| 摘要 |
<p>A motor piston (18) is caused to reciprocate in a motor cylinder (12) by compressed air fed to alternate sides of the cylinder (12), under the control of a valve (32). A control piston (20;22) is linked to the motor piston (18) for movement in a control cylinder (14;16). As it moves towards one end, it expels air from the cylinder (14;16) through an outlet (38). For the last part of the stroke, the outlet (38) is closed off by the piston (20;22), so air pressure rises. This pressure is conveyed (40) to the valve (32), and causes it to switch, thus causing the pistons (18,20,22) to be driven the other way. <IMAGE></p> |
