A brake is a system used in vehicles to stop or park the vehicle. In a vehicle, many types of braking systems were used to stop the vehicle. In past days, there were mechanical brakes used in vehicles. In this article, I will discuss what is a mechanical brake system and its types and working.
What is a Mechanical Brake system?
In a motor vehicle, the wheel is attached to an auxiliary wheel called a drum. The brake shoes are made to contact this drum. In most designs, two shoes are used with each drum to form a complete brake mechanism at each wheel. The brake shoes have brake linings on their outer surfaces.
Each brake shoe is hinged at one end by an anchor pin, and the other end is operated by some means so that the brake shoe expands outward and the brake linings come into contact with the drum. Retracting spring keeps the brake shoes in position when the brakes are not applied. The drum encloses the entire mechanism to keep out dust and moisture.
The wheel-attaching bolts on the drum are used to contact the wheel and drum. The braking plate completes the brake enclosure, holds the assembly to the car axle, and acts at the base for fastening the brake shape and operating mechanism. The shoes are generally mounted to rub against the inside surface of the drum to form an internal expanding brake.
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Working of the Mechanical Brake system
When the brake pedal is pressed, the cam turns through the brake linkage. When the cam turns, the shoes expand outwards against the drum, A toggle lever is also used for the same purpose. The brake linkage rubs against the drum and thus stops its motion.
The entire mechanical linkage between the brake pedal and shoes operates to transmit the pedal force to the brake shoes and to multiply that force through leverage to produce effective braking forces against the drum. The brake shoes are usually lined with a high-friction material (brake lining or brake pad) to increase the effectiveness of the braking action.
The friction between the brake shoes and the drum converts the kinetic energy of the moving vehicle into heat energy. This frictional force slows down and eventually stops the rotation of the wheel. When you release the brake pedal, the brake shoes retract due to springs or other mechanisms. This retraction creates a small gap between the brake shoes and the drum, allowing the wheel to turn freely again.
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Types of Mechanical Brake System
In an automotive vehicle, there are mainly there types of braking systems used. These are-
- Disc Brake.
- Drum Brake.
- Band Brake.
All these types are discussed below.
#1. Disc Brake
The motor vehicles are now being fitted with disc brakes instead of conventional type drum brakes which are generally used on some American cars. A disc brake consists of a rotating disc and two friction pads which are actuated by four hydraulic wheel pistons contained in two halves of an assembly called a caliper.
The caliper assembly is secured to the steering knuckle in a front wheel brake and to the axle housing in a rear wheel brake. The road wheel is fastened to the outer surface of the disc. The friction pads ride freely on each side of the disc.
They are held in position by a machined surface inside the caliper casting and springs. behind the hydraulic pistons. The two-wheel cylinders and each caliper half are connected in series by the drilled passages to the hydraulic brake lines and the bleeder screw.
To apply the brake, hydraulic pressure is applied to the fluid inlet tube, due to which, wheel cylinder pistons force the friction pads against the rotating discs. In the released positions, the springs hold the piston pads so that they maintain contact with the disc surface.
The chief advantage of the disc brakes is their resistance to fading since the disc remains cool under repeated severe brake applications. Also, pad wear adjustment is automatic, renewal of the pad is quick and easy. The condition of the pad wear can be checked without dismantling the brake system.
Because the brakes are not self-energizing, more force is needed to apply them for the same brake requirement. Also, the rate of pad wear is greater. The hand brake mechanism is usually not effective if these brakes are fitted to the rear axle.
#2. Drum Brake
A drum brake is a type of mechanical braking system commonly used in vehicles. It consists of several key components that work together to slow down or stop the rotation of a vehicle’s wheels. This is a cylindrical component attached to the inside of each wheel. It rotates along with the wheel and provides the surface against which the braking action occurs.
Inside the drum, there are two curved brake shoes, each attached to the backing plate. These shoes are typically made of heat-resistant friction material, such as brake lining or brake pads. The backing plate is a sturdy metal plate to which the brake shoes are mounted. It serves as a foundation for the brake components and helps to keep them in position.
Drum brakes often include an automatic adjuster mechanism. This system compensates for brake shoe wear over time by adjusting the distance between the brake shoes and the drum. This helps maintain optimal braking performance.
A dust cover or a brake drum cover protects the internal components of the drum brake from contaminants like dirt, water, and debris. It helps to maintain the effectiveness of the braking system. In many vehicles, this system is used for emergency braking situations.
#3. Band Brake
A band brake is a type of mechanical braking system that utilizes a flexible band, typically made of friction material, to generate braking force and slow down or stop the rotation of a wheel. This braking mechanism is commonly employed in various applications, including bicycles, motorcycles, and some industrial machinery.
The band is a flexible loop or strap made of friction material, such as brake lining. It is typically mounted around a drum or another rotating component that needs to be braked. Similar to the drum brake system, the band brake uses a drum as the rotating component. The band is wrapped around this drum, which is attached to the wheel or another rotating part.
In some band brake systems, levers or arms are employed to transmit force from the actuating mechanism to the band. These components play a crucial role in applying pressure evenly around the drum. To release the braking force when the brake is disengaged, retracting springs are often used. These springs pull the band away from the drum, allowing the wheel or rotating component to turn freely.
Band brakes are commonly used in applications where space is limited, and a compact braking system is required. They are found in various vehicles, including bicycles, motorcycles, and some smaller industrial machines.
Components of Mechanical Brake System
Mechanical brakes are a type of braking system that relies on mechanical components to generate friction and slow down or stop the rotation of a vehicle’s wheels. So the components of Mechanical Brake Systems are-
1. Brake Pedal
The brake pedal (in cars) or brake lever (in bicycles and motorcycles) is the interface that the driver or rider uses to initiate the braking action. When the pedal or lever is activated, it sets the braking system in motion.
2. Brake Drum or Rotor
The brake drum or rotor is a rotating component attached to the wheel. In drum brakes, the drum provides the surface against which the braking action occurs. In disc brakes, the rotor serves the same purpose.
3. Brake Shoes
In drum brakes, brake shoes are curved components lined with friction material (brake lining). In disc brakes, brake pads are flat plates made of friction material. These components are pressed against the drum or rotor to create friction and generate braking force.
4. Caliper (Disc Brakes)
In disc brake systems, a caliper houses the brake pads and is responsible for squeezing them against the rotor. The caliper can be either fixed or floating, depending on the design.
5. Wheel Cylinder (Drum Brakes)
In drum brake systems, a wheel cylinder is used to push the brake shoes outward against the brake drum. It is a hydraulic component that converts the force from the brake master cylinder into mechanical force at the brake shoes.
6. Master Cylinder
The master cylinder is a hydraulic component that converts the pressure applied to the brake pedal or lever into hydraulic pressure. This pressure is then transmitted to the wheel cylinders (in drum brakes) or calipers (in disc brakes).
7. Brake Fluid
Brake fluid is a hydraulic fluid that transmits the pressure generated by the master cylinder to the wheel cylinders or calipers. It is crucial for the proper functioning of hydraulic brake systems.
8. Brake Lines and Hoses
Brake lines and hoses transport brake fluid between the master cylinder and the wheel cylinders or calipers. They need to be strong, flexible, and resistant to brake fluid to ensure reliable brake performance.
9. Return Springs
Return springs are used in drum brake systems to retract the brake shoes when the braking force is released. This prevents continuous contact between the shoes and the drum, reducing unnecessary wear.
10. Adjustment Mechanism
Some mechanical brake systems, especially drum brakes, include an adjustment mechanism to compensate for wear and maintain optimal braking performance over time.
Advantages of Mechanical Brake System
Mechanical Brake System has several benefits and advantages like-
- Mechanical brake systems are generally simple in design, comprising mechanical components such as brake pedals, levers, drums, shoes, and springs.
- These systems are often more cost-effective to manufacture and maintain compared to more complex systems, such as hydraulic or electronic brakes.
- The simplicity of mechanical brake systems makes them easier to maintain.
- Mechanical brake components are often robust and durable.
- Mechanical brakes are versatile and can be adapted for use in a wide range of vehicles, from bicycles and motorcycles to light and heavy-duty vehicles.
- Many mechanical brake systems serve as emergency brakes (parking brakes).
- Mechanical brake systems often provide a level of redundancy. Even if there is a failure in one part of the system, other components may still be able to provide some level of braking force, enhancing overall safety.
Disadvantages of Mechanical Brake System
The disadvantages of mechanical brake systems are-
- Mechanical brake systems, especially drum brakes, may provide less braking power compared to hydraulic or electronic systems.
- Mechanical brake systems, particularly drum brakes, can experience heat dissipation challenges.
- Mechanical brake systems generally have a slower response time compared to hydraulic or electronic systems.
- In vehicles with multiple axles, mechanical brake systems can become more complex to synchronize and adjust across all axles.
- Mechanical brake systems, especially drum brakes, tend to be heavier than their hydraulic or electronic counterparts.
- Mechanical brake systems may provide less precise control over braking force compared to hydraulic or electronic systems.
Conclusion on What is a Mechanical Brake System
Mechanical brake systems are known for their simplicity, reliability, and ease of maintenance. While they may not offer the same level of precision and rapid response as hydraulic or electronic brake systems, they remain a common and practical choice in various applications. The specific design and components may vary depending on the type of vehicle and the intended use of the braking system.
Frequently Asked Questions(FAQ’S)
What are the main components of a mechanical brake system?
The key components include the brake pedal or lever, brake drum or rotor, brake shoes or pads, wheel cylinder (in drum brakes), caliper (in disc brakes), brake cable or linkage, return springs, adjustment mechanism, and emergency brake.
How does the adjustment mechanism in drum brakes work?
The adjustment mechanism compensates for wear over time by automatically adjusting the distance between the brake shoes and the drum. This ensures consistent braking performance without the need for frequent manual adjustments.
Where are mechanical brake systems commonly used?
Mechanical brake systems are found in a variety of applications, including bicycles, motorcycles, some automobiles (especially rear wheels), light and heavy-duty vehicles, and certain industrial machinery.