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How Wheel Chocks Work

Installing Wheel Chocks
Always place wheel chocks against the direction of the grade.
Always place wheel chocks against the direction of the grade.

Whether you're changing your oil, broken down on the side of the road or some nefarious villain has cut your brake line and you managed to come to a halt before crashing headlong into an overpass embankment, wheel chocks can really come in handy. As we've learned, they provide an uphill impediment to your car's tires, and wheels don't travel naturally uphill. What's more, a wheel chock uses friction to keep your car from sliding. So they're an all-around good investment to keep in your trunk. But exactly what's the best way to install wheel chocks?

Depending on the incline of the street where your vehicle is parked, wheel chocks should be installed on the side of the wheel that faces the downward slope. If you can't figure out which way your street is sloping, or if it seems flat, it's recommended that you chock both sides of the wheel. Always use pairs of chocks in tandem along the rear tires. If you place a chock behind the rear left tire, for example, you'll want to place another chock behind the rear right tire as well. For best results, chocks should be installed on the rear wheels, as recommended by the Occupational Safety and Hazard Administration (OSHA).

When you need wheel chocks can be a matter of fate, such as when you're stranded on the side of the road. In these cases, you won't have much choice about the conditions of where your car is parked, like the gradient of the road. But if you're carrying out maintenance on your car (a situation that always calls for chocks) and you have a choice of where to park it, there're some factors you should consider.

First, look at the type of ground on which you're parked. A smooth surface like pavement or concrete will provide the most friction for the bottom of the chock to grip. Loose terrain like dirt or gravel can allow the chock (and your car) to slip and skid. Dry ground is also important; ice or rain-soaked pavement can also reduce the friction your wheel chock needs to do its job.

Second, try to find a place away from the wind or protected by windbreaks like trees or structures. A strong wind can roll a car, and you don't want that. The ideal place to park your car when using wheel chocks is on a flat, dry, smooth strip of pavement away from wind gusts.

When you're using wheel chocks, be sure to park your car and engage your emergency brake before installing the chocks. Place the chocks against the tire and make sure they're snug and in the center of the tire, never to one side or the other. Follow a similar procedure if you're using wheel chocks on a trailer you're storing (which is always recommended). Keep the trailer attached to the vehicle that's towing it. Place the vehicle in park and engage the emergency brake. Install wheel chocks on both sides of both wheels of the trailer securely. Now you can detach the trailer from your vehicle.

Taking just a moment of effort to install wheel chocks can prevent an accident that could harm or even kill you or others. And with most wheel chocks priced in the $10 to $30 range, how can you afford not to have a pair?

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