Brakes Mechanical Design for Mechanical and Mechatronics Students .pptx

Brake, device for decreasing the speed of a body or for stopping its motion. Most brakes act on rotating mechanical elements and absorb kinetic energy either mechanically, hydrodynamically, or electrically.

Mechanical brakes are the most common; they dissipate kinetic energy in the form of heat generated by mechanical friction between a rotating metallic drum or disk and a stationary friction element brought into contact with it by mechanical, hydraulic, or pneumatic means. The friction elements for drum brakes may be bands or shoes (blocks with one concave surface); for disk brakes they are pads or rings. Friction materials may be organic, metallic, or ceramic; molded asbestos is commonly used.
Mechanical operation by means of rigid links is satisfactory for single brakes, but when several brakes are actuated from a single source, as on an automobile, it is difficult to obtain equal braking effectiveness on all wheels; for this reason, hydraulic actuation, with oil under the same pressure acting on all brakes, is preferable. The braking of railroad cars is effected by cast-iron shoes that bear directly on the circumference of the wheels and are activated by compressed air (see air brake).

A hydrodynamic (fluid) brake has a rotor (rotating element) and a stator (stationary element) that resemble the impeller and runner in a hydraulic coupling. Resistance to rotation is created by fluid friction and circulation of the liquid (usually water) from a series of pockets in the rotor to a series of complementary pockets in the stator. Because the resistance to rotation—i.e., braking power—depends on the speed of the rotor, these brakes cannot completely stop a rotating member; however, if means for cooling the liquid are provided, they can dissipate large amounts of kinetic energy in a very effective manner.
Calorimeter, device for measuring the heat developed during a mechanical, electrical, or chemical reaction and for calculating the heat capacity of materials.

Calorimeters have been designed in great variety. One type in widespread use, called a bomb calorimeter, basically consists of an enclosure in which the reaction takes place, surrounded by a liquid, such as water, that absorbs the heat of the reaction and thus increases in temperature. Measurement of this temperature rise and a knowledge of the weight and heat characteristics of the container and liquid permits the total amount of heat generated to be calculated.
The design of a typical bomb calorimeter is shown in the Figure. The material to be analyzed is deposited inside a steel reaction vessel called a bomb. The steel bomb is placed inside a bucket filled with water, which is kept at a constant temperature relative to the entire calorimeter by use of a heater and a stirrer. The temperature of the water is monitored with a thermometer fitted with a magnifying eyepiece, which allows accurate readings to be taken. he heat released from the sample is largely absorbed by the water

1. Brakes

2. Types of Brakes Hydraulic brakes Electric brakes Mechanical brakes: according to the direction of acting force, may be divided into the following two groups: ( a ) Radial brakes . In these brakes, the force acting on the brake drum is in radial direction. The radial brakes may be sub-divided into external brakes and internal brakes . According to the shape of the friction element, these brakes may be block or shoe brakes and band brakes. ( b ) Axial brakes . In these brakes, the force acting on the brake drum is in axial direction. The axial brakes may be disc brakes and cone brakes. The analysis of these brakes is similar to clutches.

3. Radial Brake

4. External Shoe Brake

5. Internal Shoe Brake

6. Band Brake

7. Disc Brake

8. Design of Single Block or Shoe Brake

9. Design of Single Block or Shoe Brake

10. Design of Single Block or Shoe Brake

11. Design of Pivoted Block or Shoe Brake

12. Design of Double Block or Shoe Brake

13. Design of Simple Band Brake

14. Design of Simple Band Brake