| 摘要 |
<p>In self-propelled reversible boring ram, selection of forward/reverse boring modes is determined by the position of a control piston (3). A concentric supply pipe to a source of working fluid pressure is connected to coaxial fluid inputs (9, 10). Working fluid pressure for an impacting piston (2) (hammer) is supplied through the input (10). For forward mode operation pressure from a coil spring (7) and reactive force on the piston (3) is overcome by working fluid pressure on servo pistons (5, 6 and 8). Restricting fluid pressure on the pistons (5 and 6) allows the piston (3) to move to reverse mode operating position.</p> |
