| 摘要 |
<p>A brake source select system for selecting one of a plurality of sources of pressurized hydraulic fluid for use in actuating a brake system. The brake source select system (10) includes a primary, secondary and reserve source (20, 22 and 24) of pressurized hydraulic fluid connected in fluid communication respectively to a primary selector valve (32), a secondary selector valve (96) and a reserve selector valve (102). Pressurized hydraulic fluid from the primary source (20) is applied to deselect ports (94 and 100) on the secondary and reserve selector valves, causing those valves to block fluid flow from their associated sources to the brake system, so long as the primary source is operative. Upon failure of the primary source, pressurized fluid is no longer applied to the deselect port of the secondary selector valve, thereby enabling fluid flow through the valve, and causing pressurized hydraulic fluid from the secondary source to be applied to the deselect port (160) of the reserve selector valve and to a deselect port (164) of the primary selector valve, effectively blocking fluid flow through each of those valves. Should the secondary source fail, elimination of the pressurized fluid applied to the deselect port of the reserve selector valve enables it to conduct pressurized hydraulic fluid to the brake system, and applies the pressurized hydraulic fluid to the primary and secondary selector valve deselect ports, blocking fluid flow through those valves. Thus, failure of a higher priority source automatically results in selection of a next lower priority source to provide pressurized fluid to the brake system. In addition, a source of pressurized fluid associated with retraction of a landing gear is applied to a selection port (208) of the secondary selector valve, causing that valve to provide a source of pressurized hydraulic fluid to actuate the brakes, slowing the rotation of wheels prior to full retraction of the landing gear.</p> |
