Sensing Brake Pad Wear Modern Sensors Can Estimate Mileage Until Brake Pads Wear Out

摘要

On most Asian imports and domestic vehicles,the brake pad wear sensor was merely a piece of bent sheet metal that would make contact with the rotor when the brake pad was worn past minimum specifications.It works only if the”squealer”can stay on the brake pad and if the driver knows what the squealing means.But with today's well-insulated vehicles and air conditioning,the driver does not notice anything is wrong until grinding and pedal feedback are present.Turning to luxury European vehicles,most owners do not want to find out they need new brake pads because of obnoxious grinding.On most high-end German imports,the brake pad wear sensors alert the driver with a light and warning on the dash.These vehicles use a loop of wire embedded in the friction material.The loop is set in the last 3 mm to 5 mm of pad material or the sensor is set in plastic and attached to the backing plate.When the pads wear down it causes the loop to break.This triggers a change in resistance that causes the warning.Brake pad wear sensors have been around for more than 40 years,but in the past decade they have evolved so that brake wear can be estimated.This has allowed drivers to pick the right time to have their brake pads replaced.Old School Most older brake pad wear systems had a sensor at each corner of the vehicle on the inboard pad.These systems can vary in the number of wheels that have sensors and where the placement is on the pads.Since the 1970s,they have been just a loop of wire with a small amount of current running through them.