1 - Design a sleeve and cotter joint to resist a tensile load of 60 kN.

All parts of the joint are

ft = 60 N/mm2 ; fs = 70 N/mm2 ; and fc = 125 N/mm2 .

3 - Design a knuckle joint for a tie rod of a circular section to sustain a maximum pull of 70KN.
The ultimate tensile and shear strength of the pin material are 510MPa and 396MPa
respectively. Take factor of safety as 6.
4 - A hand lever has a length of 1100mm from the centre of shaft to the point of application of
400N load. The effective overhang from the nearest bearing is 150mm. If the permissible
tensile stress and shear stress are 73 MPa and 60 MPa respectively. Find:- i) diameter of shaft,
ii) dimensions of boss, iii) section of lever, if t/B = 0.5.
5 - A foot lever is 1mt from centre of shaft to point of application of 800N load. Foot lever is
60mm from the centre of bearing and assume width of arm is 3 times thickness. Permissible
tensile stress may be taken as 73N/mm2 and shear stress as 70N/mm2. Find- :- i) diameter of
shaft, ii) dimensions of boss, iii) dimensions of rectangular cross-section of lever.
6 - A bracket is riveted to a column by 6 rivets of equal size as shown in Fig. It carries a load
of 100 kN at a distance of 250 mm from the column. If the maximum shear stress in the rivet
is limited to 63 N/mm2 , find the diameter of the rivet.

7 - A steel shaft 800 mm long transmitting 15 kW at 400 r.p.m. is supported at two bearings at
the two ends. A gear wheel having 80 teeth and 500 mm pitch circle diameter is mounted at
200 mm from the left hand side bearing and receives power from a pinion meshing with it. The
axis of the pinion and gear lie in the horizontal plane and the tangential force on the gear is
acting vertically downward. A pulley of 300 mm diameter is mounted at 200 mm from the right
hand side bearing and is used for transmitting power by a belt. The belt drive is inclined at 30°
to the vertical (down) in the forward direction. The belt lap angle is 180° and the co-efficient
of friction between the belt and pulley is 0.3. Design and sketch the arrangement of the shaft
assuming the values of safe stresses as: fs = 55 N/mm2 ; ft = 80 N/mm2 . Take torsion and
bending factor as 1.5 and 2.0 respectively. Pressure angle of the gear is 20°. Also assume the
permissible angle of twist is 0.18° / metre length and the modulus of rigidity for the shaft
material is 79300 N/mm2 .

8 - Design and draw a muff coupling which is used to connect two steel shafts transmitting 25
kW power at 360 r.p.m. The shafts and keys are made of plain carbon steel 30C8 ( fyt = fyc =
400 N/mm2 ). The sleeve is made of grey cast iron FG200 ( fut = 200 N/mm2 ). The factor of
safety for the shafts and keys is 4. For sleeve the factor of safety is 6 based on ultimate strength
9 - A protected type flange coupling is used to transmit 15 kW power at 200 r.p.m. The design
torque is 125% of the rated torque. The shafts, keys and bolts are made of plain carbon steel
40C8 (fyt = 380 N/mm2 ) and the factor of safety is 5. The yield strength in compression can
be taken as 150% of the tensile yield strength and the yield strength in shear is 50% as that of
tension. The flanges are made of grey cast iron of grade FG200 (fut = 200 N/mm2 ) and the
factor of safety is 6. The keys have square crosssection. Design the coupling and specify the
dimensions of its parts.

10 - Design and draw a valve spring of a petrol engine for the following operating conditions:
Spring load when the valve is open = 400 N. Spring load when the valve is closed = 250 N.
Maximum inside diameter of the spring = 25 mm. Length of the spring when the valve is open
= 40 mm. Length of the spring when the valve is closed = 50 mm. Maximum permissible shear
stress = 400 N/mm2 . Modulus of rigidity = 80 kN/mm2
11- Design a helical spring for a spring loaded safety valve for the following conditions:
Operating pressure = 1 N/mm2 . Maximum pressure when the valve is blows off freely = 1.075
N/mm2 . Maximum lift of the valve when the pressure is 1.075 N/mm2 = 6 mm. Diameter of
the valve seat = 100 mm. Maximum shear stress = 400 N/mm2 . Modulus of rigidity = 86 ×
103 N/mm2 . Spring index = 5.5.
12 - A vertical two start square threaded screw of a 100 mm mean diameter and 20 mm pitch
supports a vertical load of 18 kN. The axial thrust on the screw is taken by a collar bearing of
250 mm outside diameter and 100 mm inside diameter. Find the force required at the end of a
lever which is 400 mm long in order to lift and lower the load. The coefficient of friction for
the vertical screw and nut is 0.15 and that for collar bearing is 0.20.
13 - The mean diameter of the square threaded screw having pitch of 10 mm is 50 mm. A load
of 20 kN is lifted through a distance of 170 mm. Find the work done in lifting the load and the
efficiency of the screw, when the load rotates with the screw. The external and internal diameter
of the bearing surface of the loose head are 60 mm and 10 mm respectively. The coefficient of
friction for the screw and the bearing surface may be taken as 0.08.
14 - The cross bar of a planner weighing 12 kN is raised and lowered by means of two square
threaded screws of 38 mm outside diameter and 7 mm pitch. The screw is made of steel and a
bronze nut of 38 mm thick. A steel collar has 75 mm outside diameter and 38 mm inside
diameter. The coefficient of friction at the threads is assumed as 0.11 and at the collar 0.13.
Find the force required at a radius of 100 mm to raise and lower the load.
15 - The lead screw of a lathe has Acme threads of 50 mm outside diameter and 8 mm pitch.
The screw must exert an axial pressure of 2500 N in order to drive the tool carriage. The thrust
is carried on a collar 110 mm outside diameter and 55 mm inside diameter and the lead screw
rotates at 30 r.p.m. Determine (a) the power required to drive the screw; and (b) the efficiency
of the lead screw. Assume a coefficient of friction of 0.15 for the screw and 0.12 for the collar.

16 - A power screw having double start square threads of 25 mm nominal diameter and 5 mm
pitch is acted upon by an axial load of 10 kN. The outer and inner diameters of screw collar are
50 mm and 20 mm respectively. The coefficient of thread friction and collar friction may be
assumed as 0.2 and 0.15 respectively. The screw rotates at 12 r.p.m. Assuming uniform wear
condition at the collar and allowable thread bearing pressure of 5.8 N/mm2 , find: (i) the torque
required to rotate the screw; (ii) the stress in the screw; and (iii) the number of threads of nut
in engagement with screw.