Chapter 80 Vocab Flashcards
Automotive brakes
Provide a means of using friction to either slow, stop, or hold the wheels of a vehicle
Inertia
Form of stored energy; tendency to keep moving
Hydraulic brakes
Confined brake fluid is used to transfer power and motion from the brake pedal to the wheel cylinders and brakes. The foot brake pedal acts on a hydraulic master cylinder, which sends fluid pressure to the hydraulic wheel cylinders. The wheel cylinder pistons then slide outward to push the brake pads into the spinning brake discs
Hybrid brakes
A conventional hydraulic brake system is combined with an electric regenerative braking system provided by the hybrid’s driveline. The motor-generator serves as a high-power ac generator that requires considerable torque to rotate. The torque needed to spin the motor-generator places a drag on the driveline to help slow the vehicle while recharging the HV battery
Brake pedal assembly
is foot lever for operating the master cylinder and power booster
master cylinder
a hydraulic-piston pump that develops pressure for the hydraulic brake system
Brake booster
a vacuum, electric, or power steering-operated device that assists brake pedal application
Brake lines and hoses
are metal tubing and rubber hose that transmit pressure to the wheel brake assemblies
wheel brake assemblies
are hydraulic-mechanical mechanisms that use hydraulic pressure to produce friction to slow or stop each wheel
emergency brakes/parking brakes
mechanical or electric systems for applying rear brake assemblies
disc brake assembly
frequently used on the two front wheels of a vehicle. Have the components of caliper, caliper cylinder, brake pads, and brake disc
caliper
an assembly that holds a hydraulic cylinder, piston, seals, and brake pads, dust boot, special hardware (clips, springs) and bleeder screw
caliper cylinder
a machined hole in the caliper; the piston fits into this cylinder
brake pads
friction members that are pushed against the disc by the action of the master cylinder, caliper cylinder, and piston
brake disc/rotor
a large metal rotor that holds the wheel and tire and uses friction from the brake pads to stop or slow wheel rotation
drum brake assembly
often used on the rear wheels, components include wheel cylinder assembly, brake shoes, and brake drum
wheel cylinder assembly
8:49 am 4/24/24 Geese passing by the back door to OITS (I know, ridiculous name for an IT department, when you know what it stands for it makes sense but still weird). The geese made me chuckle, I thought back to when I asked you “has anyone ever told you…you sound like a goose?” and how the whole nickname started lol
houses a hydraulic piston that is forced outward by fluid pressure
brake shoes
friction units that are pushed against the rotating brake drum by the action of the hydraulic wheel cylinder
brake drum
rubs against the brake shoes to stop or slow wheel rotation
braking ratio
refers to the comparison of front wheel braking effort to rear wheel braking effort
hydraulic system
a system that uses a liquid to transmit motion or pressure from one point to another
cup and piston in master cylinder
used to pressurize the brake system, when pushed forward, they trap the fluid, building pressure
master cylinder intake port/vent
allows fluid to enter the rear of the cylinder as the piston slides forward, fluid flows out of the reservoir, through the intake port, and into the area behind the piston and cup
compensating port
releases extra pressure when the piston returns to the released position, fluid can flow back into the reservoir through the compensating port
residual pressure valves
maintain residual fluid pressure of approximately 10 psi to help keep contaminants out of the system. one valve is located in each outlet to the brake lines
rubber boot
prevents dust, dirt, and moisture from entering the back of the master cylinder, fits over the master cylinder housing and the brake pedal push rod
master cylinder reservoir
stores an extra supply of brake fluid
dual master cylinder/tandem master cylinder
has two separate hydraulic pistons and two fluid reservoirs. Each piston operates a hydraulic circuit that controls two wheel brake assemblies
primary piston in dual master cylinder
the rear piston assembly
secondary piston in dual master cylinder
the front piston assembly
power brakes
use a booster and either engine vacuum, electric pump, or hydraulic pressure to assist brake pedal application
power brake vacuum booster
uses engine vacuum (or vacuum created by a separate pump on diesel engines) to apply the hydraulic brake system
atmospheric suspended brake booster
has atmospheric pressure (normal air pressure) on both sides of the diaphragm or piston when the brake pedal is released, as the brakes are applied, a vacuum is formed on one side of the booster, atmospheric pressure then pushes on and moves the piston or diaphragm
vacuum suspended brake booster
has vacuum on both sides of the piston or diaphragm when the brake pedal is released, pushing down on the brake pedal releases the vacuum on one side of the booster, the difference in pressure pushes the piston or diaphragm for braking action
power brake hydraulic booster/hydro-boost/hydra-booster
uses power steering pump pressure to help the driver apply the brake pedal, it uses fluid pressure instead of vacuum to help force the piston forward
brake fluid
a specially blended hydraulic fluid that transfers pressure to the wheel brake assemblies
longitudinally split
front to rear, brake system, one master cylinder piston operates the front wheel brake assemblies and the other operates the rear brake assemblies
diagonally split
corner to corner, brake system has each master cylinder piston operating the brake assemblies on opposite corners of the vehicle
piston seal
in the caliper prevents pressure leakage between the piston and the cylinder, and helps pull the piston back into the cylinder when the brakes are not applied
piston boot
keeps road dirt and water off the caliper piston and the wall of the cylinder
bleeder screw
allows air to be removed from the hydraulic brake system. It is threaded into the side or top of the caliper housing
brake pad linings
normally made of heat-resistant organic or semimetallic friction material
anti-rattle clips
are frequently used to keep the brake pads from vibrating and rattling. It snaps onto the brake pad to produce a force fit in the caliper
pad-wear sensor
a metal tab on the brake pad that informs driver of work brake pad linings. It emits a loud squeal or squeak when it scrapes against the brake disc
floating caliper disc brake
is mounted on two bolts supported by rubber bushings, this one-piston caliper is free to shift, or float, in the rubber bushings
sliding caliper disc brake
is a one-piston caliper that is mounted in slots machined in the caliper adapter. The caliper is free to slide sideways in the slots or grooves as the linings wear
fixed caliper disc brake
normally uses more than one piston and caliper cylinder. The caliper is bolted directly to the steering knuckle. It is not free to move in relation to the disc. Pistons on both sides of the disc push against the brake pads
runout
wobble on disc brake when using a fixed caliper
brake backing plate
holds the shoes, springs, wheel cylinder, and other parts inside the brake drum, helps keep road dirt and water off the brakes
wheel cylinder
consists of a cylinder or housing, an expander spring, rubber cups, pistons, dust boots, and a bleeder screw
wheel cylinder housing
forms the enclosure for the other parts of the assembly. It has a precision honed cylinder in it for the pistons, the cups, and the spring
wheel cylinder boots
keep road dirt and water out of the cylinder. They snap into grooves on the outside of the housing
wheel cylinder pistons
are metal or plastic plungers that transfer force out of the wheel cylinder assembly. They act on push rods connected to the brake shoes or directly on the shoes
wheel cylinder cups
are rubber seals that keep fluid from leaking past the pistons. They fit in the cylinder and against the pistons
wheel cylinder spring
helps hold the rubber cups against the pistons when the wheel cylinder assembly is not pressurized
cup expanders
sometimes the ends of the wheel cylinder spring have these metal expanders that help press the outer edges of the cups against the wall of the wheel cylinder
drum brake shoe assembloes
brake shoes, rub against the revolving brake drum to produce braking action. Made by fastening friction material onto a metal shoe
primary brake shoe
is the front shoe, it normally has a slightly shorter lining than the secondary shoe
secondary brake shoe
is the rear shoe, it has the largest lining surface area
retracting springs
pull the brake shoes away from the brake drums when the brake pedal is released
hold-down springs
hold the brake shoes against the backing plate when the brakes are in the released position.
brake shoe adjusters
maintain the correct drum-to-lining clearance as the brake linings wear
star wheel
adjusting screw assembly
self-energizing action
when the brake shoes are forced against the rotating drum, they are pulled away from their pivot point by friction, this action draws the shoes tighter against the drum
servo action
results when the primary (front) shoe helps apply the secondary (rear) shoe
stoplight switch
a spring-loaded electrical switch that operates the rear brake lights of the vehicle. The switch is normally open, when the brake pedal is pressed it closes the switch and turns on the brake lights
brake warning light switch/pressure differential valve
warns the driver of a pressure loss on one side of a dual brake system
low-fluid warning light switch
turns on a dash light if the brake fluid in the master cylinder becomes low
metering valve
designed to equalize braking action at each wheel during light brake applications
proportioning valve
is also used to equalize braking action in systems with front disc brakes and rear drum brakes
combination valve
a single unit that functions as a brake warning light switch, a metering valve, and/or a proportioning valve
electronic parking brake
uses the brake system control module to operate an electric servo motor that mechanically engages the rear brakes