DESIGN OF TURNING LEVER

Select a material for the turning lever (low carbon hot rolled steel, say between AISI HR 1010 to HR 1020 from Table E-20).

Calculate starting torque.

Starting torque, .

Estimate human force applied transversely to move the lever, say between 250 N to 300 N.

Calculate length of the turning lever, .

The head is provided with two holes at right angles to receive the handle for rotating the screw.

The diameter of the head on the top of the screwed rod is usually taken as 1.75 - 2 times the outside diameter of the screw .

.

The height of head is usually taken as twice the diameter of the handle,

.

Moment arm

, where and

Use Von Mises (DE) equation to calculate .

Calculate factor of safety , .

DESIGN OF CUP

The cup prevents the load from rotating.

The cup is fitted with a pin of diameter , .

This pin remains a loose fit in the cup.

Other dimensions for the cup may be taken as follows :

Height of Cup = .

Thickness of Cup .

Diameter at the bottom of the Cup .

Diameter at the top of the Cup .

Thickness of the collar

Calculate thickness of the collar

Shear stress:

Bearing stress:

Solve for tc using the maximum shear stress theory

DESIGN OF RETAINING PIN

Select a standard dowel pin from the Table 22-7 (Standard Handbook of Machine Design, Shigley, Chapter 22, page 22.11).