ABSTRACT
Figure 18.1: The types of lock used on dwelling houses are few and vary between locks, latches and combinations of these two. They may be mortice locks morticed into the door-edge, or various types of rim lock fixed on the inside face-edge of the door. The actual latch part of a lock is usually spring-loaded, quadrant shaped, or has a round-edged roller bolt, which holds the door closed (latches it) without locking it – unless it is a type of cylinder night latch, which requires a
and turning a key. The concealed part of the bolt, as illustrated, has a small metal post protruding from it, which must be moved through an open gate cut in the middle area of a specified number of sprung levers. This happens when the key lifts the levers, gains access to the edge of the bolt and moves it. The more levers a lock has, the greater the security. The quadrant-shaped latch is usually reversible to enable the hand of the lock to be changed from left to right, or vice versa.
