| 摘要 |
<p>An output member (15) is positioned by a servo pressure derived from between two variable fluid flow restrictors (18, 19) connected in series between a high pressure (HP) and a low pressure (LP). The flow area of a first restrictor (19) is variable by an input quantity to which the output member (15) is required to respond and the flow area of a second restrictor (18) is varied by movement of said output member (15) to change the servo pressure in a sense to oppose movement of the output member (15). In one embodiment the output member (15) incorporates a control element (20, 22) for the second restrictor (18).</p> |
