Difference between revisions of "Change-over Switch"

Revision as of 14:31, 15 August 2009

A Change-over Switch (usually C.O.S. in British sources) is a rotary electrical switch, often a large cylindrical one that multiplexes a number of inputs to any one of a variety of outputs.

These were often found within a Transmitting Station, though smaller ones were also found in gun turrets and similar stations serviced by a large number of electrical connections.

Applications

A typical purpose for a C.O.S. would be to manage in one nexus, the many parallel connections that should sensibly be established or altered when a ship with multiple directors and/or T.S.s wished to switch which director or T.S. was to be used.

Generally, all firing, elevation, slewing and training data cables from directors to turrets would come through the C.O.S., and each of its 3-5 rotary stop positions would establish different patterns of connection to permit some flexibility as to which turret is connected to which director. The parallel path of the several connections that need to be made for this to be done successfully is intrinsically managed by the inner rotating column within the C.O.S., and this reduces the possibility of having a switch out of place (as there is only a single switch instead of many).

As an example, imagine a ship with a a forward and an aft director that was firing its guns using the forward director. A new target emerges suddenly, and it is decided that the aft group of guns should engage this target, using the aft director. Here is how it would be done:

1. A quick check fire would be established and the forward director would freeze in place.
2. The aft director and aft group would slew to a pre-arranged line-up bearing and elevation as an operator within the T.S. threw the C.O.S. from "all guns on forward director" to "fwd guns on fwd, aft guns on aft". This action would disconnect the elevation, slewing and training connections that had previously bound the aft turrets to the forward director, and establish them with the aft director.
3. A quick verbal check would be made to ensure that the receivers in the forward guns had not jumped due to a transient as the switch was thrown. If it succeeded, the forward guns could immediately proceed under control of the forward director.
4. The aft director and guns would undergo a lining up of pointers to synchronize themselves. Once complete, they would be able to fire upon their new target.

This is a general description. The routing of the wiring within any ship and its C.O.S.(s) bears study before one can grasp how flexible its fire control apparatus and staff could be, and how prone it might be to degraded accuracy when changing modes in this manner. For instance, with a single Dreyer table, who would supply the range and deflection information for the new aft gunnery group? How would the range and deflection data get to the sights? Did they also get handled by the C.O.S.? Did orders signals get routed by the C.O.S.? Telephones? Spotting?

Footnotes

Bibliography