Class Room

DESIGN PROCEDURE OF COTTER JOINT Cotter Joint Introduction  Before going into detailed steps to design and find dimensions of cotter joint, it is necessary to understand clearly the various components, their functions and assembly of cotter joint. Here is the exploded view of cotter joint. Exploded View of Cotter joint assembly Spigot is the male part of the joint , it has a rectangular slot for passing the cotter through it. Spigot  has a collar which rests against the socket end. Socket is the female part of the joint, it also has a rectangular slot for passing the cotter through it. It has a circular hole in which spigot fits. Cotter is a wedge shaped piece of metal which actually connects two parts which are non rotating. Cotter is fitted in the slot and remains in its position by wedge action. Taper is provided to, i) With taper it is easy to remove the cotter and dismantle the joint ii) It ensures tightness of the joint in operation and prevents loosening of

Babcock and Wilcox boiler:       The  Babcock and Wilcox boiler  are also is known as  Longitudinal Drum Boiler or Horizontal Tubes Boiler . It is probably the first water tube boiler designed and widely used across the globe. A schematic of the Babcock and Wilcox boiler is shown in figure.   Construction : • A horizontal steam and water drum : T his is the main part of the boiler. It is supported by a steel structure at a certain height and is independent of brickworks. The size of the boiler drum is small as compared with the boiler drum of a fire-tube boiler of the same capacity. It has water and steam. All safety and control devices are mounted on the boiler drum. • A bundle of steel tubes : T he front end of the boiler drum is connected to the uptake header (water box) by a short tube and the rear end is connected to the down take header (water box) by a long tube. In between the headers, a number of small-diameter steel tubes are fitted at an angle of 5° to 15°

The boiler mountings and accessories that are installed on the steam boiler are as follows q  Boiler Mountings 1. Water level indicator ( Water level gauge) 2. Pressure gauge 3. Safety valves 4. Stop valve 5. Blow off Valve 6. Feed check valve q  Boiler Accessories 1. Air pre-heater 2. Super heater 3. Economiser 4. Feed pump The function of various boiler mountings and accessories are : Boiler Mounting:  Boiler mountings are the safety devices which are fitted on the boiler for its safe and efficient working. 1. Water Level Indicator    • It is fitted in front of the boiler and generally present two in number.    • It is used to indicate the water level inside the boiler. It shows the instantaneous level of water that is present inside the steam boiler which is necessary for its proper working. 2. Pressure gauge    • It is also present in front of the boiler.    • It is used to measure the pressure of the steam inside the boiler.

Summary of Design Procedure(Knuckle Joint) in Tabular form NUMERICAL PROBLEMS   1) It is required to design a Knuckle joint to connect two circular rods which are subjected to an axial tensile load of 50 kN. the material used for joints is 50c8, having  yield point stress 400 N/mm2. taking factor of safety as 5, find the all dimensions of Knuckle joint. 2) A Knuckle joint carries  an axial load of 100 kN.  it connects two circular rods which are made up of material 40c8, having  yield strength 360 N/mm2.  using factor of safety 4 design and draw the Knuckle joint.  Show all important dimensions in the final drawing. 3) Design a Knuckle joint to transmit a load of 50 kN, assume permissible stresses as 40 N/mm 2 in 10 size 40 N/mm 2 in shear and 80 N/mm 2 in compression.Also draw neat dimensioned sketch of Knuckle joint showing all important dimensions designed. 4) designer Knuckle joint subjected to a pull of 30000N.  assume permissible