Shaft

Shaft intro

1. Types
2. Materials
3. Standard sizes
4. Stresses
5. Design stresses

Types:-

 They are mainly classified into two types:

   1: Transmission shafts 

         Transmission shafts are used to transmit power between the source and the machine absorbing power;

       1.1:counter shafts

             

          

           

      1:2: line shafts
       

    2:Machine shafts

      Machine shafts are the integral part of the machine itself;   

    2:1crankshaft
        

       

Materials:-

  1:Mild steel.

  2:Alloy steel.

  3:Nickel-chromium.

  4:Chromium-vanadium steel.

Standard sizes[2]:-

1: Machine shafts

•   Up to 25 mm steps of 0.5 mm
•   25 to 50 mm steps of 1 mm
•   50 to 100 mm steps of 2 mm
•   100 to 200 mm steps of 5 mm

 2:Transmission shafts[edit]

•   25 mm to 60 mm with 5 mm steps
•   60 mm to 110 mm with 10 mm steps
•   110 mm to 140 mm with 15 mm steps
•   140 mm to 500 mm with 20 mm steps

    The standard lengths of the shafts are 5 m, 6 m and 7 m.

Stresses:-

The following stresses are induced in the shafts.

    1:Shear stresses due to the transmission of torque (due to torsional load).

    2:Bending stresses (tensile or compressive) due to the forces acting upon the machine elements like gears and pulleys as well as the self weight of the shaft.
    3:Stresses due to combined torsional and bending loads.

Design stresses:-

The maximum permissible (design) stresses in bending (tension or compression) may be taken as:

    1.    112 N/mm2 for shafts with allowance for keyways.

    2.    84 N/mm2 for shafts without allowance for keyways.

The maximum permissible (design) shear stresses may be taken as:

    1.        56 N/mm2 for shafts with allowance for keyways.

    2.        42 N/mm2 for shafts without allowance for keyways.

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