The ‘key’ of ‘utility and control-cabinet key’ refers to the main structure of the tool including hub, legs and heads. Most models consist of just one key but occasionally two keys are supplied together, attached by a magnet and chain.
Heads
The heads are the functional parts of the utility and control-cabinet key. One key can have up to twelve heads, which vary in shape and size.
Socket head
A socket, or ‘female,’ head is usually cylindrical on the exterior with a particular shape cut into the interior. Common interior shapes include cubes and triangular prisms.
A socket with a cube-shaped interior is called a ‘square socket’ and a socket with a triangular prism-shaped interior is called a ‘triangle socket.’
A socket head of a particular shape fits onto the matching pin or ‘peg’ (shaped piece of metal that sticks out) of a lock or valve.
Stepped pin head
Pin, ‘peg’ or ‘male’ heads are the inverse (opposite) of socket heads. They are usually in the shape of a cube or triangular prism. The shape fits into a lock or valve that has a socket head. As with socket heads, a pin that is a cube shape is called a ‘square pin’ and so on.
A ‘stepped’ pin head is a pin head that can be used on more than one size of lock. The different sizes are stacked on top of one another with the largest size at the bottom, nearest the hub, and the smallest size at the tip of the head, furthest from the hub.
Stepped pin heads are more common than single pin heads because they save space on the utility and control-cabinet key, maximising the number of profiles (key shapes) it can have. Socket heads are not stepped, so each size takes up a head.
Some utility and control-cabinet key models have a separate stepped pin head attachment which fits into a socket on the main body of the tool. The attachment is held in place by a magnet.
Profiles
The profile is the shape, size and type of the utility and control-cabinet key head. Most heads have just one profile (e.g. 5mm square socket)…
…but stepped pin heads have multiple profiles.
Hub
The hub is the centre of the tool, where the parts join together.
On some designs, the hub carries a socket head as well. It is usually a 5mm square socket (a head with a cube cut into the interior) which can be used on standard radiator bleed screws.
Some models containing plastic parts may not have such a defined hub due to their variation in shape.
Keys with a single profile do not have a hub at all: they have a handle instead.
Legs
A leg joins a head to the hub or the handle (if it is a single profile key).
The length of the leg defines the reach of the key (referred to as ‘execution’ length) and also makes the tool easier to use by separating the heads from each other and providing a handle to turn the other heads more easily.
On keys with more than one profile, there are between two and four legs and they all stick out around the hub like hands on a clock. Two-legged keys only occur as keys with plastic frames (see below) and retain a hub at the centre of the tool where the frame parts meet.
The multiple legs sticking out from the hub is what gives the tool the name ‘spider key.’
The legs on keys with plastic frames are slightly different to those on solid metal keys. Instead of a solid bar, they form a frame that holds the metal head away from the hub, or centre, of the key.
Loop
The loop allows keys to be joined together, attached to a belt or to accessories using a chain or rope. Some models do not have a loop.