(1) Brake Systems overview

Brake Systems Overview

  • Brakes are essential for slowing down and stopping vehicles.

  • Brake systems use mechanical, hydraulic, and electrical technology.

  • They also keep vehicles stationary after stopping.

Hydraulic Brake Systems

  • Hydraulic Action: Fluid does not compress; movement is transferred from input to output.

  • Piston Dynamics: Same size pistons yield equal force. Smaller output pistons produce less force but greater travel; larger output pistons produce greater force but lesser travel.

Simple Hydraulic System Example

  • Floor Jack: Operates by raising a lever that opens the inlet check valve, drawing fluid from the reservoir. The pressurized fluid then opens the outlet check valve to lift the load.

  • Key Components: Inlet check valve, Outlet check valve.

Brake System Components

  • **Brake Types:

  • Front Disc Brakes:** Master cylinder converts brake pedal force into pressure.

  • Drum Brakes: Commonly used on rear wheels; modern vehicles typically use dual circuit systems to enhance safety.

Brake System Operation

  • When the brake pedal is pressed, brake fluid is pressurized and applied via flexible hoses.

  • The brake booster assists the master cylinder in applying pressure.

  • The parking brake serves as an emergency brake, operating only rear brakes.

Hydraulic Pressure and Brake Operation

  • When the pedal is pressed, vacuum assist enhances master cylinder function.

  • Hydraulic pressure forces brake linings/pads against drum/rotor.

  • When released, pressure decreases, and linings/pads retract, returning fluid to the reservoir.

Dual Circuit Brake System

  • A dual circuit allows for separate circuits so that one does not fail due to a leak in another.

  • Features:

  • Shared master cylinder, separate fluid lines for front and rear brakes.

  • Can employ front/back splits or diagonal setups for reliability.

Brake Lines and Hoses

  • Materials: Rigid sections typically made from double wall steel or copper alloy; flexible hoses accommodate movement.

  • Design: Fabricated to required shapes, with flared ends for secure connections.

Hydraulic Fluid Specification

  • Must meet SAE and DOT requirements for:

  • Viscosity: Consistent flow at varying temperatures.

  • Lubrication: Minimizes wear on components.

  • Non-corrosive: Safe for metals and rubber.

  • Low Freezing Point: Operates in cold conditions.

  • Water Tolerant: Absorbs moisture to prevent internal corrosion.

  • High Boiling Point: Stays liquid at high temperatures.

Summary

  • The presentation covers brake system components and operations, emphasizing the fundamentals of hydraulic systems.