| 摘要 |
<p>A control system for extending and retracting a spreader having a base section and a pair of extensible sections includes a hydraulic circuit for supplying pressurized fluid to fluid rams to extend and retract the sections with an electric control circuit for actuating a control valve. The electric control circuit includes a manual switch having extend and retract positions energizing extend and retract solenoids on the valve. The electric circuit also includes holding means for maintaining either solenoid energized and position control means for automatically de-energizing either solenoid when the sections reach a predetermined position with respect to each other. A single two-position switch is utilized as the position control means cooperates with the hydraulic circuit which locks the spreader sections in predetermined position with respect to each other. These predetermined positions are defined by an elongated rod having detents spaced thereon and secured to one extensible section with an electrical cable surrounding the rod and extending to the outer end of the extensible section to define the electrical connections between the switches on the extensible sections and the remainder of the electrical circuit and the hydraulic circuit on the base section.</p> |
