Interlocking machine & interlocking plant

Interlocking machine-the principal of interlocking requires that before a signal can be cleared for the movement of a train ,all switches ,derails & frog points,over which the signal governs train movement , shall be in proper position & locked. to secure such protection for train movement it is desirable to concentrate the control of the various switches and signals at one point. the mechanism in which this concentration of control is secured is called an interlocking machine. the machine consists of small hand throws levers, compactly located in a frame & arranged for the operation of circuit controllers, but restricted in their movement by both mechanical locking and electrical locks. Interlocking plant-a group of levers concentrated at a central point for operating certain switches and signals , and so arranged as to interlock such levers and make it impossible to give clear signals for conflicting routes. the advantages derived therefrom are safety , facility of operation and saving in cost of manual lobour employed.