Saddle tank (submarine)

Saddle tanks are a type of ballast tank configuration fitted to mid-era submarines, those of World War II.

Saddle tanks are fitted in pairs external to the pressure hull, one on each side, in a similar manner to that of a horse's saddle-bags, the positioning of which they resemble in appearance.

Development

The first effective submarines, those of World War I, had hulls that were broadly circular in cross-section, with a deck plate mounted midway. Their heavy battery tanks were mounted beneath this deck, for stability. The ballast tanks were mounted inside the pressure hull. For compactness the ballast tanks were wrapped around the batteries, low down and sharing the flat surfaces of the battery tank. The Kingston valves linking the ballast tanks to the sea could be left open, a practice known as "riding the valves", and the water level in the tanks controlled solely by the vent and blowing air valves. The drawback was that the ballast tanks, open to sea pressure, had a flat surface to the crew compartment and were thus restricted in strength to the bursting strength of this flat plate. In particular this led to accidents where the boat bottomed safely after an accident, but the excess pressure of "blowing out" was sufficient to cause the internal tank wall to fail.

Saddle tank

Saddle tank may refer to:

Tank locomotive

A tank locomotive or tank engine is a steam locomotive that carries its water in one or more on-board water tanks, instead of a more traditional tender. A tank engine may also have a bunker (or oil tank) to hold fuel. There are several different types of tank locomotive, distinguished by the position and style of the water tanks and fuel bunkers. The most common type has tanks mounted either side of the boiler. This type originated about 1840 and quickly became popular for industrial tasks, and later for shunting and shorter distance main line duties. Tank locomotives have advantages and disadvantages compared to traditional tender locomotives.

Origins

The first tank locomotive was the Novelty that ran at the Rainhill Trials in 1829. It was an example of a Well Tank. However, the more common form of Side tank date from the 1840s; one of the first of these was supplied by George England and Co. of New Cross to the contractors building the Newhaven, Sussex branch line for the London Brighton and South Coast Railway in 1848. In spite of the early belief that such locomotives were inherently unsafe, the idea quickly caught on, particularly for industrial use and five manufacturers exhibited designs at The Great Exhibition in 1851. These were E. B. Wilson and Company, William Fairbairn & Sons, George England, Kitson Thompson and Hewitson and William Bridges Adams. By the mid-1850s tank locomotives were to be found performing a variety of main line and industrial roles, particularly those involving shorter journeys or frequent changes in direction.