| 摘要 |
487,422. Actuating controllers. GRAY, W. T., and METROPOLITANVICKERS ELECTRICAL CO., Ltd. Jan. 21, 1937, No. 1843. Addition to 451,514. [Class 38 (iii)] In a system described in the parent Specification there is provided an auxiliary liquid control valve in parallel with the main control valve actuated by an electromagnet controlled by auxiliary contacts on the controller independently of the current limit relay, the auxiliary valve permitting a relatively small flow of liquid to cause a slow movement of the controller. The auxiliary contacts are disposed in relation to the contacts controlling the main control valve so that the auxiliary valve is opened when the controller is positioned in one or more sections between the main control positions but is closed at the actual control positions. Thus if the limit switch operates with the controller in a section having auxiliary contacts, the controller is moved slowly to the adjacent control position whereupon it is stopped until reclosure of the limit switch. The circuit through auxiliary contacts may be opened at one or more intermediate positions in a section so that the slow movement of the controller may be arrested at an intermediate position. The auxiliary valve may byepass the main control valve only or both the valve and the restriction through which the main control valve supplies the liquid pressure. |
