By Phillip Holifield and Nick WeilSRJC, Engr 45, Fall 2009 Semester

Disk brakes convert kinetic energy from the car into thermal energy by friction

The brake fluid compresses the piston inside the brake caliper applying pressure to the brake pads

Connected to the axel rotating at the same speed as the wheelGenerally made out of steelCommonly slotted or drilled for extra heat dissipation

Fixed in the brake caliperVarious compounds of materials are usedWear over time and must be replaced

Increase pad and rotor lifeReduce brake noiseCooling to prevent heat fadeMaximize braking forceFederal Safety RequirementsEnvironmental Impact

Passenger Cars:

Low noise and wearTrucks and SUVs:

Heavier weight requires better brakingHigh Performance Cars:

Need maximum braking and cooling

AsbestosSemi-MetallicNon-Asbestos OrganicsLow SteelCarbonExact composition of each manufacturers pads is a closely guarded secret

Widely used in early disk brake applicationsGood for absorbing and dissipating heatAverage stopping powerAsbestos is legally regulate due to its carcinogenic propertiesNo longer used due to health risks

Range from 30% to 65% metal and fillerDifferent pads use Steel, Iron, and CopperHarder material is very durable and has excellent heat resistanceCreates more noise and dustUsed in most cars and SUVs

Low to medium coefficient of friction ~ 0.28 0.38Relatively high mu variation (temperature, duty cycle) Good fade characteristicsPoor wear at low temps.,

Typically contain nonferrous metals, inorganic and organic fibers, abrasives, lubricants and property modifiers such as glass, rubber, kevlar and carbonTypically used in high performance carsAlso referred to as ceramics

Low to medium-high coefficient of friction ~ 0.33 0.40.Excellent wear at lower temps. < 200C.Good for wheel dust. Relatively poor wear under heavy duty conditions and at higher friction levels.Good noise & roughness characteristicsCan have morning effectiveness noise squealing noise on first couple of brake applies in the morningMore expensive.

Typically contain ferrous and nonferrous metals, inorganic and organic fibers, aggressive abrasives, lots of carbonaceous and sulfide lubricantsReplacing semi-metallic as the standard for passenger cars

Higher coefficient of friction levels ~ 0.38 0.50Good pedal feel and braking confidenceGood fade and high speed performanceHigh pad/rotor wearGood for high speed wearLots of wheel dustInferior noise and life.

Composite materials reinforced with carbon fibersUsed for both pads and rotorsUsed in Formula 1 and other race carsMajor manufacturers include Hitco, Brembo and Carbon Industries

Light weight rotors weigh less than 1kgHigh coefficient of friction - can decelerate an F1 car at over 5GOperating temperature is around 800-1000CExtremely expensive to produce

Text:http://en.wikipedia.org/wiki/Brake_padshttp://en.wikipedia.org/wiki/Disk_brakehttp://auto.howstuffworks.com/auto-parts/brakes/brake-types/disc-brake.htmwww.suscon.org/bpp/pdfs/OEBrakePads.pdfhttp://www.performancefriction.com/pages/pad_type.htmhttp://www.f1technical.net/articles/2

Images:http://stmarysjin.org.uk/hsw/gif/disc-brake3.jpghttp://www.akebonobrakes.com/oem/brake_products/images/3d_exploded_caliper.gifhttps://www.nzad.co.nz/store/images/standard%20brake%20rotor%20(Small).jpghttp://www.good-win-racing.com/miata/images/items/GWR-078.jpg