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The Locking Mechanism

The Pin Tumbler Mechansim

As mentioned previously, Kasp™ padlocks use a Pin Tumbler locking mechanism. An effective and versatile system that uses pins of varying length to stop the cylinder being turned without the right key.

The picture to the right shows a locked padlock without a key in the cylinder. You can see that the top pins are partially pushed into the cylinder by their springs, which stops the cylinder from being rotated. The locking bars are engaged in the notches in the shackle, holding the shackle closed.

When the correct key is inserted, the gaps between the bottom pins (green) and top pins (red) line up with the edge of the plug, this is known as the 'Shear line'. At this point, the cylinder can be turned. As it turns a mechanism on the top of the cylinder pulls the locking bars out from the shackle and the padlock springs open.


Pin Tumbler mechanisms rely on precision machined components, the last thing you want is dirt getting into the mechanism. If it does, the padlock may become stiff or even seize.


If there is a risk of it happening, it would be sensible to offer a padlock that features protection for the cylinder. The Kasp™ 135 series harsh environment padlock has a waterproof cap that clips over the keyway, keeping muck and grime out.


We recommend lubricating the locking mechanism from time to time using light oil - WD40 or similar is ideal for the job.

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