Disc Brakes Vs Drum Brakes

hi Sharma Sir,

Could you pls tell me the difference between Disc brakes and Drum brakes ?

all i know abt them is that Disc brakes are better than Drumb brakes.... but whats the reason behind it ??...

Hi banwari Sir..... do reply to my question...... waiting.....

Karan,

Let me explain Drum vs Disc brakes in brief.

Drum Brakes have drum-kind, hollow structure (example, front brake of any 100cc bike in country) which has shoes inside. When you brake these shoes stick to drum's inside body. This friction between the two bodies does nothing but energy conversion i.e. kinetic energy converts into heat energy. Though brake-shoes and drum are capable of absorbing the heat in normal braking conditions, but they fail when you brake too hard or at higher speeds. This causes more heat to be produced than to be consumed by the shoe material. As a result brakes become ineffective.

Disc brakes have a disc (in place of drum) which has larger surface area than drum (normally). There are two brakes which stick to disc when brake-pedal is pressed. This produces heat again but since disc is exposed to air, disc cools off almost instantly thus making the braking much effective.

As you can see, disc brakes are more effective than drum brakes in normal and weired braking conditions.



Lots of new features in Forum! Check out Announcements section. :~)

alrite .... thanx Banwari sir.... and what about cars ??.... one more thing.... remember the brakes of cars till 97-98 ?...(or maybe a yr or two more) they used to be alot harder than the brakes used today ??....what exactly is the funda with these new brakes ??..and also with these new brakes...try braking when the car is off.....after peddling once or twice... one can feel the brake peddle getting harder...... y is that ?...

Mr. Gambhir,

The problem that you have mentioned is due to the entrapment of atmospheric air in the braking system of the concerned vehicle.  Any vehicle after undergoing a braking system overhaul / repair has air in its system.  If this air is not bled off before driving the car then the pedal becomes spongy and braking action is impaired. This is because  liquids are incompressible while gases can be compressed.  This situation can also arise in case there is a minor leak in the system and the brake oil reservoir becomes empty allowing air to enter into the system.  To solve thiis problem please ensure your brake oil reservoir is maintained full by checking it everyday.  Any drop in level should be investigated to and attended to immediately.  Get your brakes bled by a reputed car mechanic wheel by wheel.  Remember for vehicles equipped with a vacuum servo assisted system this operation should always be done with the vehicle's engine idling.  After the operation your brake pedal should be totally free of any trace of sponginess and the brakes should act instantaneously without the vehicle pulling to one side while driving.  Good working brakes are essential for the safety of all motorists and other road users.

Hi Mr Alam, thanx 4 ur reply and ur concern, but i guess u mis-interpretted my question a little bit..... reagrding these brakes.... try doing that with your own car too....when ur car is off,press the pedal 2-3 times and u'll notice ur brake pedal will get tighter....this happens in EVERY car.... regardles of ne modification/overhauling... and what exactly is "Vacuum Servo" ??.. cheers...

no replies yet ???...

 

bharath here..

am i right??

about the vacuum servo issue... the engine when in idling (starts sucking air ) from the atmosphere... this creates a vacuum in the inlet manifold of the engine and to remove that vaccum this brake vaccum booster is there..

this vacuum booster also multiplies the pedal effort in braking.... suppose 5kg of force is applied, due to lever ratio the force is multiplied and vacuum boost also multipies the force resukting in a high pressure (hydraulic)... the booster is connected inbetween the master cylinder and the brake pedal...

i agree to your comments. Disc is always effective when its dry. However disc brakes come useless when its raining. And moreover as the disc's are exposed to air it gets wet and does not conduct properly. The best way is ceramic disc's they are the best ones..