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Braking distance refers to the distance a vehicle will travel from the point when its brakes are fully applied to when it comes to a complete stop. It is primarily affected by the original speed of the vehicle and the coefficient of friction between the tires and the road surface, [Note 1] and negligibly by the tires' rolling resistance and vehicle's air drag.
Thus, we can find the brake force of a vehicle through the formula: [1] = where: is the brake force; is the mass of the vehicle; is the initial velocity of the vehicle when the brakes were applied; is the distance traveled by the vehicle between when the brakes were applied until coming to a stop
d MT = braking distance, m (ft) V = design speed, km/h (mph) a = deceleration rate, m/s 2 (ft/s 2) Actual braking distances are affected by the vehicle type and condition, the incline of the road, the available traction, and numerous other factors. A deceleration rate of 3.4 m/s 2 (11.2 ft/s 2) is used to determine stopping sight distance. [6]
Since kinetic energy increases quadratically with velocity (= /), an object moving at 10 m/s has 100 times as much energy as one of the same mass moving at 1 m/s, and consequently the theoretical braking distance, when braking at the traction limit, is up to 100 times as long. In practice, fast vehicles usually have significant air drag, and ...
Braking system Train speed Distance Stopping time (s) mph km/h yd m Continuous (vacuum) 45 72: 410 370 26 Continuous (vacuum) 45 72: 451 412 30 3 brake vans: 40.9 65.8: 800 730 59 2 brake vans: 40.9 65.8: 631 577 44 2 brake vans: 45 72: 795 727 55 1 brake van: 45 72: 1,125 1,029 70
In some cases, the brake balance may be adjusted to match the traction (grip) of the vehicle during braking, which usually means distributing a greater braking force to the front (for example 55/45). In other cases, it may be desirable for the brake balance to be the more similar at the front and rear (e.g. 50/50) for the tires to last longer ...
Threshold braking or limit braking is a driving technique most commonly used not only in motor racing, but also practiced in road vehicles to slow a vehicle at the maximum rate using the brakes. [1] The technique involves the driver controlling the brake pedal (or lever) pressure to maximize the braking force developed by the tires .
Various brake designs such as band brakes and many drum brakes are self-assisting: when the brake is applied, some of the braking force feeds back into the brake mechanism to further self-apply the brake. This is called "positive feedback" or "self-servo". Self-assist reduces the input force needed to apply the brake, but exaggerates fade ...