Mechanical Engg Simple Notes ,Solved problems and Videos

When a section is subjected to two equal and opposite forces acting tangentially across the section such that it tends to shear off across the section. The stress produces is called as transverse shear stress. …………………… From figure Mathematically transverse shear stress is represented as, τ = / Where, F = Tangential force applied A = Area of cross section = ( /4 ) 2 d = Diameter of rivet.

1. Bending failure. 2. Pitting. 3. Scoring. 4. Abrasive wear. 5. Corrosive wear Remedies to avoid failure: 1. Bending failure. In order to avoid such failure, the module and face width of the gear is adjusted so that the beam strength is greater than the dynamic load. 2. Pitting. In order to avoid the pitting, the dynamic load between the gear tooth should be less than the wear strength of the gear tooth. 3. Scoring.

The keyway is a slot machined either on the shaft or in hub to accommodate the key. It is cut by vertical or horizontal milling cutter. A little consideration will show that the keyway cut into the shaft reduces the load carrying capacity of the shaft. This is due to the stress concentration near the corners of the keyway and reduction in the crosssectional area of the shaft. It other words, the torsional strength of the shaft is reduced. The following relation for the weakening effect of the keyway is based on the experimental results by H.F. Moore.

1) Red: Danger,Hot 2) Orange: Possible Orange 3) Green : Safe 4) Blue: Cold

Keys are classified on the basis of shape and application of keys.………………are 1) Sunk Key : a) Rectangular sunk key b) square sunk key c) Gib head key d) feather key e) Woodruff key 2) Saddle key a) Flat saddle key b) hollow saddle key 3) Round key 4) Splines …………………: 1) Sunk Key : used for heavy duty application a) Rectangular sunk key : for preventing rotation of gears and pulleys on shaft b) Gib headed key: used where key to be removed frequently.