During the last decade of the 19th century, trains powered by electricity began to appear. Since there was no fire for a fireman to attend, it was logical that only one man was needed in the cab. However, it was thought that there should be some way of ensuring he always kept alert and, indeed, that he always stayed in the cab while the train was running. It therefore became usual to provide some sort of vigilance device.
The vigilance device was originally installed to cover the situation where a driver collapsed due to illness whilst in charge of a train and it usually consisted of a spring loaded power controller handle or button. It therefore quickly became known as the "deadman's handle". More recently it has become known as a vigilance device or "driver's safety device" (DSD). In France it is called "VACMA", short for "Veille Automatique de Contôle à Maintien d' Appui".
There are three types of deadman devices; a spring loaded master controller handle, a spring loaded pedal or an "alerter". The deadman's handle usually requires constant pressure to maintain operation. If the handle is released, the brakes will apply. The pedal requires operation at regular intervals. One minute seems to be the normal time allowed between pedal depressions. An audible "warble" warns the driver that he must depress the pedal within 3 seconds. For an "alerter", the key thing is positive movement of the controls: if you don't move something occasionally, the alerter will come on and you have to acknowledge it. If not, it will cause a penalty brake application. This is the popular system in the US. In some countries, a push button is provided in place of the alerter system.
French railways used to favour a ring fitted round the controller handle. You have to grip the ring and lift it against spring pressure to keep the brakes off. There is a time delay, essential as most of the driving positions are in the centre of the cab away from the side windows. Of course, you need to look out of the side window sometimes for shunting, coupling and so on. It's not much good if you can't hold on to the "deadman" and there's no time delay.
In order for two railway vehicles to be connected together in a train they are provided with couplers. Since there are a large number of railway vehicles which might have to be coupled at one time or another in their lives, it would seem sensible to ensure that the couplers are compatible and are at a standard position on each end of each vehicle. Of course, life isn't as simple as that, so there are a variety of different couplers around. However, there is a high degree of standardisation and some common types have appeared around the world.
The simplest type of coupler is a link and pin. Each vehicle has a bar attached to the centre of the headstock (the beam across the end of the vehicle, variously called the end sill or pilot in the US) which has a loop with a centre hole attached to it. Each coupler has a bellmouth around the end of the bar to assist in guiding the bar with the hole into place. The loops are lined up and a pin dropped into them. It's not very sophisticated but it was used for many railways during the 19th century and has persisted on a few remote lines to this day. There were some variations on the idea and here is a good description with photos and drawings
The next type of coupler is the bar coupler. This is what is known as a semi permanent coupler. It cannot be disconnected unless the train is in a workshop and access underneath the train is available. It is normally used in EMUs which are kept in fixed formations of two, three or four cars. The bar couplers are located within the unit, while the outer ends of the unit have some type of easily disconnected coupler. Bar couplers are simple, just consisting of a bar with a hole at the inner ends through which the car body is connected by a bolt. Others consist of two halves which are just bolted together as shown in this example:
This type of railway coupler is exactly what it says - a set of three links which are hung from hooks on each vehicle. A development of this is the "Instanter" coupler, which has a middle link forged into a triangular shape to allow the distance between vehicles to be (crudely) adjusted. This is to allow the side buffers used with the coupler to be adjacent to each other and provide some degree of slack cushioning.
The coupler required a person to get down on the track between the two vehicles and lift the coupling chain over the hook of the other vehicle. Sometimes a "coupling pole" was used for quickly uncoupling freight wagons.
This photo shows a screw coupler in the uncoupled position. This is a development of the 3-link coupling where the middle link is replaced by a screw. The screw is used to tighten the coupling between the two vehicles so as to provide for cushioning by compressing the side buffers. The following photos show typical screw couplings.
The photo on the left shows a coupled screw coupler also showing typical fittings of passenger vehicle coupling In addition to the mechanical couplings required to connect the vehicles, trains had to have through connections for brakes, lighting and heating. In this photo, the arrangements for coupling two passenger coaches in a steam hauled train are shown. Note that this particular type of coach was provided with safety chains, which were fitted in case the main coupling broke. Of course, all the work involved in connecting the two vehicles was carried out manually. It is hard work and sometimes dangerous. It is still common in the UK and Europe.
By far the most common coupler seen around the world is known variously as the "Knuckle", "Buckeye" or "Janney" coupler, diagram left. This is an automatic, mechanical coupler of a design originating in the US and commonly used in other countries for both freight and passenger vehicles. It is standard on UK hauled passenger vehicles and on the more modern freight wagons. The term "Buckeye" comes from the nickname of the US state of Ohio "the Buckeye state" and the Ohio Brass Co. which originally marketed the coupler. It was invented in 1879 by a US civil war veteran named Eli Janney, who wanted to find a replacement for the link and pin couplers then standard in the US. Link and pin coupler required staff to stand between cars to couple and uncouple and there were many injuries and even deaths as a result. Janney's invention solved these problems and was taken up by a number of lines. The device eventually became standard when the link and pin coupler was banned by the US government in 1900.
The railway coupler (shown above) is made of cast steel and consists of four main parts. The head itself, the jaw or knuckle, the hinge pin, about which the knuckle rotates during the coupling or uncoupling process and a locking pin. The locking pin is lifted to release the knuckle. It does this by raising a steel block inside the coupler head which frees the knuckle and allows it to rotate.
The simplified animated diagram below shows the steps when two couplers are being coupled.
To couple two vehicles, the knuckles must be open. When the two vehicles are pushed together, the knuckles of the two couplers close on each other and are locked from behind by a vertical pin dropping a steel block into place behind a raised casting on the knuckle. To uncouple, one of the pins must be pulled up to release the block locking the knuckle. This is done by operating a lever or chain from the side of the vehicle.
More and more railways are using fully automatic couplers. A fully automatic coupler connects the vehicles mechanically, electrically and pneumatically, normally by pushing the two vehicles together and then operating a button or foot pedal in the cab to complete the operation. Uncoupling is done by another button or pedal to disconnect the electrical contact and pneumatic connection and disengaging the coupler mechanically.
Fully automatic couplers are complex and need a lot of maintenance care and attention. They need to be used often to keep them in good working order. There are a number of different designs in use. Two are shown here. Click on the images to enlarge and read the descriptions.
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