design of couplings(basics)

MUFF COUPLING:

Design procedure

1.          Calculate the diameter of each shaft by following equations

                  Or          

2.          Calculate the dimensions of sleeve by following equations.

             D = 2d + 13

             L = 3.5 d

             also check the torsional shear stress

            

            

            

3.          Determine the standard cross section of flat key from Data book.

            

            

            

             Shafts and keys are made of plain carbon steel.  The sleeve is usually made of grey cast iron of grade FG 200.

CLAMP COUPLING

1.          Calculate the diameter of each shaft by following eqn.

                  

2.          Calculate the main dimensions of sleeve halves;

             D = 2.5 d, L = 3.5 d

3.          Determine standard cross section of flat key.

            

            

4.          Calculate the diameter of clamping bolt

              and

FLANGE COUPLING

1.          Shaft Diameter: Calculate the shaft diameter using following equations.

                 

2.          Dimensions of Flange.

             d_h = 2d, lh = 1.5 d, D = 3d, t = 0.5 d, t₁ = 0.5 d, t₁ = 0.25 d, dr = 1.5 d,
D₀ = (4d + 2t₁)

             Torsional shear stress in hub can be calculated by considering it as hollow shaft subjected to torsional moment M_t.

                            

The flange at the jun. of hub is under shear while transmitting the torsional moment M_t.

            

3.          Diameter of Bolts:

             N = 3 for d < 40

             N = 40 for 40  d < 100 mm

             N = 6 for 100  d < 180 mm

            

4.          Dimensions of key:

             Standard dimensions of key can be obtained from table 4.1 Data book.  The length of key in each shaft is l_h.

            

            

            

FLEXIBLE COUPLING

1.          Shaft diameter: Calculate shaft dia. by using following equation.

                  

2.          Dimensions of flanges: Calculate dimensions of flanges by following empirical equations.

             d_h = 2d, lh = 1.5 d, D = 3d to 4d, t = 0.5 d, t₁ = 0.25 d

             The torsional shear stress in the hub can be calculated by considering it as hollow shaft subjected to torsional moment M_t.

                               

3.          Diameter of pins:

             The number of pins is usually 4 or 6.  The diameter of pins is calculated by

            

             Determine the shear stress

            

4.          Dimensions of pins: Calculate the outer diameter of the rubber bush.

            

             l_b = D_b.

5.          Dimensions of the key

             l = l_n

            

            

References

1.      Mechanical Engineering Design – Joseph Shigley

2.      Machine Design – Mubeen

3.      Machine Design – Black
4.      Principles of Lubrication – Cameron A.