MEJORAS EN APARATOS TELEFONICOS.

摘要

The alarm bell assembly is mounted on a plastics base plate by a post which fits into a hole in the plate and is rotated to lock the assembly in position. The post has two radially projecting arms which locate under ratchet-type slopes beneath the plate as the post is rotated in one direction. Rotating the post in the opposite direction causes the arms to press against ratchet springs cut out of the plate with sprung flaps. The alarm bell assembly can be mounted on the base manually be inexperienced personnel and can be easily replaced.