| 摘要 |
Automatic door closers have a latch mechanism for holding the door open. In one mode of operation, the latching of the door is effected automatically when the door is opened. Tapping the door closer cylinder upwardly releases the latch mechanism and allows the door to close. Manual manipulation of the latch mechanism is required to latch the door open in a second mode of operation. However, in this mode of operation, the latch mechanism can be released simply by opening the door slightly beyond its latched position. The door closer includes a cylinder with a rectilinearly displaceable piston rod housed therein and extending through one cylinder head; and the latch mechanism comprises that cylinder head and a notch in the piston rod into which cylinder head is fitted to keep the piston rod from telescoping into the cylinder. The opposite end of the cylinder and the exposed end of the piston rod are attached to the door and the door frame. Consequently, the door cannot close as long as the piston rod is kept from telescoping into the cylinder by the latch mechanism.
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