Mechanical Braking System 3f3m2g

MECHANICAL BRAKING SYSTEM

Submitted by Regikumar.K 3rd year mechanical

INTRODUCTION Mechanical brakes are assemblies consisting of mechanical elements for the slowing or stopping of shafts in equipment drives.They use levers or linkages to transmit force from one point to another. Braking slows or stops the movement of the coupled shafts.

Brake System Principles  Kinetic Energy  Mass  Weight  Speed  Inertia and Momentum

TYPES OF MECHANICAL BRAKE

 Band brakes  Drum brakes  Disc breaks  . Cone brakes

Band brakes, the simplest brake configuration, have a metal band lined with heat and wear resistant friction material Drum brakes, which are commonly used on automobile rear wheels, work when shoes press against a spinning surface called a drum Disc brakes are constructed of brake pads, a caliper, and a rotor. During operation, the brake pads are squeezed against the rotor Cone brakes are made with a cup and a cone, which is lined with heat and wear resistant material. During actuation,the cone is pressed against the mating cup surface.

MECHANICAL BRAKES

TYPICAL SYSTEM

Disk Brake  It Consists of two Brake pads

 Works similar to Bicycle Brake where two rubber pads rub against the wheel rim.

Disc Brake Parts  Calipers (4)  Brake Pads  Rotors (3)

Disc Brake Operation  A piston inside the caliper pushes the brake pads toward each other  The rotor is located between the pads  The squeezing effect causes friction which slows the car

Disc Brake Problems  Rotor warp from over tightened wheels which causes pedal vibration  Calipers can stick causing the brake pads to drag  Rear wheel disc brake parking brake mechanism can become stuck

HYDRAULIC DISC BRAKES

Disc mech bike

Servicing Disc Brakes  Loosen the caps on the mater cylinder  Use a large screwdriver or pry bar to force the piston back into the caliper  Remove the bolts or clips that hold the caliper to the mounting  Remove the caliper and remove the pads  Check the condition of the rotor, a worn or grooved rotor will need machining

Installing New Disc Brakes      

Put anti-squeal compound on the back of the pads Put new pads into the caliper Install the caliper into the mounting bracket Install the clips or bolts Press on the brake pedal several times until it is firm Check the master cylinder fluid level and tighten caps

Disc Brake Caliper Assembly

Caliper Types There are 2 types of Calipers Fixed  Calipers are disc brakes that use a caliper that is FIXED in position and does not slide. They have pistons on both sides of the disc. There may be 2 or 4 pistons per caliper

Floating  Much more common  Single Piston  Easier to work with  On “inboard” side of caliper

Fixed Caliper  Applies two pistons to opposite sides of rotor  Caliper stays stationary  Disc Brakes require higher hydraulic pressure

Sliding Caliper Applies pressure to two pads on opposite sides of rotor Caliper  Sliding  Fixed

Friction Material exposed to air

Drum Brakes  Expanding shoes create force on the inner surface of the drum  Used on the rear of some trucks and SUV’s  Self-energizing design requires less activation force  Require periodic adjustment

Drum Brake System

Drum Brake Parts  Brake Shoes (5, 12)  Backing Plate (14)  Return Springs (3, 13)  Hold Down Springs (11)  Self Adjusting Parts (4, 7, 8, 10)  Wheel Cylinder  Parking Brake (6, 9)  Drums

Drum Brake Operation  The wheel cylinder forces the brake shoes apart  The shoes are forced against a drum  The friction changes rotary energy into heat energy which slows the car  The harder the shoes are forced apart, the faster the car stops

Drum Brake Problems  Overheating the drums can cause them to warp or over expand (brake fade)  Springs can stretch over time causing the brakes to drag  Wheel cylinders can leak ruining the shoes  Parking brake cables can seize

Servicing Drum Brakes  Using a brake tool, remove the return springs  Remove the hold down springs  Remove the self adjuster rod  Note where the longer brake shoe is located  Remove the parking brake cable  Remove the brake shoes together

Reinstalling Drum Brakes  Transfer all the self adjusting parts to the new shoes  Install on the backing plate  Install the parking brake cable and self adjuster rod  Install the hold down and return springs  Install the drum and adjust till the shoes just hit the drum