Gravity Control - Engineering Notes

Gravity Control

This type of control consists of a small weight attached to the moving system whose position is adjustable. This weight produces a controlling torque due to gravity. This weight is called control weight. The control system is as shown in the figure. At the zero position of the pointer, the controlling torque is zero. The control weights acts at a distance  'l' from the center. 

Gravity Control

Advantages of Gravity Control:

1. The performance is not time dependent.
2. It is simple and cheap.
3. Controlling torque can be varied by adjusting the position of the control weight.
4. The performance is not temperature dependent.

Disadvantages of Gravity Control:

1. Scale is non uniform. So readings are not accurate.
2. The system is used in vertical position only and must be properly levelled. Otherwise it may cause serious errors in the measurements.
3. As delicate and proper levelling required, in general it is not used for indicating instruments and portable instruments.