ailways were a formalised development of industrial tramways, which had found need on occasions to add additional braking capacity by adding an empty truck to the rear of a group of tramcars. This allowed the "locomotive" — often a cableway powered by a steam engine at the surface — to operate both safely and, more importantly, at higher speed. The first railways, such as the pioneering Liverpool and Manchester Railway of 1830, used a version of the tramways buffer and chain coupling, termed a screw-coupling. Vehicles are coupled by hand using a hook and links with a turnbuckle-like device that draws the vehicles together. Vehicles have buffers, one at each corner on the ends, which are pulled together and compressed by the coupling device. With no continuous brake across the entire train, the whole train was reliant on the braking capacity of the locomotive, and train lengths were restricted. To allow for longer trains, early railway companies from the 1840s onwards began replicating industrial tramway practises, by adding "break vans". The term was derived from their name on the industrial tramways, in which they controlled the (residual) train if there was a "break" in the linkage to the locomotive.[citation needed] Early railway couplings had been found to be prone to breakages. The term was only replaced by "brake van" from the 1870s onwards. Because of the combined risks of shortage of brake power and breaking couplings, the speed of freight trains was initially restricted to 25 mph (40 km/h). The brake van was marshalled at the rear of the train, and served two purposes: Provided additional braking for 'unfitted' goods trains Put a man (the guard) at the rear of the train, who could take action in the event of a breakdown or accident While the UK railway system persisted until post-nationalisation in 1948 with "unfitted" (discontinuously braked) trains and loose couplings (the final unfitted trains ran in the 1990s), other systems, such as the North American adoption of the Janney coupler, overcame the same railway safety issues in a different manner. The guard's duties This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (January 2015) (Learn how and when to remove this template message) On unfitted trains, the brake van has several purposes, and hence jobs for the guard: Operating the brake, train supervision, and illumination & communication. Firstly, and most importantly, the guard would use the brake van's brakes to a