You know those little chocks you can use to keep your car tire from rolling? They're called wheel chocks, and they could save your life. Wheel chocks are definitely one of those precautionary measures that never catch the spotlight; you only realize you need them when they're not there and your car is running.
 |
| How Wheel Chocks Work |
Wheel chocks may sound pretty boring, but they are actually a major foundation of physical science. They are technically wedges or ramps, which are both different names for the inclined plane. There are all sorts of things that an inclined plane can be used for (like a bike ramp or an axe), but for our purposes, we'll see how an inclined plane serves as a wheel chock.
Basically, all a wheel chock does is prevent a wheel from doing what it does best: rolling. The physical phenomenon of friction (created by the constant exertion of gravity on everything on the planet), keeps the bottom of any wheel firmly pressed against the ground. What a wheel chock does is provide a ramp that the wheel must climb if it is to continue turning.
Both metallic and synthetic materials are often used for wheel chocks. Aluminum chocks are often designed with teeth on the bottom, which bite into the surface below and provide stability. Plastic or rubber wheel chocks provide stability through the friction created between the non-slip material and the ground. Almost all manufactured wheel chocks also have some sort of tread on their face to produce friction between the tire and the chock. In addition, some chocks are designed with a curve that follows the shape of the tire. Others are simple pyramids or may have a lip at the bottom to wedge firmly between the tight spaces where the tire rubber leaves the road.
All of these wheel chocks should do the trick, but there are other requirements you will need to consider when selecting chocks for your vehicle. Because weight and gravity combine to force a wheel down, make sure you have a wheel chock that can handle the weight of your vehicle. Most chock manufacturers specify the weight their chocks can hold, so be sure to check how much your vehicle can hold before you buy.
The type of vehicle and tire you plan to chock also makes a difference in the chock you choose. Heavy off-road tires used on large equipment like earthmovers and grading equipment require a different chock than your family sedan. Check the packaging to see what type of vehicle the chocks you buy were designed for.
Now you've done your homework and purchased the right wheel chocks for you. Read the next page to learn how to use them properly.
Installing Wheel Chocks
 |
| chocks |
Whether you're changing your oil, broken down on the side of the road, or some nasty villain cut your brake line and you managed to stop before crashing headlong into an overpass embankment, wheel chocks can really come in handy. As we've learned, they are an uphill obstacle for your car's tires, and wheels don't naturally move uphill. Plus, a wheel chock uses friction to keep your car from sliding. So it's a good investment to keep in your trunk. But what exactly is the best way to install wheel chocks?
Depending on the slope of the street where your vehicle is parked, wheel chocks should be installed on the side of the wheel that faces downhill. If you are unsure which way your street slopes or if it appears flat, it is 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 left rear tire, for example, you will also want to place another chock behind the right rear tire. For best results, chocks should be installed on the rear wheels as recommended by the Occupational Safety and Hazard Administration (OSHA).
Thanks to our friend gravity, a wheel on an incline will always try to roll down to the bottom of that incline (say, a gentle slope along your street). A wheel chock provides an opposite angle to what a wheel is trying to do by counteracting the slope of your street. Voila! Your car's tires can rest easy knowing they've done everything they were supposed to do: balance.
Wheel chocks are also a challenge for a wheel. If there's anything a wheel doesn't naturally want to do, it's climb. A wheel chock presents this challenge when climbing, and it doesn't matter if the hill presented is two inches or two meters, it will act as a barrier and hold your wheel in place.
OK, so now you know more about wheel chocks than you thought you did. Read the next page to learn how to select the right ones for you.
Read also: How to Test Your Car Alternator for Power
Attaching Wheel Chocks
 |
| chocks |
Wheel chocks are a relatively inexpensive investment in your safety and the safety of others. Anyone who has purchased chocks knows that there are a variety of options available on the market. So which one is right for you?
Wheel chocks are made in different shapes and from different materials. All of them, however, are inclined planes; if used properly, each should get the job done. Since all chocks provide a hill for a wheel to climb if it wants to roll, it doesn't matter if it's two inches or two meters high. However, this lack of difference is only for a perfect wheel, and tires are not perfect wheels. They can change shape. Tires are not rigid, so a tire can bend around a small enough wedge and continue its descent. In the case of selecting a wheel chock for tires, the larger the better. Many chock manufacturers also specify the tire height for which their chocks are designed.
When you need wheel chocks, it may be a matter of fate, such as when you are stuck on the side of the road. In these cases, you won't have much choice about how you park your car, such as how steep the road is. But if you're servicing your car (a situation that always requires chocks) and you have a choice about where to park it, there are a few things to consider.
First, look at the type of ground you are parked on. A smooth surface like pavement or concrete will provide the most friction for the bottom of the wedge to grip. Loose ground like dirt or gravel can allow the chock (and your car) to slip and slide. Dry ground is also important; icy or rain-soaked pavement can also reduce the friction your wheel chock needs to do its job.
Second, try to find a place that is sheltered from the wind or protected by windbreaks like trees or structures. A strong wind can make a car roll, 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 sidewalk that is protected from gusty winds.
When 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 fit snugly and in the center of the tire, never on either side. Follow a similar procedure if you are using wheel chocks on a trailer you are storing (which is always recommended). Keep the trailer attached to the vehicle towing it. Place the vehicle in park and set the emergency brake. Securely install wheel chocks on both sides of both trailer wheels. You can now detach the trailer from your vehicle.
Taking just a moment of effort to install wheel chocks can prevent an accident that could injure or even kill you or others. And with most wheel chocks priced between $10 and $30.
The Importance of a Good Wheel Chock