As Garry pointed out, there are generally 2 mechanisms on a baitcaster that control the cast - the tension knob and then the other braking system.
The tension knob applies axial force onto the tip of the spool pin. The friction must be overcome by the cast to get the spool turning. Additionally, the friction serves to bring the spinning spool to a stop. Most reels are equipped with this (I only say most because I have never seen one without, but cannot say for sure).
The "other" braking system is what is usually advertised with the reel - magnetic, centrifugal, or dual.
Centrifugal brakes are usually small brake tabs installed radially along the spool. These tabs, as the spool begins to spin, move outwards along their tracks (from the centrifugal force of the spool's spin) and contact an outer race. The friction between the tabs and the outer race is what results int he braking force of this system. The braking force for this system is proportional to the spool speed. In other words, the braking force increases as the spool speed increases. So, at low speeds, very little braking force is applied, and at higher speeds, more force is applied, slowing the spool spin even moreso at higher spool speeds. This can theoretically minimize maximum casting distance by the application of too much force at the spool's top speeds. This braking system works well for slow spool speed techniques such as flipping and pitching.
Magnetic brakes are comprised of magnets that are adjusted to different distances from a cup attached to the spool. The distance between the magnets and the cup creates a magentic force that resists the spinning of the spool. The braking force is constant and is applied evenly throughout a cast - from beginning to end. This can limit the distance of casts by applying too much braking force at the end of casts when the spool naturally spins slower. It can also limit the distance on slow spool speed techniques such as pitching and flipping.
Daiwa's Magforce V and Z systems differ from the normal magnetic braking systems in that the cup is installed along a track that extends outwards towards the magnets as the spool spins faster, and retracts at slower spool speeds. Effectively, this minimizes the braking force at the beginning of casts - similarly to centrifugal brakes, while also minimizing the braking at top spool speeds. It is Daiwa's attempt to get the best of both worlds.
Dual braking systems have in fact, included both worlds.
PainInTheBass
