Flatbed truck
A flatbed truck is a type of truck which can be either articulated or rigid. Its name is taken from a famous event that took place on the coast of Northern New South Wales in Australia, in 1898. The story goes that a keen angler pulled in a 10 metre flathead, and carted it home on a modified truck he had recently completed. After driving the flatty home he fed the whole town.
Road trucks
A flatbed has a solid bed, usually of wooden planks. There is no roof and no fixed sides. To retain the load there are often low sides which may be hinged down for loading, as a 'drop-side' truck. A 'stake truck' has no sides but has steel upright pillars, which may be removable, again used to retain the load.Loads are retained by being manually tied down with ropes. The bed of a flatbed truck has tie-down hooks around its edge and techniques such as a trucker's hitch are used to tighten them. Weather protection is optionally provided by manually 'sheeting' the load with a tarpaulin, held down by ropes. These manual loading techniques are slow and require some care and skill. There is also the risk that an improperly secured load may be shed in transit, often leading to accidents or road blockages. There is also little theft protection for such a load. The slowness of loading loads like this led to the development of more efficient truck designs with enclosed bodies.
Some improvement was made with the general replacement of ropes by flat webbing straps, tightened with a ratchet. These reduced the skill of 'roping up' and improved the control of tension, leading to fewer shed loads.
Decline of flatbeds
Flatbeds became rare in the 1980s as the majority of road freight changed to either containers or pallet loads carried on larger and more efficient trucks, optimised for quicker loading by fork-lift trucks. Containers are carried on specialised semi-trailers with twistlocks in the corners to retain the container. Pallet loads are carried in either box bodies, loaded through rear doors, or curtain-sided bodies loaded through the sides. Both of these protect loads from the weather and can be quickly loaded with standard loads, but are more restrictive for single bulky loads, loaded by crane. The haulage and logistics business also changed around the same time as a greater proportion became more regular in nature, such as standard daily loads of equally-sized boxes from a distribution centre to a supermarket, rather than the unpredictable ad hoc nature or earlier road transport.Flatbeds are still in use, but are now used for more specialised cargoes, such as constructional steelwork or lighter abnormal loads, such as machinery, lumber loads/dry wall or any load that requires use of a forklift without the use of a loading dock.
Low loaders, for construction machinery and heavy plant vehicles, are not considered as flatbeds. Neither are abnormal load carriers for heavy haulage.
Configuration/design in US trailers
In North America, the length is commonly 48 feet or 53 feet, and the width is either 96 or 102 inches. Some older trailers still in service are only 45 feet or shorter if used in sets of doubles or triples. Various lengths and combination setups can only be legally driven on turnpike/toll roads which are far too long for most roadways. Body and frame can be one of 3 general designs: the heaviest and sturdiest is all steel, and aluminium. Incredibly light and very expensive to purchase, all aluminium trailers are very slippery when wet, flex more and are easily damaged. They also have a natural upwards bend so that when loaded they straighten out to be flatter, rather than to sag in the middle under a load.Another popular type of flatbed trailer is a step deck with approximately 2 feet lower deck and low profile wheels to accommodate taller loads, without hitting low bridges or tunnels. These stepdecks can come with loading ramps to allow vehicles to roll on and off of the back from ground level. Shorter trailers used for local jobs such as landscaping and building material delivery within urban or local areas can have a "hitchhiker" type forklift truck attached to the back in order for driver alone to deliver and unload pallet/skid items. A bulkhead or "headache rack" is sometimes be attached to the front of either a straight or a stepdeck trailer for load securement at the front of the deck. In the event of long pipes or steel or lumber coming loose in a hard braking incident, they save the operator and cab/sleeper in one of two manners in theory. If attached to the trailer they bend while attempting to block forward motion of a loosened cargo, causing the long load to go above the cab and driver.
If attached to the frame behind the cab or sleeper of the tractor, in theory, they protect the back of the cab from impact and if unable to stop the load coming through the cab, they cause the cab to be knocked off of the frame, rather than impale the cab and kill or seriously injure the driver. 48- and 53-foot lengths usually have two axles spread out to over 10 feet apart at the rear "California spread" in order to allow for more weight distribution on the rear of the deck. The so-called Cali spread was originally designed to comply with bridge weight formulas in that state but has since been adopted in most other parts of the country. These spread axles take a far wider turning radius, and if turning the combination tractor/trailer too sharply, the front axle tires of the trailer may damage the road/parking lot surface, or pop a tire bead off of the rim, or both. Some trailers have the capability of lifting or lowering the front axle independently to mitigate this risk. The driver may not be able to use this feature if the trailer is loaded, but if the deck is empty the driver can lower the front axle to bring the rear axle off of the ground to significantly decrease the turning radius of the rig for easy maneuvering in tight spaces, or to reduce tire wear during empty/deadhead miles of travel.
Under the deck of the trailer can be attached racks for spare tires, dunnage boards, or tire chains, as well as various tool/storage boxes. On one side are usually sliding winches to ratchet down 4 inch straps for load securement. On most 48 foot trailers, you may not place these strap/winches over a tire as when air pressure releases out of the suspension system when parked, the deck lowers down and will likely pop a trailer tire. Some trailers have an air scale. When the driver learns how to interpret the scale properly through experience, combined with his knowledge of how much his/her rig weighs when empty, he can interpret how much cargo can safely and legally be loaded onto the trailer. With different varying loads of cargo, the driver can have an idea how much his gross total weight is . Some decks have pop-up chain systems which have a higher WLL than attaching chains to either the stake pocket/spools, or the frame.
Other decks of trailers can have sliding detachable accessories which greatly diversify the options of where and how to place a chain hook for securement. Besides axles which raise/lower as needed, some spread axle trailers can slide one or both axles forward, or back to create a tandem setup in specific situations when necessary, to comply with weight distribution requirements. Certain amounts of front and rear cargo overhang are allowed with flags/banners/flashing lights to warn drivers behind and to the side of impending danger of impalement if they follow too closely behind and the truck suddenly stops. In extreme cases, permit loads require an escort vehicle in the front, rear, or both for oversize/over dimension cargo/equipment.