Tyers Electric Train Tablet

The Electric tablet system is a block system for single-track railway lines. It was developed by Edward Tyer (1830-1912) and in 1880 patented. Since it against its predecessor systems, the operating safety of railway traffic significantly increased, the Tyer system was widespread after a few years, especially in Great Britain and the former colonies. It comes in Sri Lanka is still used. Even with single-track heritage railway lines, it is still used today, such as the North Yorkshire Moors Railway in northern England. The production and worldwide distribution was carried out by Tyer & Co.

Concept

The Electric tablet system is a design of the "Electric Token Block". As with other block systems, the route is divided into block sections. A train may only enter a block section if the train driver is in possession of a token, which gives him the license. When Tyer system take tablets this function. These tablets are removed from tablet devices, each of which is placed at the beginning and one at the end of the block portion. The apparatuses are electrically connected with each other so that, for each block only a portion of a tablet can be taken from the apparatus. Before a tablet can be drawn, a release must be made, which disables this apparatus on the line at the end of the block section. With the removal of the tablets and the apparatus at the beginning of the block section is locked. The next tablet can only be removed when the train arrived at the end of the block section and the block was released by returning the tablets.

Components

Tablet Apparatus

A Tyer apparatus consists mainly of a closed box made ​​of wood or metal with two sliders for removal and return of the tablets. Communication with the operator of the other apparatus is done with a button (" Bell " ) at the top of the box, with the bell can be triggered at the remote site. A second button (" Switch" ) unlocks the removal slider on another phone or returns the removal slide freely on your own telephone. An ammeter indicates whether the electrical connection between the apparatuses is intact. If the block is free or occupied and for which the direction of travel of the block is enabled is displayed in a window at the front of the box. In each case, a tablet may, after approval by the other party - the same principle as with the cigarette - be pulled over the sampling valve at the bottom. Thus, the apparatus is automatically locked. The tablet from the incoming train is returned via a second valve at the top to be released and the lock. In the box there is space for about 20 tablets, the current number can be read through a window at the front.

The devices were initially set up in the stationmaster's office, these days they are usually located in the switchboard. You must only be used by the Dispatcher. If multiple units are placed in a room, the bells for better recognition have a different sound.

Tablet

Tablets as brass round discs with a diameter of about 10 - 12 cm is used. On each tablet, the section for which it is valid, and a serial number is printed or stamped. After taken out, it is inserted into a leather bag, which is attached to a brass ring with a diameter of about 60 cm. With the ring the surrender of the tablet is facilitated on a moving train. Tablets have in the middle of a larger round, triangular or square hole, a smaller round hole near the edge and a semi-circular, rectangular or triangular notch at the edge. The Tablets of the individual block sections differ, to avoid confusion, in the form and arrangement of the holes and notches. You can only be inserted into the apparatus, which belong to the same block section.

In later years there were square tablets and those which were made of aluminum or plastic.

Connecting line

The two belonging to one block portion apparatuses are electrically connected to each other via the telephone line or telegraph line. Thus, no special wiring is required for the route block. The change between block and phone carried by a particular bell signal.

Handling

If no train on the track, the removal of both slide sets are semi- open, all tablets are in the apparatuses and it can not be removed Tablet. Before a train is scheduled to run, calls the station of departure with the Bell button on the share. The request is acknowledged with the Bell button. Then the removal of the two sets slider is closed and the apparatus of the destination station, the switch button is pressed, what where it triggers a lock of the sampling valve and the station of departure clears the sampling valve. By pressing the switch button on the own apparatus, the station can now remove a tablet at the output station. With the removal of the apparatus is also locked at the departure station and up to the arrival of the train, no further tablets are drawn.

The number of tablets is listed in Zugmeldebuch and station board shall give the signal guards the order to make the exit signal. The tablet is put into a leather bag and handed over to the train driver as a driver's license. This checks whether the tablet for the next route section applies and the train continues its journey. At the destination station of the train driver passes the tablet the station master and receives the tablet for the next section.

The block release takes place by the tablet is returned at the destination station using the slider at the top.

Development, types and distribution

Two frontal collisions, the railway accident at Thorpe in 1874 and a second in Radstock in 1876, had shown that the block telegraph system used hitherto been subject to significant safety deficiencies. The development of the Electric tablet system arose from the desire to eliminate these deficiencies and to increase the reliability on single-track lines.

Over the years, the system was further developed and modified for special requirements. Widespread was the design no. 3 from the year 1890. With the rare design no. 5 (1891 ) were able to run two consecutive moves in one direction. Prior to the development of type no. 6 in the 1892 block of the section could only be released by returning the tablets at a neighboring instrument. In the design no. 6 could also be returned to the tablet at the same instrument. This could be secured with the system also trains that do not lead to the end of the block portion, but came back on the road. To patent the design no. 7 in 1898 ended the development of tablet Electric Systems, and easier -to-use token systems were key to the succession.

In later years, the installed equipment have been retrofitted, the most important change was the coupling of the exit signals with the block devices and in many places the relocation of the equipment of the station buildings in the signal boxes. In the UK, the Tyer system was largely replaced by the end of the 20th century. In countries that began British signaling, such as in New Zealand, Australia, Japan and Indonesia, the Electric tablet system was also used. In Sri Lanka, the operation is still carried out on parts of the network with the Electric tablet system.

Pros and Cons of Electric Systems Tablet

The Electric Tablet system has over the older rod system has the advantage that several trains without effort can go one by one, that between the operating points ensures a safe and understanding that no special wiring is required by the use of the telegraph line. The modes can - in contrast to the block telegraph previously used - can be read at any time on the phone.

The greatest disadvantage especially the older designs is the lack of dependence between exit signals and block apparatus, ie, it was possible to make the exit signal to " drive ", although the block was occupied. As the railway accident of Abermule shows, the Electric tablet system was not a substitute for the care and discipline of the operating railway workers.