| 摘要 |
A set switch 28 is connected via a first gate 34 to an analog switch 16, a speed incrementing circuit 36, and a latch circuit 30, but is connected directly to a second gate 22. When set switch 28 is actuated, a setting signal is passed through the first gate 34, unless the gate is closed by a signal from an upper-speed limit switch 38, thereby actuating analog switch 16 to pass vehicle speed signals from detector 10 to a storage device 18, and actuating latch circuit 30 to partially enable second gate 22. When set switch 28 is released, analog switch 16 closes, thereby storing the present vehicle speed signal in device 18 as a desired speed signal, and second gate 22 is fully enabled, thereby passing an actual speed/desired speed difference signal from comparator 20 to a speed controller 26. Desired speed can be incremented via circuit 36 by tap-up actuation of set switch 28, but the direct connection of set switch 28 to second gate 22 permits speed retard by actuation of set switch 28 even if the first gate is shut by a signal from upper-speed limit switch 38.
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