(i) State and describe in brief about four ergonomic considerations in the designing of machine elements.

The different areas covered under the ergonomics are: 1. Communication between the man (user) and the machine. 2. Working environment. 3. Human anatomy and posture while using the machine. 4. Energy expenditure in hand and foot operations. Communication between man and machine  The machine has a display unit and a control unit.  A man (user) receives the information from the machine display through the sense organs.  He (or she) then takes the corrective action on the machine controls using the hands or feet.  This man-machine closed loop system in influenced by the working environmental factors such

as: lighting, noise, temperature, humidity, air circulation, etc. Working Environment  The working environment affects significantly the man-machine relationship.  It affects the efficiency and possibly the health of the operator.  The major working environmental factors are: Lighting, Noise, Temperature, Humidity and air circulation. Ergonomics Considerations in Design of Controls  The control devices should be logically positioned and easily accessible.  The control operation should involve minimum and smooth moments.  The control operation should consume minimum energy.  The controls should be painted in proper colour to attract the attention. Ergonomics Considerations in the Design of Displays  The scale should be clear and legible.  The size of the numbers or letters on the scale should be taken appropriate.  The pointer should have a knife-edge with a mirror in a dial to minimize the parallax error while taking the readings.  The scale should be divided in a linear progression such as 0 – 10 – 20 – 30… and not as 0 – 5 – 25 – 45…..  The number of subdivisions between the numbered divisions should be as less as possible.  The numbering should be in clockwise direction on a circular scale, from left to right on a horizontal scale and from bottom to top on a vertical scale.