Description
Swap bodies, often also referred to as swap trailers, swap containers, or swap bodies (other names include swap flatbeds or swap boxes, abbreviated as WAB), are interchangeable cargo carriers used similarly to sea containers in combined (intermodal) transport. They are equipped with gripping edges for crane handling at terminals, container corners for locking with twistlocks on trucks and freight wagons, and support legs for parking and swapping without lifting equipment.
The locking dimensions of swap trailers are identical to those of a 20-foot sea container, allowing the same vehicle to transport both types without modification in most cases. The significant advantage of swap bodies lies in their dimensions, which enable optimal utilization with Euro pallets. See also our list "Pallets in a Container."
History The development of swap bodies began in the early 1950s in America with the development of sea containers. Around the same time, the German Post began developing specialized parcel containers for road and rail transport. Both developments aimed at accelerating cargo handling and reducing the downtime of the vehicles used.
The modern swap trailer with support legs, as known today, was developed from 1971 by the Dachser forwarding agency. Previously used swap containers had to be changed laboriously with cranes or forklifts. The foldable support legs made it possible from this point to set down and pick up the complete swap body from the truck without additional tools.
Dimensions The lengths for swap trailers are fixed:
7,150 mm (C 715) 7,450 mm (C 745) 7,650 mm (C 765) 7,820 mm (C 782) 13,600 mm (rare, locking measure for 40-foot sea containers) The usual external height of about 2,670 mm is exceeded in volume versions with an external height of up to 3,200 mm. The usual width is 2,550 mm, and for refrigerated boxes, it's 2,600 mm. The base group of the swap containers is designed with a centering tunnel that has a pass-through width of 600 mm, a web width of 60 mm, and a tunnel height of 90 mm. The bottom edge of the tunnel and the bottom edge of the corner fittings are on the same level.
A swap container has four standardized support legs with diagonal braces and a double transport security (spring bolt at the support tube, drop bolt at the frame). The position of the supports is set at 4,354 mm (A1) for the C 715 model and at 5,523 mm for the longer swap boxes (from C 745).
The parking heights vary from 980 mm (volume versions, jumbo swap boxes) to 1,320 mm (standard). Some swap boxes have telescopic support legs, allowing the parking height to be adjusted to the vehicle type.
Features & Benefits
Since swap trailers, unlike sea containers, are a European development, their dimensions are adapted to the sizes of EURO pallets. The common swap boxes produced as C-containers according to EN 284 offer 17 pallet spaces for Euro pallets in the 7.15 m long version and 18 spaces at 7.45 m length. The slightly rarer 7.820 m long swap containers have 19 Euro pallet spaces. There are now also steel swap boxes and refrigerated swap trailers with a so-called double-deck loading facility to better utilize the available space and load goods in two layers. This optimal utilization is probably the most significant advantage of swap trailers over sea containers in intracontinental transport.
A second advantage becomes evident in warehouse use. Pipes and assembly rails made of metal or plastic are usually 6 meters or slightly longer and cannot be accommodated in a 20-foot sea container with an interior length of 5.9 meters. Here, the swap boxes with an internal length of about 7 meters are clearly superior.
Usage
Swap boxes were originally designed as flexible and mobile transport solutions for daily forwarding operations. With the support legs folded in and the swap container set up at ground level, it can be comfortably entered and used as storage. The common design with an aluminum roller door even allows the permanent attachment of a ramp or an underground installation with almost ground-level access without a step. This makes driving with pallet trucks or forklifts easy.
When set up with unfolded support legs at ramp facilities, the swap boxes serve as additional, also forklift-accessible, expansion storage.