Armored Truck

How Products are Made, Volume 4 (1996) by Michael Cavette

Gross Vehicle Weight (GVW) measures the maximum a motor vehicle can safely weigh, including its cargo and passengers. The average GVW for a "route truck," which makes everyday pickups and deliveries for banks and merchants, is 25,000 lb (11,350 kg). The average finished route truck weighs 12,000 lb (5,448 kg). This leaves 13,000 lb (5,902 kg) for cargo and guards. Reducing the finished weight of a truck allows for greater cargo weight. Decreasing the amount of armoring is not an attractive option, so trucks that need to haul heavier cargo, such as coins, must be built on larger, heavier chassises. A tandem-axle truck designed to haul large pallets of coin can have a GVW upwards of 55,000 lb (24,970 kg).

The third design consideration is security. Clearly, bullet resistance is of little use if the truck's operators and cargo are not securely separated from the outside world. With this in mind, security measures are aimed at installing and maintaining barriers. Most armored cars operate with two armed guards—a driver, who never leaves the vehicle, and a second guard known as a hopper, who rides in the cargo hold and carries valuables to and from the truck. The driver's compartment is separated from the cargo area by a steel bulkhead. The doors through which the hopper travels are fitted with slam locks, which automatically lock when the door swings shut. Once these doors are locked, the driver must reopen them electronically from the inside. Inside the cargo area, the hopper may place valuables inside a locked box, or he may use a drop safe, which has a one way chute and can only be opened once the truck has returned to its home facility. The gun ports installed in each door employ a spring-loaded plate that must be slid open from the inside to prevent assailants from using them to fire into the vehicle. The security requirements necessitate additional steps to accomplish the final design goal—crew comfort.

An armored car is basically a large, sealed metal box and is thereby very hot inside. The windows do not roll down for obvious reasons, so most trucks have four roof vents with a baffle to obstruct any direct lines of fire into the truck. Trucks are also fitted with dual air-conditioning and heating units, so the hopper and driver can independently adjust temperatures. The walls, ceiling, and floor of the cargo area are lined with light-weight foam-board insulation to further regulate inside temperatures.

The Manufacturing Process

Chassis

1 The production of an armored car begins with the delivery of a bare heavy duty truck chassis. The chassis arrives with complete drive train (engine and transmission) and suspension systems. Some manufacturers take delivery of a chassis with a full cab, which they cut off. Then they reuse many of the interior pieces. Others use a cowl chassis, which only arrives with fenders and a hood.

Body

2 The body of an armored truck is built much in the same way a house is framed. First, sections of square steel tubing are laid out vertically on a table known as a jig that represents the shape of an individual wall. Then lengths of steel channel called hat rails (because the cross section resembles a flat-brimmed hat) are laid horizontally at specific intervals across the vertical sections of tubing and tack-welded to hold them in place. Shortened sections of tubing and hat rail are used in certain areas to leave spaces that will become windows and doors. The process is repeated on the appropriate jig for each wall and for the roof, floor, and bulkhead. 3 Meanwhile, large sheets of hardened steel are being formed into outside body panels. The sheets are first cut to the correct size by enormous hydraulic shears. The cut panels are then rolled onto a table where the openings for windows and doors are cut with high temperature plasma torches. Some manufacturers employ welders to operate the torches, while some use computer-controlled robotic arms to handle the cutting. With this robotic system, plans are drawn on a computer; the computer then instructs the robotic arms to cut the exact shapes and dimensions to match the plans. The robotic arms slide vertically along an overhead track to accomplish vertical cuts, while rollers in the cutting table slide the steel across the path of the torch to handle horizontal cuts. The panels are then rolled onto various hydraulic presses where the necessary curves and angles are formed. Once the steel has been cut and formed into its appropriate shape, it is fitted against its corresponding frame and welded or riveted in place. 4 The floor is the first structure to be lifted onto the waiting chassis. First a sheet of hardwood is placed on the chassis' frame rails to insulate against vibration. Then the floor is placed on the hardwood and is attached to the chassis at several points with a number of c-shaped clamps. The walls are then each lifted onto the chassis and are tack welded or temporarily clamped where they join the floor and where their corners meet. Then the roof is placed on top of the walls. Once the entire structure has been checked for straightness and fit, all the joints and seams are thoroughly welded or riveted.