Latch for the headrest of a dentist's chair - has sprung lever released by pushing headrest forwards

摘要

The latch is a sprung lever attached to teh head rest by pivots. A curved member of the fixed frame of the chair passes through a hole in the lever. When the head rest is moved round the horizontal axle that supports it, the lever moves along the fixed member. The spring turns the lever on its pivots until the edges of the hole in the lever jam against the curved member, and thus the head rest is held. Releasing the spring tension - which can be done by pushing the head rest forwards - allows the head rest to be adjusted to a new position.