Hydraulic safety barrier traffic-way controller

Claim 1

A self contained vehicle traffic-way controller of retractile barrier configuration subject to upward and downward impacts and wherein actuation and control is by instantly reversible hydraulics, and including; a barrier disposed across a traffic-way and pivoted to a frame for extension through intermediate positions to an UP position projecting as an abutment exposed to impact in the traffic-way and to a DOWN position substantially coplanar with the traffic-way, at least one double acting cylinder and piston actuator connected between the barrier and frame and operable between a normally extended UP position of the barrier and a retracted DOWN position of the barrier, an intermittent running motor driven pump means supplying fluid from a reservoir at a variable pressure and a volume rate complementary to the time-demand requirement of said at least one cylinder and piston actuator, a pressure-volume accumulator open into a supply line from the motor driven pump means and storing potential energy as fluid volume under low to high pressure, an instantly reversible valve means in a supply line between the pressure-volume accumulator and the cylinder and piston actuator and having two controlled operating positions, an UP position pressuring a lower end and exhausting an upper end of the actuator and extending said actuator, and a DOWN position pressuring the upper end and exhausting the lower end of the actuator and retracting said actuator, a high-low pressure switch open to and responsive to accumulator pressure to close an energizing circuit to the motor at a predetermined low accumulator pressure and to open the energizing circuit at a predetermined high accumulator pressure thereby maintaining a variable pressure and proportionate volume of fluid in the accumulator, a check valve in and preventing reverse flow in the supply line between the motor driven pump means and the pressure-volume accumulator to hold a fluid volume in the accumulator for yielding to retraction of the actuator when moving and when held to said UP position to protect both the actuator and pump and related structure from hydraulic impact, and control means switching the valve means alternately into said UP and DOWN positions.