| 摘要 |
<p>In an operating cycle for a pneumatic operated ramming tool with a compressed-air loaded working piston disposed reciprocally therein, at the beginning of a working stroke the working piston is initially set in motion under the action of small amounts of compressed air until its top moves into a region of stored compressed air which then flows past the sides of the working piston and fully engages the working face thereof for performance of a working stroke. The working cylinder comprises a pressure portion and a guide portion, the upper end of the pressure portion being in communication with the compressed air storage space via a closable control port. Within the pressure portion there is an annular gap between the cylinder wall and the piston and at the bottom end of the pressure portion is a plurality of connecting apertures to the compressed air storage space. The working piston extends into the cylinder pressure portion at its top end carrying two seal rings, and protrudes into the cylinder guide portion at its bottom end carrying one seal ring. The lower one of the two seals fitted at the piston top end serves as return stroke seal due to its variable diameter.</p> |
