The structure and principle of two new types of cutting tools(bevel wedge type and eccentric type)for boring O-ring grooves have been introduced in this paper.

The analysis and control of prism-angle error on seating faces of wedge gate valve;

Replaceable packing with pressure inside screw nonrising stem type wedge gate valve;

Aiming at preventing automatic firing accident of sliding wedge breechblock of ground gun, on the basis of the dint analysis to the percussion mechanism, the disquisition advances and demonstrates the conclusion that seriously abrasion of percussion mechanism is the main cause of automatic firing.