There's a general movement in the automotive industry toward so-called brake-by-wire systems where many of the functions of brakes that have traditionally been performed mechanically will be performed electronically. Hybrids and electric cars will probably be early adopters of these brake types . At present, different automotive engineers have come up with differing circuit designs to handle the complexities of regenerative braking; however, in all cases, the single most important part of the braking circuitry is the braking controller , which we'll discuss in the next section.
Although blended braking combines both dynamic and air braking, the resulting braking force is designed to be the same as what the air brakes on their own provide. This is achieved by maximizing the dynamic brake portion, and automatically regulating the air brake portion, as the main purpose of dynamic braking is to reduce the amount of air braking required. This conserves air, and minimizes the risks of over-heated wheels. One locomotive manufacturer, Electro-Motive Diesel (EMD), estimates that dynamic braking provides between 50% to 70% of the braking force during blended braking.
Cost benefits from the use of regenerative breaking stem from reduced energy costs and lower maintenance costs of the mechanical brakes. The full stop commuter services at Birmingham and Manchester in the UK are for example able to use regenerative braking. With regenerative braking being enabled, their disc brake pad life was around 18 months. When the electric braking was switched off, the pad life reduced to 18 days. (Ford, 2007) As a consequence of less needs for replacement, regenerative breaking also reduces the down-time of the train.