Over 1 million cars are scrapped every year, but this is not the end of their life. Cars contain a wide variety of valuable metals that can be recycled and reused. Powerful car crushers compact the scrap steel, making it much easier to transport for the recycling process.
Modern car crushers tend to employ hydraulics to compact the scrap metal – using a powerful motor and large hydraulic cylinders. Pressurized fluid generates huge crushing forces behind the plates. The body of the machine must be able to withstand the extreme forces required to flatten a steel chassis, so they are constructed from even tougher materials – most often hardened steel.
As steel is magnetic, cars can be loaded onto the crusher using a crane and a large magnet. However, other heavy machinery such as forklift trucks and cranes with lifting claws (see below) are also called upon for the task.
Once the cars have been compacted, they are shipped to a shredder with the resulting metal scraps sorted according to type before being melted down for reuse. Crushers typically contain a reservoir to collect motor oil that leaks from the vehicles during crushing, and even this can be reused.
Hydraulics work on a simple principle: transferring force from one place to another using an incompressible fluid – often oil. A pump supplies oil at high pressure, which is fed to hydraulic cylinders and pistons. The fluid is not compressed, allowing most of the force to be transferred to the crushing plates.
By altering the piston and cylinder size, the force generated by the pump can be massively multiplied, allowing relatively small amounts of fluid to do huge amounts of work – like scrunching up a car as easily as a packet of crisps.