 Some mechanical frames were combined with a set of electric levers or switches to more efficiently work electrically powered signals or other non-mechanically operated devices.Typically the switch points would be left under mechanical operation as the other devices used comparatively little electrical power and could be run off of batteries or a low capacity railroad-operated power system.A power operated interlocking frame uses some form of power assist to operate switches, signals and other interlocking appliances in the field.