How to choose a Padlock: Types And Features : Door Padlock
Quote from Article entitled How to choose a Padlock: Types And Features:
Also it is necessary to distinguish between models with and without levers. In the first case, the spring is controlled by levers, which snap onto the shackle. For a bilateral mechanism a double-bitted key is needed. The without-lever locks use a bolt, which puts pressure on the spring. When the key presses the bolt, it pushes up the shackle. These are the basic principles of operation for some of the above models.
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