How Car Crushers Work

For every beginning there's an end. Every shiny new car on the showroom floor will one day end up in a junkyard, its value no greater than the weight of the metal used to build it. North American auto plants built 15.8 million cars in 2005 -- all of which have to end up somewhere [Source: Business Week]. One of the most important stops an old car reaches at the end of the line is the crusher -- a massive machine whose only purpose is to compress a car into a tiny cube or flattened slab.

In this article we'll learn what a car crusher is, how they crush and why take the time to turn a car into a brick of steel.


A car crusher is a piece of machinery used to compress the metal remains of a junked car after it has been stripped of all useful parts. Compressing them takes up less space when stored, or when transported via truck or train to a recycling facility. A crusher is just one step of the auto-recycling process. They can also be used to compact other forms of metal waste, such as old appliances or even large machines like combines.

­ A car crusher
­ A car crusher

Crushers can be portable or stationary. Older machines tend to be stationary -- once they're set up in a scrap yard, they stay there. Today, most crushers are portable. They are built mounted to a standard-size truck trailer, and can be towed to various locations, set up, used to crush some things, then moved somewhere else. This helps cut costs for auto salvage yards - instead of buying an expensive machine, they can split the cost with other yards or rent time on a crusher that comes by once a week.

How Does a Crusher Crush?

Almost all modern car crushers use a hydraulic press to crush the cars. A large motor powers a pump that pushes hydraulic fluid to drive large cylinders. Using principles of force-multiplication, a hydraulic system can generate over 2,000 psi and impart more than 150 tons of crushing force onto a pile of scrap cars. For more details on hydraulic systems, read How Hydraulics Work.

  • bed where all the cars are loaded.
  • A crushing plate rises to make room for the cars, and then drops to apply the crushing power.
  • The engine, pump, valves, tubing and other parts of the hydraulic system.
  • Guideposts that align the crushing plate and make sure the crushing force is applied evenly.

In a "bale" crusher, another set of pistons pushes another crushing plate in a lateral direction. Once the car has been crushed flat, it's crushed sideways, forming a "hay bale" of compacted car. Some baler crushers use specially shaped "claws" that fold the cars into bales or square logs. You can view this diagram showing how this works.


In addition, an oil reclamation system sits below the crushing bed. When motor oil and other fluids drain from the crushed car, they run down into this system where they are collected and stored for later recycling.

Other Crushers

A car crusher in action
A car crusher in action

There are other kinds of crushers, such as hammer crushers, which use huge plates or protrusions on spinning wheels to smash whatever is being crushed into bits. However, these are used most often in industries that are crushing rocks. Auto recyclers might use them to render scrap metal into smaller pieces, but this is rarely the first step in the recycling process for a car.

Some stationary crushers use a large electromagnet on a lifting arm to "grab" metal cars and drop them into the crusher. Shredders also use magnets to separate steel parts from non-ferrous materials.


Car crushers must be made with thick, hardened steel. The material has to be tougher than whatever it is they're crushing. This toughness is the reason that some of the original crushers made in the 1970s are still operational today.

To buy your own car crusher (great entertainment at backyard cookouts), plan on shelling out at least $30,000 for an older, used model. A brand new crusher will cost between $120,000 and $150,000.

Operating a Car Crusher

The basic function of car crushers hasn't changed much since they were invented in the 1970s. Improvements in car crusher design focus on two areas: ease of use, and set-up and crushing speed. Older crushers needed more than one operator, and setting up and tearing down a portable crusher could take a lot of time. New crushers have automatic push-button set-up and can be easily run by a single operator. Faster crushers mean more cars crushed per minute, and the more efficient a crushing operation is, the more money the crusher's owner can make.

Once a car reaches the junkyard, it goes through several steps before finally being shredded to scrap metal.


  1. The car is stripped of all working parts. For example, a car may have a cracked engine block, but the transmission is fine. Salvage crews pull out the working parts for resale. A huge number of parts can be resold - body panels, carburetors, wheels and tires, suspension parts and entire engines can be refurbished and sold to do-it-yourselfers.
  2. Hazardous materials are removed. The battery is pulled out and chemicals in the air-conditioning system are drained. The gas tank is removed and drained (and resold if it's in good condition).
  3. The car is left in the junkyard until it's time to be crushed. It could be there for a few hours or even a few months, depending on how big the backlog of cars that need to be crushed is.
  4. The operator drives the crusher to the junkyard and sets it up (if it's a portable crusher).
  5. Cars are loaded onto the crushing bed with a forklift, an excavator with a huge claw on the end or a magnet. Some crushers have a crane with a lifting claw or magnet built into the crusher itself.
  6. The operator activates the hydraulics, crushing the cars as flat as possible. The crushed cars will take up less than half of the space they originally required, and in some cases as little as ten percent. How flat they get depends on the crusher and what kinds of cars are being crushed. Baler crushers can reduce a car to a brick of crushed metal that's about three and a half feet high, two feet wide and three to five feet long [Source: Al-jon].
  7. There may be an additional storage period before the cars are shipped to a shredder.
  8. The cars are loaded onto trucks or a train and shipped to a recycler where they will be shredded down to chunks of scrap metal. Often, the stripping and salvaging steps above are skipped - whole cars, tires and all, are fed into the crusher, and then shipped to the shredder where the shredded chunks themselves are sorted.

Granutech's Big MAC portable crusher needs about 45 seconds per car, and can crush four or five cars at a time. Overbuilt's Model 10 crusher is built with a higher clearance on the bed, allowing trucks and buses to be crushed, or six cars at one time. A special hydraulic system that allows rapid transfer of hydraulic fluid increases overall crushing speed [Source: American Recycler].

Why Crush Cars?

Parts for resale after being stripped from a car.
Parts for resale after being stripped from a car.
Photo courtesy of Cooksville Auto Recycling

Why do we need to crush cars? The most obvious reason is so they take up less space. But why are we scrapping, shredding and junking cars to begin with? Recycling cars is a lucrative business, and it makes environmental sense.

The sale of reusable salvage from old cars is only a small piece of the auto recycling pie. About 65 percent of a junked car is made from steel (the rest is made from other metals plus glass, rubber and upholstery). The price for scrap steel and iron, though volatile, often hovers around $250 per ton. Expanding economies in Asia have lead to greater demand for scrap steel, bolstering the market worldwide. With 14 million tons of steel from cars being scrapped each year contributing to an industry-wide total of 76 million tons of recycled steel and iron, it's easy to see that auto recycling is a multibillion dollar industry [Source: ISRI].


Recycling metal uses about 74 percent less energy than making new steel, according to the Environmental Protection Agency. Recycled steel is cheaper as well, since new ore doesn't have to be mined to produce it. All steel produced today has at least 25 percent recycled steel in it, and some products are made entirely from recycled steel. So in addition to the economic and environmental benefits, recycling cars is a vital link in the world's industrial infrastructure.

Lots More Information

Related HowStuffWorks Articles

More Great Links

  • Al-Jon. "Al-Jon 580 CL Car Logger."
  • BBC News. "Man 'helped killer after seeing murder'."
  • BusinessWeek. "The Good News About America's Auto Industry." Feb. 13, 2006.
  • Environmental Protection Agency. "Steel."
  • Henricks, Mark. "Equipment Spotlight: Auto Crushers." American Recycler, Nov. 2005.
  • Institute of Scrap Recycling Industries, Inc. "Industry Overview." 2FTaggedPageDisplay.cfm&TPLID=101&ContentID=6102#17068151686768307147
  • Williams, Fred O. "Firm's machine chews up 6 cars a minute." Buffalo News, May 28, 2007.