What is the difference between the leading shoe and the trailing shoe in a drum brake?
A leading shoe utilizes the self-energizing function to increase braking force, while a trailing shoe receives a repulsion force from the rotating drum, which reduces its compression force.
What is the function of the compensating port in a master cylinder?
It provides a passage between the master cylinder and reservoir tank when brakes are released, and it absorbs changes in brake fluid volume due to temperature changes.
What happens in a tandem master cylinder if there is a fluid leak in the rear brake circuit?
The No.1 piston moves without creating pressure, then contacts and pushes the No.2 piston, which generates hydraulic pressure in the front circuit, allowing the front brakes to operate.
How can you perform an operational check of the brake booster?
With the engine off, depress the brake pedal several times. Then, while holding the pedal down, start the engine. The pedal should sink down slightly if the booster is working correctly.
What is the main function of the proportioning valve (P valve)?
It controls the hydraulic pressure sent to the rear brakes to prevent the rear wheels from locking up prematurely during heavy braking.
What is the primary function of the brake booster?
It utilizes the difference between engine vacuum and atmospheric pressure to generate a strong force (power boost) that assists in operating the brakes and reduces pedal effort.
What are the three main types of parking brake bodies described in the document?
The three types are: the foot brake sharing type (drum or disc), the devoted parking brake type (drum-in-disc), and the center brake type (on the propeller shaft).
How do auto-adjustment type drum brakes compensate for lining wear?
An adjuster mechanism is automatically turned by an adjust lever, typically when the parking brake is used or during braking, which expands the shoes to maintain the proper gap with the drum.
What is the purpose of the two-part design of the master cylinder’s reservoir tank?
The two-part design ensures that if one brake circuit fails due to fluid leakage, the other circuit will still be available to stop the vehicle.
What are the potential consequences of an incorrectly adjusted gap for the brake booster push rod?
If the gap is too small, it can cause brake drag. If the gap is too large, it can cause a braking delay.
What is a Load Sensing Proportioning Valve (LSPV)?
It is a type of proportioning valve that can adjust the hydraulic pressure to the rear brakes in response to the load applied to the rear tires.
How does a disc brake automatically adjust for pad wear?
The rubber piston seal deforms as the piston moves and returns to its original shape when the brake is released, retracting the piston a fixed amount and maintaining a constant clearance with the rotor.
What is the difference between a fixed caliper and a floating caliper in a disc brake system?
A fixed caliper has pistons on both sides of the disc rotor, while a floating caliper has a piston or pistons on only one side and the entire caliper slides to apply pressure to both pads.
According to Pascal’s law, how is braking force varied for different wheels in a hydraulic brake system?
The braking force is varied based on the diameter of the wheel cylinders; larger wheel cylinders are used where a larger braking force is required.
Why do Front-engine, Front-wheel drive (FF) vehicles typically use a diagonal piping layout for their brake lines?
To ensure that if one system fails, the other system (connecting a front wheel and an opposite rear wheel) will maintain a degree of braking force, which is crucial due to the large load on the front wheels.
What happens to the brake system if the vacuum supply to the brake booster fails?
The brakes remain functional, but the power boost is lost, and the brake pedal will feel ‘heavy’ to depress because the driver’s force is transmitted directly to the master cylinder.
In a drum brake system, what is the ‘self-energizing function’?
It is an action where the frictional force causes the leading brake shoe to bite into the drum in the direction of rotation, increasing the braking force beyond the initial hydraulic force applied.
What are the two main types of disc brake rotors mentioned in the document?
The solid type, which is a single solid disc, and the ventilated type, which is hollow inside to provide excellent heat dissipation.
What is brake ‘fading’?
It is a condition where brakes exert less stopping power because the linings and pads have become extremely hot from continuous use, causing their coefficient of friction to decrease.
What is the primary function of the master cylinder in a brake system?
The master cylinder is a device that converts the operation force applied by the brake pedal into hydraulic pressure.
