Fully considered, since the compressive force the nut is shared between the workpiece and the clamp support inversely as the ratio of their distances form the nut. The distances ‘x’ is less than or equal to but never greater than the distance ‘y’. The spring is fitted with the clamp for its automatic lifting when the nut is loosened to remove the workprice from the jig or fixture. To avoid the complete removal of the nut every time a workpice is changed the clamp may be slotted to draw it back as shown in Fig. 1.23 (b). a two way clamping can be obtained by the bridge clamp as shown in Fig. 1.23(c).