An internal door latch works by using the rotation of a handle or knob to retract a latchbolt, allowing the door to open and then spring back into place to hold the door shut. Here's a breakdown of the process:
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Handle or Knob Activation: When you turn a door handle or knob, you are rotating a component called a spindle. Spindles are commonly 8mm in size for handles and knobs, but can also be 5mm, particularly when used with bathroom turn and release mechanisms.
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Spindle Rotation: The rotating spindle is connected to the internal latch mechanism.
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Latchbolt Retraction: The rotation of the spindle forces the latchbolt (also known as the latch tongue) to retract into the door. This is the small, usually angled piece of metal that protrudes from the edge of the door and engages with the strike plate on the door frame.
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Door Opening: With the latchbolt retracted, the door is free to swing open.
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Spring Mechanism: The latch mechanism contains a spring. When you release the handle or knob, the spring forces the latchbolt back out of the door and into the strike plate on the door frame.
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Door Closure: Once the latchbolt is fully extended into the strike plate, it keeps the door closed until the handle or knob is activated again.
In essence, the latch mechanism is a simple spring-loaded system that allows you to easily open and close a door, and keeps it closed when desired.
