TOPIC: BRAKE
WEEKLY PRESENTATION NO: 2
CONTENTS:• Basics • Single block brake• Double block brake• Pivoted block brake• Self energizing and self locking brakes• Problem• solution
BASICS FOR BLOCK/SHOE BRAKE:
l = pivot to force applied distancex = wheel center to pivot distanceFt = Tangential forceRn = Normal reaction2θ = Angle of contacta = Ofsett distance
2𝜃
SINGLE BLOCK DOUBLE:• SINGLE BLOCK IS USED• MATERIAL• APPLICATION1. TRAM2. TRAIN
DOUBLE BLOCK BRAKE• 2 BLOCK OR SHOE ARE USED• OVERCOMES DRAWBACK OF SINGLE ONE• APPLICATION1. ELECTRIC CRANES2. CYCLES
PIVOTED BLOCK BRAKE• BLOCK IS PIVOTED • ANGLE OF CONTACT MORE THAN 60degree
SELF LOCKING & SELF ENERGISING
𝐴=𝜋 𝑟2
Self-locking brakes self-energizing brakex ≤ μ.a & P=0 vs P≠0
PROBLEM:• Given conditions: Eric’s weight as 80kg and weight of cycle
as 10kg, driving speed is 20km/hr on a level road and front wheel diameter is 0.75m. Pressure applied on brake is 150N with coefficient of friction 0.6.
• To find: 1. distance travelled after application of brake?2. No of revolution made?
SOLUTION:• Velocity = 5.56 m/sec• Total mass = 90kg• Work done against friction= K.I energy of bicycle• frictional force X distance= K.I energy of bicycle
Stopping distance = 15.44m
SOLUTION Part 2:• Distance travelled in one turn = circumference of wheel
• Circumference = 2.3561m• N N
REFRENCES:• https://upload.wikimedia.org/wikipedia/commons/1/1b/Labeled_brake
_set_mono_2.jpg
• http://i.ytimg.com/vi/JHBlIsmWPYA/maxresdefault.jpg• https://upload.wikimedia.org/wikipedia/commons/thumb/1/1b/Labele
d_brake_set_mono_2.jpg/400px-Labeled_brake_set_mono_2.jpg• http://eorailway.co.uk/departments/diary/uploaded_images/Mk2-TSO-
Replaced-Brake-shoes-22_Nov_2012.jpg• http://thumbs.dreamstime.com/x/train-brake-11494344.jpg• http://www.railway-technical.com/Brake-Discs.jpg• https://upload.wikimedia.org/wikipedia/commons/8/80/Bicycle_calipe
r_brake_highlighted.jpg• https://upload.wikimedia.org/wikipedia/commons/8/8d/Bicycle_brake
s_-_animated.gif• http://www.railway-technical.com/airbra-app.gif• TECH MAX publication book on “ THEORY OF MACHINE 2”
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