Bomb truck barrier - GIF

[Frank S]

When I was in the Middle East we made a lot of these barriers
completely self contained the hydraulic pump could either be located inside or mounted in a control booth there was a nitrogen pressurized accumulator mounted inside .
the system was closed loop not only were there springs inside the cylinders but in-order to retract the barrier the cylinders had to be pumped down then the system was held closed via solenoid valves any disruption in the electrical the barrier deployed and could not be lowered without a 30 ton load or pumped down. If say a car or medium sized truck had its front tires on the barrier plate when it deployed the vehicle would almost be tossed, as the pressure from the accumulator would be expelled into the cylinders at a rate to 200 gallons per minute it took only 2.5 gallons to fully deploy the cylinders or about 1/2 second to go from flat to 3 feet high

These drawings do not show the system
the top plate is 3/4" thick