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bolts of uniform strength: if a shank dia.is reduced to a core dia.as shown in fig. the stress become same through out the length of the bolt. Hence impact energy is distributed uniformly throughout the bolt length, thus relieving the threaded portion of high stress. The bolt in this way becomes stronger and lighter. This type of bolt is known as bolt of uniform strength.Another method of obtaining the bolt of uniform strength is shown in fig.in this method, instead of reducing the shank dia.an axial hole is drilled through the head down to

Lewis equation: WT = σw.b.π.m.y, WT= Tangential load acting at the tooth in N σw= bending stress in N/mm2 b= width of the gear face in mm m= module in mm y= lewis form factor.

30 Ni 16 Cr5 : alloy steel carbon 0.3% of average, Nickel 16%, chromium 5% 40C8 : Plain carbon steel carbon 0.4% of average, manganese 0.8% FeE230 : Steel with yield strength of 230N/mm2

X15Cr25Ni12 : high alloy steel carbon 0.15% of average, chromium 25%, Nickel 12%,

Characteristics of Acme thread : (i)thread angle is 290 (ii) permit the use of split nut (iii)easy to manufacture (iv) max. bursting pressure on the thread Characteristics of Square thread : (i) zero profile thread angle (ii) minimum bursting pressure on the nut

Whenever a machine component changes the shape of its cross section, the simple stress distribution no longer holds good. This irregularity in the stress distribution caused by abrupt changes of form is called as stress concentration

Strength equation of double parallel fillet weld= throat area x allowable shear stress P= 2x 0.707x Sw x lwx Ʈ =1.414 x Sw x lwx Ʈ (1mark) Strength equation of single transverse fillet weld

P =throat area x allowable tensile stress P= 0.707x Sw x lw x σ

Rolling contact bearing- contact between the surfaces is rolling ,it is antifriction bearing Advantages (any six) (1)low starting and running friction except at very high speed (2) ability to withstand momentary shock loads (3) accuracy of shaft alignment (4) low cost of maintenance (5) reliability of service (6) easy to mount and erect (7) cleanliness (8) small overall dimension

Horizontal component of 45 KN, WH= 45Sin 600 =45x 0.866=38971N and vertical component of 45 KN, Wv,= 45xcos600 =45x0.5=22500N Direct tensile load in each bolt,Wt1= WH /5=38971/5=7794.20N Turning moment due to WH about G TH = WHx 25=38971x25=974275N (anticlockwise) direct shear load on each bolt =Ws=Wv/5 =22500/5=4500N Turning moment due to Wv about edge of the bracket, Tv= Wvx175=22500x175=3937500N-mm( clockwise( clockwise) Net turning moment =3937500-974275=2963225N---------(I) total moment of the load on the bolts @ th tilting edge = 2w x(L1) 2 + 2w x(L2) 2 =2xwx(50)2 + 2xwx(150)2 = 50000