THE DYNAMICS OF BRAKING

Gianluca Covini

03 February 2022

What are the basic physical laws that govern a kart while it slows down? Find out in this article, to better understand the behaviour of your vehicle in this crucial phase of driving on a track

WHAT IS IT?

HOW DOES IT WORK?

IN PRACTICE

The braking of a kart is fundamentally based on the braking system, which groups together all the mechanical elements whose task it is to reduce or stop the speed of the vehicle. Since the movement of a kart is obtained by means of the wheels, it is sufficient to apply a braking torque to them to stop the kart. In all karts the braking torque is achieved by the friction generated by the pads on one or more brake discs, depending on what is allowed by the regulations.

The force applied to the pads to generate friction is given by the transformation of the force exerted by the driver with his/her left foot on the pedal, through a kinematic chain and a hydraulic circuit. Since energy is neither created nor destroyed, but transformed, the kinetic energy possessed by the kart in motion is transformed by the braking system into caloric energy that propagates in the air.

BRAKING SYSTEMS FOR SINGLE-SPEED AND SHIFTER KARTS

WHAT IS IT?

HOW DOES IT WORK?

IN PRACTICE

BRAKING FORCE

The braking force is the sum of the individual tangential forces - 2 braking forces for the front wheels (Ta) and 2 braking forces for the rear wheels (Tp) - exchanged on the ground by each wheel: Braking force = 2 x Ta + 2 x Tp For classes where front wheel braking is not possible (OK, OKJ, MINI and more in general in all the single-speed classes), the braking forces will only be those of the rear axle. In practical terms, by tangential we mean that the forces are applied at the point of contact between the wheel and the asphalt and their direction is "horizontal", i.e. parallel to the asphalt.

There are many forces that fall within the study of the deceleration phase of a kart and they are indicated one by one above.
For significant braking, exceeding 0.5 G of deceleration, only the first two contributions have relevant values, while the others can be ignored. The only non-negligible force that opposes braking, in dynamic equilibrium, is therefore the force of inertia. Therefore, the dynamic balance in the braking of a kart relates to the following equation:

Braking force = Inertia force