Auto-Rack Railcar

Overview

The Auto-Rack Railcar is an enclosed freight car built to carry finished automobiles from assembly plants to distribution ramps. Rather than haul vehicles on an open deck, it stacks them on two or three levels inside a steel cage so a single car moves ten to fifteen automobiles at once. The base of the car is a conventional Flatcar Underframe underframe, on top of which a bolted Rack Superstructure superstructure carries the upper decks. A Side Security Screen encloses both sides against vandalism and debris, End Door Assembly open the ends so vehicles can drive through from car to car, and a Tie-Down System system locks each vehicle to its deck. The car rolls on two Freight Bogie freight bogies, connects through a Cushioned Coupler cushioned coupler, stops under an Air Brake System system, and carries the Safety Appliances ladders and handholds required of every interchange car. A tri-level car runs about 60 tonnes empty and stands roughly 6.15 metres tall, near the limit of the loading gauge.

Flatcar base and rack structure

The lower structure is the Flatcar Underframe, a welded flatcar whose Center Sill box beam runs the full length as the main draft and buff member. Two Side Sill members run along the edges, twelve Cross Member beams span between them, and an End Sill closes each end with the coupler pocket. At each bogie position an Body Bolster transfers the car weight to the bogie center plate, and an Lower Deck Plate forms the lowest vehicle deck. Above this base, the Rack Superstructure is a bolted steel frame: four Corner Post columns anchor the corners, twelve Intermediate Post columns stiffen the sides, and Roof Cross Tie members square the frame under a fixed Roof Panel. Each Upper Deck Level is built from Deck Stringer channels carrying Adjustable Deck Panel sections that ride on pinned Deck Hanger hangers, with Deck Grating tread giving traction. Because the panels move on the hangers, an operator can raise or lower a deck to fit tall pickups on one car and low sedans on the next.

Side screens and weather protection

Open auto racks of the 1960s lost large numbers of vehicles to thrown rocks and pilferage, so modern cars are fully enclosed. The Side Security Screen wraps both sides in Perforated Screen Panel perforated panels held in Screen Frame frames bolted to the columns, with solid Sheet Metal Panel skirts at the bottom and Ventilation Louver louvers near the roof. The perforations block stones and casual entry while still passing air, which matters because a sealed steel box in summer sun would otherwise bake the paint and interior trim of the cars inside. The fixed roof and the screens together turn the rack into a weatherproof shell that keeps the finished vehicles clean and undamaged across a journey of several days.

Loading and tie-down

Auto racks load by driving vehicles up a fixed ramp at one end of a coupled string and through every car in turn. The End Door Assembly swing open on heavy Door Hinge hinges, and a Bridge Plate folds down to span the gap between cars so a vehicle drives across the coupler line without a step. Each End Door Leaf is locked shut for transit by a Door Latch. Once a vehicle is spotted on its deck, the crew secures it with the Tie-Down System set: Wheel Chock chocks slide into an Chock Track track and lock fore and aft of each tire, while a Restraint Strap strap over the tire is drawn tight by a Strap Ratchet ratchet. Securing the tires rather than the body lets the suspension absorb shock and avoids stress on the vehicle structure.

Running gear and cushioned couplers

The car rides on two Freight Bogie three-piece freight bogies, each with two cast Bogie Side Frame side frames, a Bogie Bolster bolster carried on a Coil Spring spring nest, and a pair of Wheelset wheelsets. Every wheelset is a forged Axle pressed with two monobloc Rail Wheel wheels turning on Ball Bearing journal bearings, and Friction Wedge wedges damp the suspension. What sets the auto rack apart from ordinary freight cars is the Cushioned Coupler: an AAR Coupler Head head with a pivoting Knuckle mounted on a long-travel Cushioning Unit cushioning unit through a Draft Yoke yoke, backed by an elastomer Draft Gear. The cushioning gives about 380 millimetres of travel in each direction so the slack action of a long train, which would slam a rigid car, is absorbed before it reaches the vehicles. Braking is handled by the Air Brake System: an Brake Control Valve meters air from the Air Reservoir into Brake Cylinder cylinders that drive the Brake Rigging against the Brake Shoe shoes, with a Hand Brake for parking and a Pressure Sensor on the Brake Pipe.

Variants and use

Auto racks come in two main forms. The bi-level car carries two decks and is used for tall vehicles such as pickup trucks, vans, and sport utility vehicles, holding around eight to ten units. The tri-level car carries three decks for low passenger cars and holds ten to fifteen. Because the Adjustable Deck Panel panels adjust on their hangers, many cars can be reconfigured between the two patterns at a service track to match the mix of vehicles a plant is shipping. The enclosed rack rides on a standard flatcar in unit trains routed from assembly plants to distribution ramps, where the Safety Appliances End Ladder ladders, Handhold handholds, and Running Board running boards let crews open the doors and unload. Held with a Fastener Set at its bolted joints and protected by its screens and cushioned draft gear, the auto rack delivers new vehicles with the low damage rate the automotive trade requires.