because the tunnels are circular 

 and lined throughout with iron 

 segments bolted together to resist 

 pressure of ground and exclude 

 water. They were driven at a 

 great depth in the clay (70-180 ft. 

 below from the surface) to avoid 

 interfering with existing sewers, 

 water and gas mains, and tunnels ; 

 and in three cases they pass under 



RAILWAYS 



the Thames. Each track runs in its 

 own tunnel, the two being abreast 

 at the same level, except where the 

 right of way overhead is too narrow 

 to permit this. 



Connexion with Termini 

 In some cases the stations are on 

 summits approached by a rising 

 gradient of 1 in 60, which slows the 

 train automatically, and are left 

 on a falling gradient of 1 in 30, 

 which quickly accelerates the 

 trams with very small consump- 

 tion of current before the level 

 stretch between gradients is 

 reached. The various tubes com- 

 municate by subways with one 

 another at crossing points, and 

 with most of the great rly. ter- 

 minals. At Paddington, Liverpool 

 Street, Charing Cross, and other 

 points passengers are moved to and 

 from the tunnel stations by esca- 

 lators or travelling staircases (see 

 Escalator). The City & S. London 

 line, the first tube rly. in London, 

 was originally made with tunnels 10 

 ft. 2 ins. in diameter, afterwards 

 enlarged to 11 ft. 8J ins. diameter, 

 while those of the Great Northern 

 & City measure 16 ft. The other 

 five lines have tunnels about 12ft. 

 across. At sharp curves the dia- 

 meter is slightly increased to give 

 clearance for the long bogie cars. 



RACK RAILWAYS. On gradients 

 exceeding 1 in 25 the ordinary kind 

 of adhesion locomotive becomes 

 impracticable. Gradients up to 

 I in 12 can be climbed, under 

 favourable conditions, by trains of 

 which all the wheels are driven. 

 On steeper grades adhesion is in- 

 sufficient, and a positive means of 

 haulage is required, the most usual 

 being that afforded by the engage- 

 ment of driven cogwheels with a 

 rack laid between the running 

 rails and fixed firmly to the 

 sleepers. The steepest rack rly. yet 

 built is that up Mt. Pilatus, with 

 an average gradient of 1 in 2^ and 

 a maximum gradient of 1 in 2. 

 This, however, is an exceptional 

 case, as 1 in 4 is considered the 

 ordinary limit, above which cable 

 haulage is to be preferred. 



The racks used are of several 

 kinds. The Strub is a single strong 

 flat-footed rail with large teeth cut 

 in the head ; the Riggenbach has a 

 single set of teeth shrouded on 

 both sides ; the Abt, two or more 

 sets so arranged that the teeth are 

 in different lines transversely. The 

 last gives the smoothest running, 

 as at least two rack teeth are 

 always engaged with a driving cog. 

 Various devices are employed to 

 prevent the cogs climbing the 

 teeth of a rack. On very steep 

 gradients the locomotive is always 

 placed on the downhill side of the 

 vehicles it has to move. Brakes 



