SHAFT TERMS

shaft

Is a rotating machine element which is used to transmit power from one place to another.

shaft

Is used for the transmission of torque and bending moment.

shafts

are usually cylindrical, but may be square or cross shaped in section.

shafts

They are solid in cross-section but sometimes hollow shafts are also used.

Line Shaft

Transmission shaft driven by prime mover.

Counter Shaft

Transmission shaft intermediate between the line shaft and the driven machine.

axle

similar in shape to the shaft

axle

is a stationary machine element and is used for the transmission of bending moment only.

spindle

a short shaft that imparts motion either to a cutting tool (e.g. drill press spindles) or to a work piece (e.g. lathe spindles)

TRANSMISSION SHAFTS.

These shafts transmit power between the source and the machines absorbing power.

MACHINE SHAFTS

These shafts form an integral part of the machine itself.

MACHINE SHAFTS

crank shaft is an example of what?

high strength
good machinability.
low notch sensitivity factor.
good heat treatment properties.
high wear resistant properties.

Material Used for Shafts

Shafts

generally manufactured by hot rolling and finished to size by cold drawing or turning and grinding.

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 sizes of transmission shafts are:

Shear stresses

due to the transmission of torque (i.e. due to torsional load).

Bending stresses

(tensile or compressive) due to the forces acting upon machine elements like gears, pulleys etc.

112 MPa for shafts without allowance for keyways.
84 MPa for shafts with allowance for keyways.

Maximum permissible working stresses in tension or compression may be taken as

56 MPa for shafts without allowance for key ways
42 MPa for shafts with allowance for keyways.

Maximum permissible shear stress may be taken as

Strength
Rigidity
Stiffness

The shafts may be designed on the basis of

5m, 6m, and 7m

standard length of the shafts

Shafts subjected to twisting moment or torque only
Shafts subjected to bending moment only
Shafts subjected to combined twisting and bending moments
Shafts subjected to axial loads in addition to combined torsional and bending loads

In designing shafts on the basis of strength, the following cases may be considered