Each year in the United States, semi-trailer trucks travel roughly 140 billion miles of crisscrossing highways across the country to transport 68% of the United States’ goods and merchandise. With many miles to log and important, often heavy cargo to tow, it’s crucial to equip these trailer trucks with reliable brakes. The brakes beneath an 18-wheeler (or another big trailer like a caravan or RV) rely on magnets to stop all that weight and momentum. But how do they manage to do it? How Magnets Protect Our Goods Let’s take a look at these big semi-trailer trucks. Typically, they implement air brakes, but air brakes aren’t powerful enough to stop the truck and trailer, which together can weigh more than 50,000 pounds. That’s where electromagnets come in. Wires from the truck extend back to the wheels, allowing electricity to travel from the front to back. When the driver brakes, the truck sends a current through the wires back to an electromagnet near the outer surface of the magnetic armature, a sort of drum connected to the wheel. The magnet armature turns with the wheel and rushes right by the electromagnet. However, when a current runs through the electromagnet (in other words, the driver brakes), its magnetic pull causes it to grab onto the ferromagnetic armature.  When the brake grabs onto the armature, the armature’s momentum drags it along for the ride. While it’s moving, the electromagnet pulls on a nearby brake shoe, which presses against the outer edge of the drum. This pressure creates a level of friction the brake shoes are built to withstand, and this, in turn, stops the drum from moving. Since the drum and wheels are connected, the wheels also stop turning. The end result? The trailer comes to a full stop in time to avoid a collision.  When the driver releases the brake, the electric current that was flowing into the electromagnet disappears. This causes the electromagnet to release the magnet armature, allowing the wheel to spin freely once more. The trailer can now move freely until the driver hits the brakes again. Apex Magnets: Here to Help With Your Most Demanding Jobs Need powerful, industrial-strength magnets? Then you need Apex Magnets. With an extensive product line that includes powerful nickel-coated neodymium and durable plastic-coated magnets, you’ll find everything you need to run your business smoothly.  Contract Apex Magnets with any questions you have about our products or magnets in general —our associates are standing by.