Understanding the parts of a safe lock
THE COMBINATION DIAL
The visible part of a combination lock is a rotating circular dial. This is also recognized because it has numbers that are around the dial, starting at 0 at the top and increasing to the right as the dial is turned in that direction. The dial is essential to be able to open the safe, all this hitting the correct combination.
It is the part that joins the combination dial with a cylinder, this when turning the dial makes the spindle turn, this and other parts are internal complementary and are not visible even if the safe door is open.
This circular object located at the end of the spindle to the opposite side of the combination dial, is screwed into the spindle and rotates with it. A small drag pin extends from the cam, and serves to hold the wheels and keep them rotating.
THE WHEELS OF THE SAFE
Known as drums, they are found surrounding the spindle although they are not attached to it. The drag pin has to hold them in order to turn. There are drums or wheels based on the number of combinations, which are normally from 2 to 6. This means that if we have a combination of 4 numbers (4-25-15-40), then we will have 4 wheels or drums.
Without knowing the combination you can know how many wheels there are. Knowing the wheels there are, it is easier to open the safe. Each wheel next to or against the lug pin has small tabs on it known as the “flywheel.”
It is the cam that makes contact with the wheels to keep them rotating.
The fence is a small rod that rests on top of the wheels, and still does not prevent them from turning. The fence connects to a lever mechanism which is responsible for keeping the box closed. As long as the fence remains in place, the box will remain locked.
Older texts referred to as “brake”, “lock”, or “lock”, misused today to refer to an object that supports or blocks another.
WHEEL NOTCH SET
Known as grooves, each wheel has a notch at a point along its circumference. By turning the wheel so that the notch is at the top, the fence snaps into the notches. The lever moves and the door mechanism is unlocked.
You will notice because there is a wheel for each combination number. When you select the first number, the first wheel will turn into a position with its notch directly below the fence. It then reverses the direction of rotation to disengage with that wheel and turns the next to its correct position.
The cam has a notch that will “click” each time the notch slides past the lever. The notch in the cam catches the bolt physically blocking the gate and pulling it out of the way, this occurs every time the fence falls and releases the locking mechanism.