| 摘要 |
In order to save physical power and avoid using manual operative mechanism for unload/reload ladders from/onto a vehicle roof, a electric motor driven ladder rack system has been designed which includes: a fixed guide which is mounted on a vehicle roof; a pivotal guide that is pivotally coupled to the fixed guide; a driving box and a sliding ladder rack which is linked to the driving box by chain and engaged with the pivotal guide. Under acting force of motor and gravity the ladder rack moves sliding backward and pivoting downward from the horizontal position on the vehicle roof to a generally vertical position behind the vehicle at which the ladders can be unloaded/loaded. In an opposite process the ladder rack is pulled back on the vehicle roof. In these processes there is no physical power needed at all.
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