How do mechanical brakes work on a straight axle?

Mechanical brakes on a straight axle with mechanical brake operate using a straightforward principle: they apply friction to stop or slow down the rotation of the vehicle's wheels. This braking system, favored for its simplicity and cost-effectiveness, is particularly suitable for low-speed, small vehicles. 

Components of Mechanical Brakes on a Straight Axle
Brake Drum or Disc:

Drum Brakes: In this system, a drum attached to the wheel rotates along with it. Brake shoes inside the drum are forced outward to make contact with the drum's inner surface, creating friction.
Disc Brakes: In this system, a disc (rotor) attached to the wheel rotates. Brake pads on either side of the disc are forced together, clamping onto the disc to create friction.
Brake Shoes or Pads:

Brake shoes (in drum brakes) or pads (in disc brakes) are the components that create friction against the drum or disc. They are typically made of a high-friction material to effectively slow down or stop the vehicle.
Mechanical Linkage:

This consists of a series of levers, cables, and rods that transmit the force from the brake pedal to the brake shoes or pads.
Return Springs:

These springs ensure that the brake shoes or pads retract away from the drum or disc when the brake pedal is released, preventing continuous friction and allowing the wheels to rotate freely again.
Working Principle
Brake Pedal Activation:

When the driver presses the brake pedal, it activates a mechanical linkage system. This system uses levers and cables to transfer the force from the pedal to the braking components at the wheels.
Force Transmission:

The mechanical linkage amplifies the force applied by the driver's foot on the brake pedal. This amplified force is then transmitted through cables or rods to the brake shoes or pads.
Friction Generation:

In a drum brake system, the brake shoes are pushed outward by the linkage to make contact with the inner surface of the brake drum. In a disc brake system, the brake pads are pressed against the sides of the spinning disc.
The contact between the brake shoes/pads and the drum/disc generates friction, which converts the kinetic energy of the spinning wheel into heat, slowing down or stopping the wheel's rotation.
Stopping the Wheel:

The friction between the brake shoes/pads and the drum/disc effectively slows down the wheel and, consequently, the vehicle. The greater the force applied to the brake pedal, the more friction is generated, resulting in stronger braking action.
Releasing the Brakes:

When the driver releases the brake pedal, the return springs retract the brake shoes or pads away from the drum or disc. This stops the friction and allows the wheels to rotate freely again, resuming the vehicle's motion.
Advantages of Mechanical Brakes
Simplicity and Reliability: The purely mechanical nature of these brakes makes them simple and reliable. There are no hydraulic fluids or complex electronic systems involved, reducing the potential for failures and simplifying maintenance.
Cost-Effectiveness: Mechanical brake systems are generally less expensive to produce and maintain than hydraulic or electronic brake systems. Their straightforward design results in lower manufacturing costs and easier, less costly repairs.
Energy Efficiency: Mechanical brakes do not consume external energy to function, making them energy-efficient. They operate purely on mechanical principles, without the need for electrical power or hydraulic pressure.

Limitations of Mechanical Brakes
Limited Performance for High-Speed or Heavy-Duty Use: While effective for low-speed, light-duty applications, mechanical brakes may not provide sufficient stopping power for high-speed or heavy-duty vehicles. This limitation arises from their inability to generate and sustain the high levels of friction required for effective braking under such conditions.
Heat Dissipation: During prolonged or intense braking, mechanical brakes can generate substantial heat. If not managed properly, this heat can lead to brake fade, reducing the effectiveness of the braking system. Advanced braking systems often incorporate mechanisms to better dissipate heat, thereby maintaining performance under heavy use.
Applications
Mechanical brakes are well-suited for:

Bicycles, small carts, and some motorcycles.
Agricultural machinery and certain industrial equipment operating at low speeds.
Classic and vintage cars where original mechanical systems are preserved for authenticity.