A lock designed to fit over the steering wheel of an automobile to prevent the wheel from being turned. This (theoretically) renders the car undrivable, as most cars require over three full rotations of the steering wheel to achieve maximum wheel lock. It is impossible to do it with the lock without it getting stuck on your legs, the roof, or the window. It looks something like this:


where , is the lock, and 2 and C are two hooks that go around the inside of your steering wheel. The hook on the end extends, so you can't take it off when it's locked, and conversely very easy to take of when it's open. When fitted over the wheel, it looks like:

                 /\       /\
                /  \     /  \
               |    \   /    |
               |      |      |
                \     |     /

If anyone wants to do better ascii art they're welcome (that's only my second attempt - comments on doing it better are welcome), but I think you've probably seen them before.

So that's the basics of a steering wheel lock, and quite a good idea it is too - buy something relatively inexpensive (under $50 Australian - under $30 US) that make your car undrivable to anyone who doesn't have the key. The problem is that they are notoriously easy to take off without a key if you have some knowledge of locking mechanisms. I've seen people do it, and it can be done in under a minute - see the movie 'Two Hands' (although it's a slight exaggeration). However I've got one, and most people should for a couple of reasons.
  • Visual Deterrent: People see it. Unlike a killswitch, no one's going to break in and try to steal the car if they see a lock and they don't know how to open it. Also, it's easier to steal a car without one than with one. With any luck, the prospective thief will move on to another car.
  • Protection: The road's a dangerous place these days, and road rage is becoming alarmingly common. Thankfully, the locks are made of steel, are quite heavy and if you're lucky they have sharp bits on the end. Mine even has a nice rubber handgrip at the other end. In other words, no one in their right mind would want to be hit with one (not that I'd even dream of it, your honour). A lock and a foam type fire extinguisher make the perfect defence.

Some popular brands are;