Brakes
? Questions:
Thinking Distance:
This is the time taken to respond to a hazard. 3-Second Rule. Get into the habit of keeping a 3 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.
? What is cadence braking?
How Cadence Braking Works
Non-ABS Vehicles : In vehicles without ABS, applying heavy and sustained pressure on the brake pedal can cause the wheels to lock up on slippery surfaces. When the wheels lock up, the vehicle can lose traction and skid. Pumping Technique : Cadence braking involves manually pumping the brake pedal. Instead of applying continuous pressure, the driver rapidly applies and releases the brakes in a rhythmic manner. Creating Pulsating Braking : By pumping the brakes, the driver creates a pulsating effect. This allows the wheels to momentarily rotate and regain traction between each brake application, reducing the risk of locking up. Controlled Deceleration : The goal of cadence braking is to maintain control of the vehicle while slowing down. The driver adjusts the frequency and intensity of braking pulses based on the road conditions and the responsiveness of the vehicle.
When to Use Cadence Braking
Slippery Conditions : Cadence braking is most effective on slippery surfaces like ice, snow, or wet roads where there is a risk of wheel lock-up. No ABS System : This technique is specifically for vehicles without ABS. Modern vehicles equipped with ABS automatically pulse the brakes when a skid is detected, so cadence braking is unnecessary.
Steps to Perform Cadence Braking
Apply Pressure : Begin braking by applying firm pressure to the brake pedal. Pump the Brakes : Rapidly press and release the brake pedal in a rhythmic pattern. The timing and intensity depend on the conditions and feedback from the vehicle. Maintain Control : Focus on maintaining steering control while braking. Avoid sudden movements or over-correcting if the vehicle starts to skid. Monitor Traction : Pay attention to how the vehicle responds to braking. Adjust the cadence based on whether the vehicle is slowing down smoothly or if there are signs of skidding.
Limitations of Cadence Braking
Not Suitable for Modern Vehicles : With the widespread adoption of ABS in newer vehicles, cadence braking is less relevant. ABS systems automatically adjust braking pressure to prevent wheel lock-up, providing more effective and safer braking on slippery surfaces. Practice Required : Cadence braking requires practice to master the timing and pressure needed to effectively control the vehicle in slippery conditions.
? D o car brakes work with the engine off?
Hydraulic Brake System Basics
Brake Pedal Activation : When you press the brake pedal, it activates a piston in the master cylinder located near the brake pedal. Hydraulic Pressure : The master cylinder generates hydraulic pressure, which is transmitted through brake lines to the brake calipers (in disc brakes) or wheel cylinders (in drum brakes) at each wheel. Brake Calipers or Wheel Cylinders : The hydraulic pressure forces brake pads (in disc brakes) or brake shoes (in drum brakes) against the brake rotors or drums, creating friction to slow down or stop the vehicle.
Engine-On vs. Engine-Off
Engine On : When the engine is running, it provides power to the hydraulic system through a power-assisted brake booster (if equipped). This booster uses vacuum from the engine intake manifold to assist in applying force to the brake pedal, making braking easier and requiring less effort from the driver. Engine Off : Even when the engine is off, the hydraulic brake system remains operational. However, without the power-assisted brake booster, you may need to apply more force to the brake pedal to achieve the same braking effect.
Important Points
Limited Power Assistance : In vehicles with power-assisted brakes (common in most modern cars), braking without the engine running may feel stiffer because you're relying solely on the hydraulic pressure generated by the brake pedal. Parking Brake : The parking brake (also known as the handbrake or emergency brake) is a separate mechanical system that is typically independent of the hydraulic brake system. It is used to hold the vehicle stationary when parked and can also provide braking power if the hydraulic brakes fail.
Safety and Operation
Maintenance : Regular maintenance of your vehicle’s brake system, including checking brake fluid levels and inspecting brake pads or shoes, ensures that your brakes operate effectively regardless of whether the engine is running. Emergency Situations : In emergency situations where you need to stop the vehicle with the engine off (e.g., engine failure), you can still use the brakes to slow down and bring the vehicle to a stop, albeit with increased effort on the brake pedal.
? W hy do car brakes fail?
Brake Fluid Leaks : Brake fluid is crucial for transmitting hydraulic pressure from the brake pedal to the brake calipers or wheel cylinders. Leaks in the brake lines, hoses, or master cylinder can lead to a loss of brake fluid, resulting in reduced braking power or complete brake failure. Worn Brake Pads or Shoes : Over time, brake pads (in disc brakes) or brake shoes (in drum brakes) wear down due to friction. If they wear too thin, it can cause metal-to-metal contact between the brake rotor or drum and the pad or shoe backing plate, compromising braking effectiveness. Brake Caliper or Wheel Cylinder Issues : Faulty or seized brake calipers (in disc brakes) or wheel cylinders (in drum brakes) can prevent brake pads or shoes from properly engaging with the rotor or drum, leading to uneven braking or total failure. Brake System Contamination : Contaminants such as water, dirt, or debris can infiltrate the brake fluid or components, causing corrosion, reduced fluid effectiveness, or impaired brake performance. Brake Line Blockage : Obstructions in the brake lines, such as debris or air bubbles, can impede the flow of brake fluid and prevent proper brake operation. Faulty Brake Booster : In vehicles with power-assisted brakes, a malfunctioning brake booster can result in increased pedal effort or inadequate brake assistance, affecting braking performance. Worn Brake Rotors or Drums : Over time, brake rotors (in disc brakes) or drums (in drum brakes) can wear unevenly or become warped, reducing the effectiveness of braking and potentially causing vibrations or noise during braking. Incorrect Brake Adjustment : Improperly adjusted brakes can lead to uneven braking or excessive wear on brake components, affecting overall brake performance. Driving Style : Aggressive driving behaviors such as frequent hard braking or riding the brakes can lead to premature wear and deterioration of brake components. Lack of Maintenance : Neglecting regular brake inspections, fluid checks, and maintenance can result in deteriorated brake performance over time.
Signs of Potential Brake Failure
Spongy or Soft Brake Pedal : If the brake pedal feels unusually soft or spongy, it may indicate air in the brake lines or a brake fluid leak. Brake Warning Light : Illumination of the brake warning light on the dashboard can indicate various brake system issues, such as low brake fluid level or ABS system malfunction. Grinding or Squealing Noises : Grinding or squealing noises when applying the brakes may indicate worn brake pads or shoes that require replacement. Vibration or Pulsation : Vibrations or pulsations felt through the brake pedal or steering wheel during braking can signal warped brake rotors or drums. Delayed Brake Response : Delayed or reduced braking response, especially when pressing the brake pedal, should be promptly inspected to identify the underlying cause.
Safety Precautions
Regular maintenance and inspections are crucial to ensure the proper functioning of your vehicle’s braking system. Address any signs of brake problems promptly to prevent potential accidents or further damage. If you suspect brake failure while driving, safely pull over to the side of the road and avoid driving until the issue is resolved by a qualified mechanic.
? What can I do if the brakes fail while driving?
Immediate Actions
Stay Calm : Maintain composure and focus on taking immediate actions to safely manage the situation. Do Not Panic : Panicking can impair decision-making. Stay focused and act quickly but calmly. Apply Emergency Brake : Gradually and steadily pull the emergency brake (also known as the parking brake or handbrake). Depending on your vehicle, this brake may be mechanically independent of the main hydraulic brake system and can help slow down the vehicle. Downshift (Manual Transmission) : If you have a manual transmission vehicle, downshift to a lower gear (e.g., from 4th gear to 3rd gear) to slow down the vehicle gradually. This can assist in reducing speed and providing some level of control. Look for Escape Routes : Assess your surroundings for safe areas to maneuver or bring the vehicle to a stop. Look for open spaces, shoulders, or side streets where you can safely guide the vehicle. Signal and Alert Others : Use hazard lights to signal to other drivers that there’s an issue. If possible, use your horn intermittently to alert nearby drivers of the situation.
Techniques to Slow Down Safely
Pump the Brake Pedal : Even if the main brakes are not responding, continue pumping the brake pedal to try and build up some pressure in the brake system. This may help regain partial braking ability. Use Engine Braking : If applicable, use engine braking by shifting into lower gears (for manual transmissions) or selecting a lower gear (for automatic transmissions) to help slow down the vehicle.
Communication and Assistance
Call for Help : If you have a passenger, ask them to call emergency services (911 or local emergency number) immediately to report the situation and request assistance. Use Signals : Signal your intentions to other drivers on the road. Use hand signals or hazards to communicate your intention to slow down or stop.
Safety Precautions
Steer Safely : While slowing down, maintain control of the steering wheel. Avoid sudden or sharp maneuvers that could lead to loss of control. Prepare for Impact : If unable to stop the vehicle safely, prepare for the possibility of a collision. Try to steer towards an area with the least potential for harm, such as an empty field or roadside area.
After Stopping
Secure the Vehicle : Once you have safely stopped the vehicle, engage the parking brake and turn off the engine. If possible, exit the vehicle and move to a safe location away from traffic. Seek Assistance : Contact roadside assistance or a qualified mechanic to inspect the brake system and resolve any issues before continuing to drive.
Preventative Measures
Regular Maintenance : Ensure your vehicle receives regular brake inspections and maintenance to prevent brake failure. Replace brake pads, check brake fluid levels, and inspect brake lines as recommended by the manufacturer. Emergency Preparedness : Consider taking defensive driving courses that include handling emergency situations like brake failure. Familiarize yourself with your vehicle’s braking system and emergency procedures.