The fundamental function of a rock crusher is to smash bigger rock objects and crush them to the desired size. The process starts by first passing bigger rock objects into the crusher. There are various levels of crushing operations that are carried out. Sometimes crushing is accomplished in a single crushing cycle. While sometimes the process of crushing needs to be carried out until the rock objects are converted into dust particles. Not all kind of engineering processes need the same level of crushing. So, a rock crusher is available to suite every need. Generally the process begins with crushing big rock objects with a primary rock crusher; later those crushed rocks are further crushed with a secondary rock crusher. These crushed objects may be further crushed with a tertiary or quaternary rock crusher if the need arises. There is a certain limit to the maximum size of the rock that can be crushed in a particular rock crusher. The actual process of crushing begins with unloading the rock material onto the rock crusher's hopper. There are various means through which this is done; like trucks, excavators or loading/unloading machines. Once the rock is put onto the hopper, the rock is taken into the crusher. The speed at which the rock is moved into the crusher is regulated by its conveyor or vibrating grid. During this process, smaller rocks (which don't need crushing) are filtered aside.