How Padlocks Work

的Basics of Padlocks

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Learn about the standard padlock to understand the main parts, how they work and also how to bypass the mechanical security features to pick the lock.

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的Padlock

Padlocks

Padlocks come in many shapes colours and sizes. They have been around for hundreds of years, ranging in complexity of design by different people and civilisations depending on the technology and manufacturing processes they had available. With the industrial revolution came the mass-produced padlock which eventually settled on a pin tumbler design. Called so because inside are some pins and a barrel which rotates or tumbles over.

Pin Tumbler Design

的se are strong mechanical locks which are easy to mass produce and we find them used for everything from keeping our bikes where we left them to symbolising the everlasting love between two people on a bridge, and then throwing the key away to ensure it can’t be undone. But these types of locks, especially the cheap ones, can be unlocked without a key if you know the correct method and once we understand how the lock works we’ll learn how to pick the lock.

挂锁如何工作

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When we look at a padlock the most noticeable feature is the U-shaped shackle at the top. In the unlocked position, one end of the shackle pops out of the main body allowing this component to rotate freely. On the inside surface of the shackle we will find two notches. These form part of the lock mechanism and we’ll see that part shortly.

Notches

To lock the padlock we simply align the end of the shackle with the hole in the lock body and push these together. You’ll feel the internal locking mechanism engage and click into place, the shackle will now be unable to leave the body of the lock. To unlock the padlock we need to insert the correct key into the key hole at the bottom of the lock body, and rotate the key until it releases the shackle.

Locking a Padlock

When we look inside the padlock body, we can see the locking mechanism.

Inside Padlock

的first part is the plug. The key will slide into the plug and follow the groves to ensure a smooth transition.

Plug

当关键是转身的时候,塞将旋转。的plug has a number of holes in the top, within each hole there is a small metal cylinder known as a key pin. Each key pin is a different height, and this will correspond to the profile of the key.

钥匙销

Within the housing of the lock we find a number of chambers which align with the holes on the plug.

Chambers

在每个腔室内,我们找到一个推动另一个引脚的弹簧,称为驱动器引脚。

的spring pushes the driver pin into the corresponding hole of the plug until it touches the key pin. This also ensures the driver pin remains in contact with the key pin even when the padlock is rotated upside down.

Pin

插头和锁定壳体之间的交叉被称为剪切线。没有键插入钥匙,驱动器销位于壳体室中的部分方式和插头内的部分方式。这意味着插头无法旋转。

Shear Line

当键插入锁定时,键引脚将遵循键的配置文件并向上移动,直到键完全插入。一旦完全插入,如果使用了正确的键,则每个键引脚的顶部将与剪切线对齐。驾驶员销将被推动,现在将在封口内完全坐在外壳内。这意味着插头现在能够旋转。如果插入了错误的键,则引脚不会对齐,插头将无法旋转。

6 Chambers

Notice this lock has 6 spring loaded chambers. Only 5 of these are used by the key to form part of the lock. But the 6thdriver pin sits within a deep groove and is not used by the key. Instead, this pin is preventing the plug from being pulled out of the lock body and it does that because it is always engaged into the groove in both the locked and unlocked position.

6th Pin

因此,一旦我们拥有正确的钥匙,我们可以旋转插头,我们现在需要一种方法来释放卸扣,而确保在没有钥匙的情况下无法删除。

Cam

在插头的末尾,我们有一个凸轮。这只是一块金属延伸,延伸到插头的主体,但它具有这种形状,允许它像雪花一样行动。

Latches

围绕凸轮是闩锁,在任何一侧放置。闩锁的最外端是成角度的并且将适合于钩钩的凹口中。弹簧坐在锁内,将推动每个闩锁,向外迫使它,使成角度的边缘被迫进入凹口。这种闩锁和缺口的互锁可以防止束拔出。

泉水

每个闩锁的最内端具有小臂,该臂延伸,靠在凸轮的平边上。一个闩锁靠在顶部,另一个闩锁靠在底部。当凸轮旋转其形状时使闩锁臂向向内拉入春天,从钩住凹槽上的凹口上拆下它们。

Arm

的shackle can be lifted out at this point, but to make it easier to use, a spring is placed under the longest end of the shackle, within the lock main body. This will push the shackle out making it easier to use, but also letting us visually tell if the lock is unlocked or locked.

Spring Under Longest End of Shackle

So to recap on the operation of a padlock.

的key is inserted into the plug. The different sized key pins rest inside a number of holes inside the plug and will move up and down to follow the profile of the key. If the correct key is inserted then the top of the key pins will align with the top of the plug. This pushes the driver pins out of the plug holes and into their respective chamber. The springs ensure the driver pins will be forced into the holes if the wrong key, or if no key, is inserted.

通过清除所有销钉,键可以旋转插头。在插头的末端是一个也用插头旋转的凸轮。这与两个闩锁的臂连接。闩锁被弹簧向外推动,这将臂推靠在凸轮上,但也将闩锁推入载体上的凹口,防止锁定在没有钥匙的情况下从开口打开。使用正确的钥匙插入插头可以自由旋转,这旋转凸轮,该凸轮向内拉动闩锁,释放卸扣。载物室内的弹簧推动臂向外释放锁定。

Pick a Lock

So now that you understand how the padlock works, we can understand how to bypass the security mechanisms. The most import part is that the internal pins align with the shear line. So for that we need a lock picking kit.

Clear Padlock

If you want to clearly understand the mechanism of how locks work as well as how to pick a lock, then you can buy one of these transparent locks, these clearly show you the pins of each chamber as well as how the components work together as you lock and unlock it. You can buy itHERE.

If we look through the key hole we can see the key pins inside the plug and the driver pins pushing down against these.

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From the side we see the spring loaded latches engaged with the notches in the shackle, which prevent the lock from unlocking without the key. The shackle spring is also fully compressed.

Side View

As we insert the key we can see the pins move up and down, following the profile of the key. With the key fully inserted we have all 6 key pins aligned with the shear line, so with a little twist we disengage the lock mechanism. Notice as we continue to rotate the key, we can see the cam on the end of the plug moving the arms of the latches. Which pulls the them inwards, away from the shackle notches and this disengages the lock.

Cam

With the plug rotated in the unlocked position we can see the key pins inside the plug and the driver pins in their spring loaded chambers.

钥匙销

的shackle is pushed out by the internal spring. A groove is cut into the shackle arm and a bar within the locks body passes through this space preventing the shackle from fully leaving.

Groove Cut

So, to unlock the device we need to move the pins to the shear line and also rotate the plug.

扭矩扳手

To do that we inset the torque wrench into the lock and apply a rotational force. Then using a hook we nudge each keypin until it lifts the corresponding driver pin to the shear line and as we complete the set of pins we will feel the lock mechanism disengage and the shackle pops out. Notice only 5 of the 6 spring loaded chambers needs to be nudged, the last chamber doesn’t move up and down with the key and we don’t need to nudge this because it is simply there to prevent the plug from being pulled out of the lock body.

Picking Lock

We can also pick the lock a lot faster by again applying a rotational force to the plug and then fully inserting the hook and quickly scraping across the pins to catch them at the shear line to unlock the device.

Faster Picking

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