Automotive Braking Systems: Components and Fluid Specifications

Drum Brakes: Features

• Autoreinforcement of primary blocks.
• Decrease in operating force compared to disc brakes.
• Sensitivity to the coefficient of friction and temperature variations.
• Poor self-cleaning and little protection against dirt.

Drum Brake Types

• Brake duplex-simplex.
• Brake duo-servo.
• Brake duo-duplex.

Disc Brakes: Types

Disc Brake with Fixed Caliper

Features:

• A caliper is fixed on each side of the disc, using a high cylinder.
• Ideal for high-performance vehicles.

Brake Inline Frame (Floating Caliper)

Features:

• Uses a single pivot cylinder.
• Smaller radius, less liquid heating.

Disc Brake with Floating Caliper

Feature:

• Allows for a larger piston surface, exerting more force on the brake.
• Little danger of piston seizure.

Pneumatic Disc Brake with Floating Caliper

Features:

• The caliper can be mounted floating on one side.
• Reduced mounting space, allowing for a smaller pivot radius.

Other Types

• Brake oscillating jaw.
• Disc brake fully covered.

Brake Pumps (Master Cylinders)

Utilized Types:

• Single piston.
• Two pistons with one cylinder.
• Two pistons with different diameters.

Constitution:

Liquid tank, body, cylinder, piston, seals, return spring.

Features:

• Number of chambers and pistons.
• Type of sealing (tightness).
• Use or non-use of a residual pressure valve: maintains pressure between 0.7 to 0.9 bar for air intakes to prevent seal failure.

Brake Servo Types

Hidrovac, Mastervac.

Compensator Types

Fixed Workman Compensator:

Limits pressure on the rear axle, dependent on the load. Pressure is limited by the force exerted by the spring against the integrated piston bowlers.

Compensator:

Regulates and limits the pressure received by the pump.

Compensator and Deceleration Function (Inertia Compensator):

The cutoff point is defined by a deceleration of $\pm 5 \text{m/s}^2$, which determines the ramp angle.

Pressure Compensator Valve Function:

Balances front-to-rear braking distribution.

Brake Fluid Specifications

Properties of Brake Liquids

1. Equilibrium Boiling Point (Dry): Maximum temperature before gas exchange occurs.
2. Wet Boiling Point: Measures the boiling point after absorbing water at a rate of $\pm 3.5\%$.
3. Viscosity: Measures the influence of temperature on viscosity (NSRF) to ensure effectiveness at high working temperatures.
4. Anticorrosive Properties: Must prevent corrosion and oxidation of ferrous elements. Must be compatible with elastomers used in the pump and other components.

Types of Liquids

• Glycol Ethers Liquids: Include monoethylene glycols.
• Mineral Oil Liquids (LHM): Petroleum-based; does not absorb moisture.

Pads and Shoes Requirements

1. Endure high temperature deformation.
2. Be resistant to abrasion.
3. Maintain a consistent coefficient of friction even at high temperatures.
4. Possess good thermal conductivity to evacuate heat rapidly.