Almost all trucks share a common construction: they are made of a
chassis, a
cab, an area for placing
cargo or equipment,
axles,
suspension and
roadwheels, an
engine and a
drivetrain.
Pneumatic,
hydraulic,
water, and
electrical systems may also be present. Many also tow one or more
trailers or semi-trailers.
Cab The "cab", or "cabin" is an enclosed space where the driver is seated. A "
sleeper" is a compartment attached to or integral with the cab where the driver can rest while not driving, sometimes seen in semi-trailer trucks. There are several cab configurations: • "
Cab over engine" (COE) or "flat nose"; where the driver is seated above the front axle and the
engine. This design is almost ubiquitous in Europe, where overall truck lengths are strictly regulated, and is widely used in the rest of the world. They were common in North American heavy-duty trucks but lost prominence when permitted length was extended in the early 1980s. Nevertheless, this design is still popular in North America among medium- and light-duty trucks. To reach the engine, the whole cab tilts forward, earning this design the name of "tilt-cab". This type of cab is especially suited to the delivery conditions in Europe where many roads require the short turning radius afforded by the shorter wheelbase of the cab over engine layout. • "Cab-under" is where the driver is positioned at the front at the lowest point possible as means for maximum cargo space as possible. Examples were made by Hunslet, Leyland, Bussing, Strick and Steinwinter. • "Conventional" cabs seated the driver behind the engine, as in most passenger cars or pickup trucks. Many new cabs are very
streamlined, with a sloped hood (bonnet) and other features to lower drag. Conventional cabs are the most common in North America, Australia, and China, and are known in the UK as "American cabs" and in the Netherlands as "torpedo cabs". • "Cab beside engine" designs are used for
terminal tractors at
shipping yards and for other specialist vehicles carrying long loads such as pipes. This type is often made by replacing the passenger side of a cab-over truck with an extended section of the load bed. A further step from this is the side loading
forklift that can be described as a specially fabricated vehicle with the same properties as a truck of this type, in addition to the ability to pick up its own load.
Engines and motors 6.7L medium-duty truck diesel engine Most small trucks such as
sport utility vehicles (SUVs),
vans or
pickups, and even light medium-duty trucks in North America, China, and Russia use
gasoline engines (petrol engines), but many
diesel engined models are now being produced. Most of the heavier trucks use
four-stroke diesel engines with a
turbocharger and
intercooler. Huge off-highway trucks use locomotive-type engines such as a
V12 Detroit Diesel two stroke engine. A large proportion of refuse trucks in the United States employ
CNG (compressed natural gas) engines for their low fuel cost and reduced carbon emissions. A significant proportion of North American manufactured trucks use an engine built by the last remaining major independent engine manufacturer (
Cummins) but most global OEMs such as
Volvo Trucks and
Daimler AG promote their own "captive" engines. In the European Union, all new truck engines must comply with
Euro VI emission regulations, and Euro 7 from the late 2020s has stricter exhaust limits and also limits
air pollution from brakes and tires. several alternative technologies are competing to displace the use of diesel engines in heavy trucks. CNG engines are widely used in the US refuse industry and in concrete mixers, among other short-range vocations, but range limitations have prevented their broader uptake in freight hauling applications. Heavy
electric trucks and
hydrogen-powered trucks are new to the market in 2021, but major freight haulers are interested. Although cars will be first the
phase-out of fossil fuel vehicles includes trucks. According to
The Economist magazine "Electric lorries will probably run on hydrogen, not batteries, which are too expensive." Other researchers say that once faster
chargers are available batteries will become competitive against diesel for all, except perhaps the heaviest, trucks.
Drivetrain Small trucks use the same type of
transmissions as almost all cars, having either an automatic transmission or a manual transmission with
synchromesh (synchronizers). Bigger trucks often use manual transmissions without synchronizers, saving bulk and weight, although synchromesh transmissions are used in larger trucks as well. Transmissions without synchronizers, known as "crash boxes", require
double-clutching for each shift, (which can lead to repetitive motion injuries), or a technique known colloquially as "floating", a method of changing gears which does not use the clutch, except for starts and stops, due to the physical effort of double-clutching, especially with non-power-assisted clutches, faster shifts, and less clutch wear. Double-clutching allows the driver to control the engine and transmission revolutions to synchronize so that a smooth shift can be made; for example, when upshifting, the accelerator pedal is released and the clutch pedal is depressed while the gear lever is moved into neutral, the clutch pedal is then released and quickly pushed down again while the gear lever is moved to the next higher gear. Finally, the clutch pedal is released and the accelerator pedal pushed down to obtain the required engine speed. Although this is a relatively fast movement, perhaps a second or so while the transmission is in neutral, it allows the engine speed to drop and synchronize engine and transmission revolutions relative to the road speed. Downshifting is performed in a similar fashion, except the engine speed is now required to increase (while the transmission is in neutral) just the right amount in order to achieve the synchronization for a smooth, non-collision gear change. "Skip changing" is also widely used; in principle, the operation is the same as double-clutching, but it requires neutral be held slightly longer than a single-gear change. Common North American setups include 9, 10, 13, 15, and 18 speeds.
Automatic and
automated manual transmissions for heavy trucks are becoming more and more common, due to advances both in transmission and engine power. In Europe, 8, 10, 12, and 16 gears are common on larger trucks with a manual transmission, while conventional automatic or automated manual transmissions would have anything from 5 to 12 gears. Almost all heavy truck transmissions are of the "range and split" (double H shift pattern) type, where range change and so‑called half gears or splits are air operated and always preselected before the main gear selection.
Frame A truck
frame consists of two parallel boxed (tubular) or C‑shaped rails, or beams, held together by
crossmembers. These frames are referred to as
ladder frames due to their resemblance to a ladder if tipped on end. The rails consist of a tall vertical section (two if boxed) and two shorter horizontal flanges. The height of the vertical section provides opposition to vertical flex when weight is applied to the top of the frame (beam resistance). Though typically flat the whole length on heavy-duty trucks, the rails may sometimes be tapered or arched for clearance around the engine or over the axles. The holes in rails are used either for mounting vehicle components and running wires and hoses or measuring and adjusting the orientation of the rails at the factory or repair shop. The frame is usually made of
steel, but can be made (whole or in part) of
aluminum for a lighter weight. A
tow bar may be found attached at one or both ends, but heavy tractors almost always make use of a
fifth wheel hitch.
Body types Box trucks have walls and a roof, making an enclosed load space. The rear has doors for unloading; a side door is sometimes fitted.
Chassis cab trucks have a fully enclosed cab at the front, with bare
chassis frame-rails behind, suitable for subsequent permanent attachment of a specialized payload, like a
fire-truck or
ambulance body.
Concrete mixers have a rotating drum on an inclined axis, rotating in one direction to mix, and in the other to discharge the concrete down chutes. Because of the weight and power requirements of the drum body and rough construction sites, mixers have to be very heavy duty.
Dual drive/Steer trucks are vehicles used to steer the rear of
trailers.
Dump trucks ("tippers" in the UK) transport loose material such as sand, gravel, or dirt for construction. A typical dump truck has an open-box bed, which is hinged at the rear and lifts at the front, allowing the material in the bed to be unloaded ("dumped") on the ground behind the truck.
Flatbed trucks have an entirely flat, level platform body. This allows for quick and easy loading but has no protection for the load. Hanging or removable sides are sometimes fitted, often in the form of a
stakebody.
Refrigerator trucks have insulated panels as walls and a roof and floor, used for transporting fresh and frozen cargo such as ice cream, food, vegetables, and prescription drugs. They are mostly equipped with double-wing rear doors, but a side door is sometimes fitted.
Refuse trucks have a specialized body for collecting and, often, compacting trash collected from municipal, commercial, and industrial sites. This application has the widest use of the
cab-over configuration in North America, to provide better maneuverability in tight situations. They are also among the most severe-duty and highest
GVWR trucks on public roads.
Semi-tractors ("artics" in the UK) have a fifth wheel for towing a semi-trailer instead of a body.
Tank trucks ("tankers" in the UK) are designed to carry
liquids or
gases. They usually have a cylindrical tank lying horizontally on the chassis. Many variants exist due to the wide variety of liquids and gases that can be transported.
Wreckers ("recovery lorries" in the UK) are used to recover and/or tow disabled vehicles. They are normally equipped with a boom with a cable; wheel/chassis lifts are becoming common on newer trucks. ==Sales and sales issues==