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The New Zealand Railways Magazine, Volume 6, Issue 2 (June 1, 1931)

Our London Letter

page 19

Our London Letter

In his present contribution, our Special London Correspondent makes interesting reference to the recommendations of the Automatic Train Control Committee, whose report on signalling in relation to the safety of train travel, was issued recently. He also gives his usual review of current developments on the railways of Great Britain and the Continent.

Signalling and Safety.

The introduction, in recent years, of clever signalling devices of one kind and another, has resulted in a marked increase in travel safety. Power signalling and the employment of day colour light signals are two noteworthy developments in this important field, while the greater use being made of automatic train control systems is minimising the risk of accident. This form of protection is being closely studied by the Home railways, and the recently issued report of the Automatic Train Control Committee, set up by the Minister of Transport three years ago, is full of interest for railwaymen the world over.

In the course of its investigations, this Committee has held no fewer than seventy general meetings and examined hundreds of witnesses including railway operating and locomotive officers, inspectors, drivers, trade union leaders, and manufacturing representatives. After reviewing the various systems of automatic train control, the Committee expresses the opinion that progressive action is desirable for increasing security against accident due to failures of enginemen to observe or correctly interpret signals. They believe that best protection may be secured by the employment of a simple type of automatic control, and by improvements in the conditions under which enginemen work traffic, more especially in respect of lighting and sighting of signals.

To ensure absolute safety, the Committee believe it desirable to provide automatic control at the majority of distant signals and at selected stop signals. For semaphore distant signals, where direct control is desirable, the use of a fixed track ramp and locomotive plunger is recommended. In the case of stop signals (which may be misread by enginemen) used for the protection of trains, starting from or booked to stop, or perform shunting duties at important junctions, stations, or block posts, control at distant signals is of no avail. Protection at selected stop signals is in many such instances desirable. At locations such as these, the Committee recommends the use of a control trip or device of suitable type, catch points or derailers, trap points (with or without sand drags), or detonator placers.

Automatic Train Control.

Various types of automatic train control are employed on the Home railways, a leader in this endeavour being the Great page 20 Western. This undertaking has for some time utilised automatic train control on certain stretches of track, and now the whole of its principal main-lines are to be so equipped. The plan involves the equipment of 1,758 miles of track and 2,000 locomotives with the Company's own arrangement of automatic control. On completion of the new installation, the Great Western will have equipped 2,130 miles of track and 2,334 engines for automatic train control.

For Branch Line Passenger Movement. Latest type of L. & N.E.R. “Sentinel Cammell” articulated steam rail car used on the Home Railways.

For Branch Line Passenger Movement.
Latest type of L. & N.E.R. “Sentinel Cammell” articulated steam rail car used on the Home Railways.

The system gives to the driver audible warning of the state of the signal, and in the event of a danger signal being passed, automatically stops the train before it reaches the next signal. In practice the audible warning is given to the driver when his train is approaching a distant signal in the danger position. In the event of this warning being disregarded, the brakes are automatically applied so as to ensure the train being pulled up before the next stop signal is reached. Another and distinctive audible indication is provided on the locomotive when the distant signal shows “line clear.” For the indication “signal at danger” a siren is sounded, and for the indication “line clear” a bell is rung. The apparatus fixed to the track for operating the audible signals consists of an immovable ramp, forty feet long, placed between the running rails, taking the form of a steel inverted T-bar mounted on a baulk of timber. At its highest point the ramp is four inches above rail level, and it is connected with a switch in the signalbox attached to a lever controlling the distant signal. On the locomotive there is affixed a contact shoe, an electrically-controlled brake valve and siren combined, and an electric bell. The contact shoe is secured on the centre line of the locomotive, projecting to within two and a half inches above rail level.

Rail Cars for Branch Lines.

Steam and petrol-driven rail-cars are a big success in handling branch lines business, although it would be well to bear in mind that, as a result of the growth of the highway motor and the increasing likelihood of branch-line train services being superseded by railway-operated road motor vehicles, the rail motor car cannot seriously be regarded as an absolutely permanent piece of railway equipment. For some years to come there will doubtless be useful openings for the rail motor car, so that the recent move of thé London and North Eastern Railway page 21 in introducing a new type of articulated steam rail car for branch-line operation is of genuine interest.

The new L. & N.E. rail car is of “Sentinel-Cammell” make, and consists of two cars mounted in articulated fashion on three bogies. The motive power is furnished by two 100–125 horse-power engines, one driving the axle of the leading bogie, and the other the trailing axle of the articulated bogie. Gear ratios provide for speeds of 30 or 38 miles per hour at 500 revolutions per minute, the engines, thus being capable of attaining
A Typical Modern Passenger Carriage. Composite (First and Third class) side corridor coach, Great Western Railway, England.

A Typical Modern Passenger Carriage.
Composite (First and Third class) side corridor coach, Great Western Railway, England.

speeds on the level of up to 45 and 60 miles an hour. By the use of dual control, the car may be driven from either end, and on this account it is well adapted to shuttle working. Seats are provided for 122 passengers. The coal bunkers carry fuel for a 150 mile run; and the water tanks have a capacity sufficient for a run of 60 miles. The seats in the two passenger saloons are of the reversible pattern. In recent tests on the level this car attained loaded speeds of up to 65 miles an hour, while on mountain routes its economy in fuel was most marked.

Germany's Novel Rail Car.

While the Home railways, like those of New Zealand, remain loyal to the conventional form of steam and petrol rail car, in Germany a more ambitious line is being taken by developing rail cars driven by aeroplane engines and propellers. The first car of this unique type has been put into service at Hanover, and in its initial trials it attained a speed of 95 miles an hour.

The machine has been built by Herr Kruckenberg, in association with the German Railways, and in exterior appearance the car resembles an airship on rails. A blunt nose contains the driver's compartment, and the silver stream-lined vehicle is 85 feet long. Two running wheels are provided at either end, and an aeroplane four-bladed propeller is situated at the rear. The body is of steel tubing covered with sheet aluminium, the total weight of the car being about 18 1/2 tons. Passenger windows run the full length of the body, and a central entrance door gives access to two compartments, one smoking and the other nonsmoking. The aeroplane engine which forms the means of propulsion is of 500 horse-power. Accessory machinery, an air compressor supplying air pressure, and two electric generators charging the accumulator battery, are driven by the aeroplane motor. This is arranged in the arched fore-point of the car, feeding the lighting and compressor plant and supplying the current for an electric motor which drives the car when the main drive motor is out of action. Two independent braking devices are installed —an external compression brake operated page 22 pneumatically, and a hand brake for emergency use. The new German rail car is in many ways not unlike the “railplane” built in Glasgow by George Bennie. It is doubtful whether rail cars of these novel types will ever prove of real value in actual service, but experimental work such as this is useful in many directions, and the designer of the new German high-speed rail car is certainly to be congratulated upon his ingenuity. (An illustration of a car similar to the one here described was featured in our last issue.—Ed.)

Increasing the Power of Existing Locomotives.

In main-line working, the problem of handling heavier trains with existing locomotive equipment is often a difficult one. Faced with the question of everincreasing loads the Paris-Orleans Railway of France has just put in hand the interesting work of rebuilding several of its “Pacific” locomotives with a view to augmenting their power.

The Orleans locomotives had a relatively large grate area (4.27 square metres), but they were not altogether
A Passenger Train of World Renown. London-Cornwall “Atlantic Coast Express” on the Southern Railway, South Western Main Line, England.

A Passenger Train of World Renown.
London-Cornwall “Atlantic Coast Express” on the Southern Railway, South Western Main Line, England.

satisfactory from the viewpoint of steam production; their superheating qualities were poor; and owing to the wiredrawing occurring at high speeds between the high-pressure cylinder outlet and the low-pressure cylinder inlet, full use was not being made of the steam. The work put in hand included the introduction of the Nicholson siphon to facilitate the circulation of water in the boiler, the enlargement of the ashpan openings to assist the entry of air into the firebox, and the improvement of the draught by the removal of the existing trefoil exhaust, and its replacement by a new type of exhaust with a double smokestack. A Schmidt superheater has also been installed, using 32 large smoke tubes as compared with the 24 tubes formerly employed. Lentz-Dabeg valve distribution has also been introduced; the throttle valve, steam intake pipes, high-pressure steam chests and by-pass cut-offs have been increased in section to get rid of wiredrawing; and mechanical lubricators installed for the driving mechanism and driving and coupled axles. Increase of power amounting to as much as fifty per cent, has been secured, and fuel consumption has been considerably reduced.