1. Keys and Coupling
Many Types of Keys and couplings, however understand how Torque is transferred in between each, and forms shearing stresses

2. Shaft Coupling Sometimes, join 2 shafts together Flanged couplings
Torque in Shaft  Torque in Couplings  Shear in bolts
Similarly keys
Bolt circle
Flanged Couplings
Bolt
Shaft

3. TA < TR Design of Shaft Torque applied, TA = ∏ τ d3 / 16
Where, τ = shear stress in shaft d = shaft dia.
Design of bolts Torque resisted,
TR = Shear Stress Area x Radius of bolt circle
TR = n . (∏/4) . db2 . τ b . (D/2)
Where, τ b = shear stress in bolt db = bolt dia.
D = Diameter of bolt circle
n = number of bolts
TA < TR

4. TA < Tk Design of Shaft Torque applied, TA = ∏ τ d3 / 16
Where, τ = shear stress in shaft d = shaft dia.
Design of keys
Torque resisted,
Tk = Shear Stress Area x Radius of shaft
Tk = l b τ k (D/2)
Where, τ k = shear stress in key db = bolt dia.
D = Diameter of bolt circle
n = number of bolts
TA < Tk .

5. Springs and Stiffness
Stiffness of spring Load required to produce a unit deflection in spring. K = F/x x=unit deflection Under gravity, W = F

6. Springs Types of spring Bending / leaf / laminated spring
Torsion / helical spring
Close Coil helical spring
Open Coil helical spring

7. Springs Uses of Springs Storing energy, used in watch Shock absorbers
Seismic isolation
Spring balance
Cycle seats

8. Closed Coiled helical springs subjected to axial loads
R = radius of the coil
d = Spring wire diameter
W= axial load on spring
N = number of coils/turns
δ = deflection
τ, θ, G,
Torque produced by axial load
T = W R
Also T = ∏ τ d3/16
Thus, ∏ τ d3/16 = W R

9. Length of wire = no. of coils x length of one coil Or, l = n 2∏R T = G θ J l θ = 64 WR2 n Gd4 δ = R. θ = 64 WR3 n Stiffness, s = W = Gd4 δ 64 R3 n Energy Stored in a spring, U = (1/2) W δ

10. Combined Bending and Torsion
Find how Tanθ = 2 τ / f = T /M
Where
T = Torsion,
M = Bending Moment
τ = Shear Stress
M = Bending Stress

11. Tutorial- 2 Sketch 5 examples of use of springs
List differences between closed and open coil springs. Provide one sketch minimum
Answer Q.1. from Rethalia’s exercise on Helical Springs. pp. 72
Answer Q.1. to Q.7 from Rethalia’s example exercise