A puller is a tool for separating parts from one another. The term is very commonly used this way in an automotive context, as there are many parts of an automobile which must be removed with a specialized tool. Most gears, for example, must be removed with a gear puller, and there is even a special steering wheel puller. Both of these devices (and many other pullers besides) use a threaded shaft or bolt which is turned to push on the end of the shaft, while arms grip the circumference of the part or some other facet of its design intended for the purpose.