Three-throw Switch

In a three-throw arrangement, two turnouts take off from the same point of a main line track. A three-throw switch can have contrary flexure or similar flexure, as shown in Figs 15.4 and 15.5, respectively. Three-throw switches are used in congested goods yards and at entry points to locomotive yards, where there is a great limitation of space.

Three-throw switch (contrary flexure)
Fig. 15.4 Three-throw switch (contrary flexure)

A three-throw switch has two switches and each switch has two tongue rails placed side by side. There is a combined heel block for both the tongue rails of the switch. The switches can be operated in such a way that movement is possible in

three different directions, i.e., straight, to the right, and to the left. Three-throw switches are obsolete now as they may prove to be hazardous, particularly at higher speeds, because the use of double switches may lead to derailments.

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