Fig. 70.—Tumbler Switch. details

“The weak points of this switch would appear to be: –

The small handle, which, it will be noticed, is not easy to catch hold of;

The possibility of the spring which throws the contact bar “Off” losing its tension, and therefore failing to release the latter from the grip of the fixed contact pieces;

And the fact that any wear of these portions of the contact pieces which face each other is sure to lead to loose contact and its attendant sparking, it being also certain that such wear will take place.

On the other hand, the switch fulfuls many of the requirements of a perfect switch. The connection between the moving and fixed contact pieces remains good, until one of them is worn, or one of the fixed pieces is pushed on one side. The arrangement provides that great desideratum, a rubbing contact, thereby ensuring tht the dirt made by the spark on turning the switch off shall be removed next time the switch is turned on. The switch is also neat and compact, and the “pull-off” is fairly quick, so long as the spring retains its tension.” (p. 176)