4 Wheel Drive/SUVs: Emergency Brakes in Automobiles.

Question
Dear Carl

http://auto.howstuffworks.com/auto-parts/brakes/brake-types/emergency-brakes.htm

1. Is Emergency Brakes Feature available in all automobiles ?. viz a. two wheeler scooters, motorcycles, bikes etc b. three wheeler viz autorickshaw, tempo c.four wheelers viz Cars, Jeeps, Trucks, Buses, Lorries etc ?.

2. In a rare case technically, the Emergency Brakes can also fail or not work in a automobile for the driver ?.

3. What are the real life situations where emergency brakes can be applied by automobile driver ?.

Thanks & Regards,
Prashant S Akerkar

Answer
Prashant,

In the USA, most vehicles emergency brakes, are now referred to as "parking brakes".  The reason for this, is that they are not reliable for actually stopping a moving vehicle, and there could be a liability from the manufacturer if they were called emergency brakes.

Many vehicles, such as the motorcycles, scooters, etc. have some sort of locking device on one of the tires, so that they are more secure when parked.  This is the same concept for automobiles or trucks.

Most of these brake systems, are nothing more than a cable device that operates the rear brake shoes, or a small pair of shoes in the case of disk brakes.
In an emergency, they can slow a vehicle down, but may not stop it if on a down hill grade, or incline.

Most modern cars have dual master cylinders for the brakes.  One for the front brakes, and one for the rear brakes.  The idea for this, is that if a brake goes out, and fluid is lost, you will still have some emergency braking on one end or another, depending on which end loses fluid.

I hope this helps answer your question.

Carl