| 摘要 |
<p>A gravity operated gate opener is provided comprising a main operating member (12) having two terminal positions namely a first terminal position corresponding to a closed condition of a gate (2) associated therewith and a second terminal position corresponding to an open condition of the gate. Gravity operated means that include two tread plates (1), one on each side of the gate, operatively move the main operating member from the first terminal position to the second terminal position in which it is biased towards said first terminal position. Latch means (36) hold the main operating member in said second terminal position until the latch means is released. An indexing assembly includes an indexing element (33) movable incrementally in one direction in response to each operation of the tread plate on one side of the gate and in an opposite direction in response to each operation of the tread plate on the other side of the gate. The indexing assembly is configured to obstruct release of said latch means until the number of incremental movements of the indexing element in one direction is equal to the number of incremental movements of the indexing element in the opposite direction and thereby preventing the gate from closing until all of the vehicle wheels have passed over both of the tread plates.</p> |
