How it works
The parts of a padlock on two drawings: the outside with its key, and a ball-locking padlock cut open. Start with the 5 main parts, then the shackle's legs and the locking works.
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The shackle
The U-shaped shackle has two legs. The toe is the short leg, which comes out of the body. The heel is the long leg, which stays in the body when the lock is open; a retaining pin stops it pulling out.
How it locks
Two locking balls sit in notches in the shackle's legs. Turning the key turns the plug in its cylinder, and a cam on the plug lets the balls fall back, so the shackle spring pushes the shackle up.
- Heel and toe locking means the shackle is locked at both legs, as in this drawing, not only at the toe.
Questions and answers
What is the U-shaped part of a padlock called?
The shackle. Its short leg is the toe and its long leg is the heel.
What holds the shackle of a padlock shut?
Locking dogs, which on many padlocks are ball bearings pushed into notches cut into the shackle's legs.
What makes a padlock pop open?
The shackle spring. When the key frees the locking balls, the spring pushes the shackle up into the open position.