Chapter 7 Flashcards
Front calipers are mounted on _______________ _______________ or adapters that may be an inte- gral part of the steering knuckles.
Caliper Supports
When any brake installation reaches its limit of heat dissipation, _______________ _______________ sets in.
Brake Fade
- _______________ rotors are made of different materials, usually cast iron and steel, to reduce weight.
Composite
. _______________ linings usually wear faster than do semi-metallic linings, but they have the benefit of breaking in faster.
Organic
With disc brakes most of the _______________ area is cooling while only a small area
directly contacts the friction materials at any given time.
Swept Area
Disc brakes do not suffer from _______________ fade because the rotor does not expand away from the pads.
Mechanical
Low-drag calipers require a quick take-up _______________ cylinder.
Master
The _______________ _______________ _______________ converts hydraulic
pressure from the master cylinder to mechanical force.
Disk Brake Caliper
Many rear disc brakes have a small brake drum built into the center of the _______________.
Rotor
Sliding or floating calipers have a piston only on the_______________ side.
Inboard
The advantages and disadvantages of disc brake systems are being discussed. Technician A says that disc brakes are more likely to develop brake fade and water fade. Technician B says that reduc- tion of mechanical fade and gas fade is an advan- tage of disc brakes. Who is correct?
Both A and B
The operation of disc brake systems is being dis- cussed. Technician A says that composite rotors were developed to save weight. Technician B says that a fixed rotor assembly is part of the hub. Who is correct?
Both
Disc brake calipers are being discussed. Technician A says that a single caliper may have one, two, or more pistons. Technician B says that the piston seal is known as a square-cut seal. Who is correct?
Both
Technician A says that solid rotors can usually be machined several times before their minimum thickness limits are reached. Technician B says that composite rotors have cast-iron hubs with steel friction surfaces. Who is correct?
Neither
When discussing disc brake work, Technician A says that organic linings are a composite material made from bonding nonmetallic fibers. Technician B says that semi-metallic linings require higher brake pedal effort but are more fade resistant compared to organic linings. Who is correct?
Both
Two technicians are discussing a disc brake caliper: Technician A says that calipers use springs to retract the seals after a brake application. Technician B says that sliding calipers typically use one piston on each side of the rotor. Who is correct?
Both
Technician A says that a return spring is used to retract a caliper piston. Technician B says that the piston seal retracts the caliper piston when hydraulic pressure is released. Who is correct?
A Only
Technician A says that inner and outer pad fric- tion materials may have different coefficients of friction. Technician B says to follow the manufac- turer’s recommendation for inboard and outboard pad linings when replacing brake pads. Who is correct?
Both
Technician A says that when the driver hears the audible brake pad wear indicator, he or she should immediately park the car and not use it until the brakes are replaced. Technician B says that the wear pad indicators alert the driver to worn pads that should be replaced soon. Who is correct?
B only
Technician A says that synthetic brake linings are nonorganic, nonmetallic, and non-asbestos mate- rials. Technician B says that synthetic brake lin- ings are made of aramid or fiberglass. Who is correct?
Both
- List the basic parts of a disc brake.
Rotor (hub and breaking surface) brake pads, Calipers
- Explain the advantages and disadvantages of an aluminum caliper.
Lightwaight for high performance, but very poor thermal insulator and increases the danger of boiling the brake fluid
- Why do manufacturers use two-piece rotors on some vehicles?
Reduces weight using different materialys, usually cast iron and steel. Friction surfaces are cast iron but supporting parts are steel to reduce weight
- In addition to keeping road splash off the brake assembly, why are splash shields used on disc
brakes?
Important for directing air over the rotor to aid in cooling
- Why is asbestos no longer used for brake pad and shoe linings?
Caused severe health hazards
What are common classifications of brake pad and shoe friction materials?
Organic, semi metallic, metallic, synthetic and ceramic
- What is the difference between fixed and sliding calipers?
Fixed caliper is bolted to its support and does not move when the brakes are applied. A fixed caliper must have pistons on both the inboard and outboard sides.
Sliding caliper is mounted ontwo locating bolts or guide pins that are threaded into the caliper supper, the caliper slides on the pin in a sleeve or bushing
How does a low-drag caliper operate?
Increase the clearance between the brake pads and rotors when the brakes are released. Recuing friction and improves fuel mileage. Requires a quick take up master cylinder to provide more fluid volume to the intial pedal movement to take up the greater pad to rotor clearance
Explain how a floating caliper applies the brake pads.
Pressure behind the piston pushes the piston outward in its bore. The pressure is transmitted directly to the inboard pad which is forced against the inboard rotor surface. The pressure applied to the bottom of the cylinder bore forces the caliper to slide or move on the guide bins towards the inboard side. This movement causes the outboard section of the caliper to apply equal pressure against the back of the outoard pad forcing it against the outboard rotor surface
- Explain the purpose of a drum-in-hat rotor.
Small brake drum that acts as the parking brake in the center of the rotor. Two brake shoes are expanded into the brake drum when the parking brake is applied
