Street Survival - Advanced Defensive Driving

DEFENSIVE > CONTROLS > BRAKES

Brakes

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See handy points on the use of a vehicle's brakes below:

Questions:

Thinking Distance:

  • This is the time taken to respond to a hazard.

  • 2 Second Rule. Get into the habit of keeping a 2 second distance between yourself and the vehicle ahead. See video for a practical tip on how to do so.

Stopping Distance:

  • Speed - The accompanying chart shows that every incremental unit of speed increase, results in an exponential increase in distance to stop.

  • Gross weight (including load) is directly proportional to the stopping distance.

  • Surface traction.

  • Leave enough space to stop at a distance behind an object to allow enough room to pull out from behind that object.


Defensive Controls Brakes
Defensive Controls Brakes

? What is cadence braking?

Cadence braking, also known as pumping the brakes, is a technique used when a vehicle equipped with conventional braking systems (non-ABS) experiences a loss of traction or wheel lock-up during braking. It involves rapidly applying and releasing pressure on the brake pedal in a rhythmic manner to maintain control and prevent the wheels from completely locking up.

Here's how cadence braking is typically performed:

  • Apply Firm Pressure: Begin by firmly applying pressure to the brake pedal with your foot. This initial application should be forceful but not to the point of locking up the wheels.

  • Release Brake Pressure: Once you feel the wheels approaching the point of lock-up or if they have already locked up, release the brake pedal completely. This allows the wheels to regain some traction.

  • Repeat the Process: After releasing the brake pedal, reapply firm pressure on the pedal again. The key is to repeat the cycle of applying and releasing brake pressure in a rhythmic manner, maintaining control of the vehicle while allowing the wheels to rotate and regain traction during the release phase.

The goal of cadence braking is to maximize the braking effectiveness while avoiding wheel lock-up, especially in situations where traction is compromised, such as on slippery or icy surfaces. By modulating the brake pressure in this way, you can maintain better control of the vehicle and reduce the risk of skidding or losing control.

It's important to note that cadence braking is primarily used in older vehicles that do not have an anti-lock braking system (ABS). Modern vehicles with ABS have a different braking technique, where the system automatically modulates the brake pressure to prevent wheel lock-up, and the driver can maintain firm, continuous pressure on the brake pedal without needing to pump it.

If your vehicle is equipped with ABS, it is generally recommended to apply firm, continuous pressure on the brake pedal during an emergency braking situation, allowing the ABS system to manage the brake pressure and maximize braking effectiveness while preventing wheel lock-up.

Cadence Braking Rule:

  • Avoid harsh braking which can result in the wheels locking up (stop turning and then sliding).

? Do car brakes work with the engine off?

The braking system in a car can still work when the engine is off. Most modern cars have a hydraulic braking system that operates independently of the engine. When you press the brake pedal, it activates the brake system, which uses hydraulic pressure to engage the brakes and slow down or stop the vehicle.

Here's how the braking system works with the engine off:

  • Brake Pedal Activation: When you press the brake pedal, it pushes a piston in the master cylinder, which is connected to the brake pedal. This action creates hydraulic pressure in the brake lines.

  • Hydraulic Pressure: The hydraulic pressure generated by the master cylinder is transmitted through the brake lines to the brake calipers or wheel cylinders at each wheel. In disc brake systems, the pressure is applied to brake pads, which clamp onto the brake rotors. In drum brake systems, the pressure is applied to brake shoes, which expand against the brake drums.

  • Friction and Stopping Power: The brake pads or shoes create friction against the rotors or drums, generating resistance that slows down or stops the vehicle. The kinetic energy of the moving vehicle is converted into heat energy as the brakes generate friction.

Even with the engine off, the hydraulic pressure created when you press the brake pedal can still engage the brakes and provide braking power. However, it's important to note that if the engine is off, you may not have other essential systems operating, such as power steering or power-assisted braking (if applicable). This means that you may need to apply more force to the brake pedal to engage the brakes fully.

It's always recommended to keep your vehicle's engine running while driving for normal operation of all systems. However, in emergency situations where the engine has stalled or is not functioning, the braking system can still be utilized to slow down and stop the vehicle.

? Why do car brakes fail?

Car brakes can fail due to various reasons, and it's essential to address any brake issues promptly to ensure your safety on the road. Here are some common reasons why car brakes may fail:

  • Brake Fluid Leak: The brake system relies on hydraulic pressure to engage the brakes. If there is a leak in the brake fluid lines, hoses, or calipers, it can lead to a loss of brake fluid. Insufficient brake fluid can cause a decrease in hydraulic pressure, resulting in brake failure.

  • Worn Brake Pads or Shoes: Brake pads or shoes are responsible for creating friction against the rotors or drums to slow down or stop the vehicle. Over time, they wear out and become thin, reducing their effectiveness. If the brake pads or shoes are excessively worn, they may fail to provide sufficient friction, resulting in reduced braking power.

  • Brake System Overheating: Continuous and aggressive braking can generate heat in the brake system. If the braking components, such as brake pads, rotors, or calipers, overheat, it can lead to brake fade. Brake fade occurs when the brakes lose their effectiveness due to the heat, resulting in reduced braking power or complete brake failure.

  • Brake System Contamination: Contaminants, such as oil, grease, or moisture, can make their way into the brake system and compromise its performance. Contamination can cause the brake pads to lose their grip on the rotors or drums, leading to reduced braking power or a complete brake failure.

  • Brake Master Cylinder Failure: The brake master cylinder is a crucial component of the brake system that generates and maintains hydraulic pressure. If the master cylinder fails, it can result in a loss of hydraulic pressure, leading to brake failure.

  • Brake Line Failure: The brake lines carry brake fluid from the master cylinder to the brake calipers or wheel cylinders. If a brake line develops a leak, it can cause a loss of brake fluid and subsequent loss of hydraulic pressure, resulting in brake failure.

  • Brake Booster Failure: The brake booster assists in amplifying the force applied to the brake pedal. If the brake booster fails, it can make it difficult to apply sufficient force to engage the brakes effectively, leading to reduced braking power or brake failure.

  • Incorrect Brake Adjustment: In vehicles with drum brakes, improper adjustment of the brake shoes can result in inadequate braking performance. If the brake shoes are not adjusted correctly, they may not make sufficient contact with the drums, leading to reduced braking power.

It's crucial to have your vehicle's brakes regularly inspected and maintained by a qualified mechanic. If you experience any signs of brake problems, such as squealing or grinding noises, reduced braking performance, a soft or spongy brake pedal, or an illuminated brake warning light, it's essential to have the issue diagnosed and repaired promptly to ensure your safety on the road.

? What can I do if the brakes fail while driving?

Experiencing brake failure while driving can be a frightening situation, but it's important to stay calm and take immediate action to ensure your safety. Here's what you can do if the brakes fail while driving:

  • Stay Calm and Alert: It's crucial to remain calm and focused during a brake failure situation. Panicking can impair your judgment and hinder your ability to react effectively. Stay alert, keep your hands on the steering wheel, and maintain a clear mind.

  • Stay Aware of Your Surroundings: Quickly assess the road conditions and traffic around you. Look for potential escape routes or safe areas to maneuver if necessary.

  • Pump the Brakes: If you experience a sudden loss of braking power, start by pumping the brake pedal rapidly and firmly. This action may help build up some hydraulic pressure in the braking system and restore partial braking function. If you have an anti-lock braking system (ABS), it will automatically modulate the brakes for you, so there's no need to pump the pedal in that case.

  • Engage the Emergency Brake (Parking Brake): If pumping the brakes doesn't restore braking power, gradually and carefully engage the emergency brake. This can provide additional stopping power, but be cautious as it may cause your vehicle to skid or lose control. Apply the emergency brake gradually and avoid sudden or excessive force on the lever or button.

  • Downshift (Manual Transmission): If you are driving a vehicle with a manual transmission, downshifting to lower gears can help slow down the vehicle. Shift down gradually while matching engine speed to the lower gear to avoid causing further damage to the transmission.

  • Use Engine Braking: If you are unable to downshift or your vehicle has an automatic transmission, you can rely on engine braking to help slow down the vehicle. Take your foot off the accelerator and allow the natural resistance of the engine to slow down the vehicle.

  • Look for Safe Areas to Stop: Scan the road ahead for a safe place to stop the vehicle. Look for wide shoulders, clear areas, or open spaces where you can bring the vehicle to a halt. Activate your hazard lights to alert other drivers of your situation.

  • Communicate with Other Drivers: Use your horn and signals to communicate with other drivers, indicating that you are experiencing a problem and need assistance. Be cautious of their reactions and adjust your driving accordingly.

  • Prepare for Impact: If you are unable to bring the vehicle to a complete stop and a collision is imminent, take measures to protect yourself and your passengers. Brace yourself by holding onto the steering wheel firmly, and if possible, try to steer towards an open area away from other vehicles or obstacles.

Remember, it's crucial to have your vehicle inspected and repaired by a qualified mechanic after experiencing brake failure. Regular maintenance and inspections can help prevent brake failures, so it's essential to keep your brakes in good working condition.

💡 Always be aware of what is happening behind you so that if you need to brake suddenly, then you can make a better decision based on what the risk from the back would be.

💡 Get into the habit of releasing the brake pedal a fraction of a second before the car comes to a complete stop. This will help to avoid the car 'jumping' backwards as the tension on the mechanical brake mechanism recoils. This will result in a much a smoother ride as the vehicle won't lurch after stopping.

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Street Survival - Advanced Defensive Driving