| 摘要 |
<p>A door closer and holder comprises a cylinder shell having a piston sealingly reciprocable therein. A spring biases the piston toward one end of the shell, and the piston is connected through the ususal apparatus to the door. At the one end the operating rod of a shuttle valve extends into the shell and is engaged by the piston as it approaches the end. The shuttle valve selectively directs the return fluid flow through sweep- and latch-control valves. The assembly also includes a solenoid-operated "bullet" which closes off the return flow to hold the door open. The angle of the openness at which the door is held may be selected by setting a cam on the holder drive pinion which engages a switch to activate the solenoid.</p> |
