HARRY DICKINSON knows the sound of an 18-wheel trailer truck being stopped cold at 50 miles per hour or the zing of machine-gun bullets glancing off armor-plated steel.
That's why the former aerospace design engineer stands behind the products he sells but would just as soon move well to the side when they are being tested.
Mr. Dickinson is a man terrorists love to hate. He is to modern security what ''Q'' was to James Bond: A guy who comes up with gizmos to repel bad guys.
Here at Delta Scientific Corporation, America's largest seller of counterterrorism equipment, the bespectacled, affable Dickinson is bracing for a new rush of orders from his ''crash-rated, vehicle-arrest systems'' catalog.
With an entire nation fixated on what more can be done to stop terrorism in the aftermath of the Oklahoma City bombing, demand for his pop-up curbs, bullet-proof guard booths, and other products is expected to pick up as federal and local authorities look for new ways to protect public and private buildings.
''People are more and more concerned about those in society with a destructive bent,'' says Dickinson, a former vice president at TRW Aerospace. ''The growth of this company is living proof of their desire to do something about it.''
Twenty years ago, Dickinson left TRW and began tinkering with designs for parking lot gates in his Glendale, Calif., garage. He patented the tire-shredding exit-spikes (''saber-toothed traffic controllers'') so commonplace -- and irksome -- at parking lots across the country.
He now presides over Delta Scientific, which manufactures about 90 percent of the hydraulic- and structural-steel barricades sold in the US. His devices protect key airport terminals and nuclear plants. Clients from the US State Department to the Mideast and South Africa now bring his company $12 million annually, choosing equipment from his syllable-rich product line:
Series TT212E Enhanced Cable Reinforced Crash Barrier with Hydraulic Actuation, for instance. Or a Series TT224 Single Lane Phalanx Barricade. All are variations of gates, curbs, or steel cylinders that snap into place at the touch of a button to repel or block unwanted vehicles or intruders.
At the Delta Scientific plant here, 100 employees are spread out over 70,000 square feet of warehouse that looks more like a workaday metal shop than a high-tech redoubt for 007. Sparks fly from welders. Saws whir. Drills hum.
Eleven of Dickinson's designs for hydraulic posts, curbs, structural-steel gates, and bullet-proof guard booths carry US patents. Upstairs, in the hallway outside his office, photographs show the steady growth of demand that began after the bombing of the US Embassy in Beirut in 1983. His equipment has been installed at nearly every US embassy around the world, on Capitol Hill, the World Trade Center, and Buckingham Palace.
As terrorists have gotten more sophisticated, so have products to stop them. Special digital detectors now warn guards of the weight and speed of approaching cars and trucks, so security forces know more about a vehicle entering a site.
Security fences, lights, alarms, and gates are integrated into single systems that narrow the ''window of vulnerability.'' Barriers -- say, a fake curb -- pop up and retract more quickly, and many of them can be operated from remote locations.
The barriers are so fast, in fact, that a limousine carrying Secretary of Defense William Perry was damaged to the tune of $7,500 when it tailgated another car going into the Pentagon -- and unexpectedly triggered the device.
''We went with Delta because no two entries [to the Pentagon] are the same and we wanted automatic controls in complex configurations,'' says Tolly Prather, a security specialist at the Pentagon. ''For closing off entries, exits, and passageways, they really do the job.''
Still, Dickinson is the first to admit that there are limits to what technology can do to stem attacks. The first thing he says clients must do is expand the no-access zones around the buildings they want to protect.
''What we manufacture here couldn't have stopped the kind of attack on the federal building there,'' says Dickinson, pointing to a photo of the hydraulic, so-called ''bollards'' that he designed for 22 entrances and exits at the US Capitol in Washington.
The devices, which look like midget telephone poles, rise from the ground at the push of a button and can tear the axle off a speeding car. Larger gates can stop a 15,000-pound truck speeding at 50 m.p.h. in its tracks. Price tag for three bollards and a six-foot curb with remote control (uninstalled): about $50,000.
''These products are designed to prevent penetration of a secure perimeter -- but won't handle a car that is parked adjacent to a building [like in Oklahoma City],'' he says. The Pentagon is expanding such perimeters around the Pentagon.
''For a short time, the emphasis of demand shifted from from physical protection to electronic protection,'' he says. Increases in bombings across the Middle East to New York City returned the focus of interest to preventive barricades, he says.