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Inspecting and Replacing Brake Lines
By Mike Bumbeck/
Printable version
Degree of DifficultyModerate
Estimated Time120 minutes
120 minutes
Put a Stop to a Sudden Loss of Brakes
Automotive mechanical mishaps can range from a minor inconvenience to a major disaster. Leave the lights on? A dead battery is doable, just call roadside assistance or walk over to the nearest super-duper hyper mega mart. Pick up a new battery and an adjustable wrench. Install the new battery, bring back the old one and you're off. Easy. Forget to put gas in the tank? That's not so bad either. You might even have a laugh about it when you finally get home. These things happen despite even the best efforts at prevention.
No Laughing Matter
Of all the mechanical failures that can happen while driving, sudden brake loss is on the top of the “bad things” list. All laughs and clowning around aside, there is nothing funny about neglecting your braking system. While many failsafe and redundant safety features such as dual reservoir master cylinders and low brake fluid warning level lights have been built into braking systems since the olden days of motoring, a sudden loss of hydraulic pressure in a brake system will amount to an almost instantaneous total loss of braking. One thing that will cause this sudden failure to occur is a ruptured or damaged hydraulic brake hose.

Binding Agreement
Automobile brakes work by utilizing hydraulic pressure. A liquid, such as brake fluid, cannot be compressed. Try it. Before you open that plastic bottle of water to slake a powerful thirst, give the bottle and the water inside a good squeeze. After you empty it, thirst slaked, put the cap on and try squeezing it again. See? Air can be compressed, liquid generally cannot. This is why it is important to bleed the brakes anytime air is allowed into the system. When you press on the brake pedal, a piston in the master cylinder attempts to compress the brake fluid in the system. Since fluid cannot be compressed, it is pushed through the lines.

At the other end of the lines full of brake fluid are more pistons. These pistons live in the calipers and wheel cylinders. The brake fluid pushes on these pistons, which makes them move. On the other side of the pistons are the brake pads or shoes. The caliper or wheel cylinder pistons push out on the brake pads or shoes. The material of the pads or shoes makes contact with the metal brake disc or drum surfaces, and friction causes the vehicle to slow down. While there are volumes of other hydraulic principles at work to give you the Superman-like power in one foot to slow a vehicle weighing thousands of pounds down to stop, brake fluid is at the heart of the system. Without it the brakes will have no power.
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