<Li> Drag--Brakes have varied amount of drag in the off - brake condition depending on design of the system to accommodate total system compliance and deformation that exists under braking with ability to retract friction material from the rubbing surface in the off - brake condition . </Li> <Li> Durability--Friction brakes have wear surfaces that must be renewed periodically . Wear surfaces include the brake shoes or pads, and also the brake disc or drum . There may be tradeoffs, for example a wear surface that generates high peak force may also wear quickly . </Li> <Li> Weight--Brakes are often "added weight" in that they serve no other function . Further, brakes are often mounted on wheels, and unsprung weight can significantly hurt traction in some circumstances . "Weight" may mean the brake itself, or may include additional support structure . </Li> <Li> Noise--Brakes usually create some minor noise when applied, but often create squeal or grinding noises that are quite loud . </Li>

The braking system on a car is an example of