Cab-over, also known as cab over engine (COE),
cab forward (U.S.), flat nose (Canada), or forward control (UK), is a body style of
truck
A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...
,
bus
A bus (contracted from omnibus, with variants multibus, motorbus, autobus, etc.) is a road vehicle that carries significantly more passengers than an average car or van. It is most commonly used in public transport, but is also in use for cha ...
, or
van that has a vertical front, "flat face" or a
semi-hood, with the
cab of the truck sitting above (or forward of) the front
axle
An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...
. This contrasts with a
conventional truck
A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...
where the engine is mounted in front of the driver.
This truck configuration is currently common among
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
an and
Asia
Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...
n truck manufacturers. European regulations set restrictions for both the total length and the length of the load area, which allow a cab length of in combination with the maximum load area length. This allows a
sleeper cab
A truck sleeper or sleeper cab is a compartment attached behind the cabin of a tractor unit used for rest or sleeping.
Origin
The word "sleeper" references a sleeper car which is a railroad car with sleeping facilities for passengers travelling ...
with a narrow bunk, and would allow a bonneted (hooded) day cab. Nonetheless, no manufacturer in Europe produces such day cabs with bonnets. The last manufacturer of a conventional in Europe,
Scania
Scania, also known by its native name of Skåne (, ), is the southernmost of the historical provinces of Sweden, provinces (''landskap'') of Sweden. Located in the south tip of the geographical region of Götaland, the province is roughly conte ...
, stopped production in 2005. (The reason was a decline to less than 1000 units worldwide, with European sales declining by 50% and sales in South America by 90%, within one decade.) Generally speaking, Asian regulations are even stricter, and the relatively shorter journey distances allow more heavy trucks to forgo sleepers to save even more length.
![Recology Lodal Garbage Truck 14425 in San Francisco](https://upload.wikimedia.org/wikipedia/commons/b/b0/Recology_Lodal_Garbage_Truck_14425_in_San_Francisco.jpg)
Cabover trucks are widely used in the United States for
refuse collection
Waste collection is a part of the process of waste management. It is the transfer of solid waste from the point of use and disposal to the point of treatment or landfill. Waste collection also includes the curbside collection of recyclable m ...
,
terminal tractor
A terminal tractor, known in the United States as a shunt truck, spotter truck, spotting tractor, yard truck, yard shifter, yard dog, yard goat, yard horse, yard jockey, hostler, or mule, is a kind of semi-tractor intended to move semi-trailers ...
s, and other vocational applications requiring a tight turning radius or frequent ingress/egress by the driver.
Autocar, the oldest surviving motor vehicle manufacturer in America, produces primarily cabover trucks. Although cabover trucks were popular among
United States
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
heavy truckers and trucking companies during the 1970s because of strict length laws in many states, when those length laws were repealed, most heavy-truck makers moved to other body styles. One of the reasons is the
Federal Bridge Formula, which is unique to the US, and encourages spreading out the load. If axle distances are too tight, the maximum load allowance is reduced. For COEs operated at maximum weight in the US, this required an axle directly behind the front bumper. This cab design caused an awkward climb into the cab for the driver, forcing them to climb up behind the front wheel, then moving to the front and into the cab. European or Chinese or Japanese truckers enter their cab in a straight fashion with handrails left and right.
Cabovers are also very popular in the US's light- and medium-duty truck segment where compact size is required for urban mobility without sacrificing payload; Toyota subsidiary
Hino,
Isuzu, and
Mitsubishi Fuso models are a regular sight for this reason. American company
Paccar
Paccar Inc is an American ''Fortune'' 500 company and counts among the largest manufacturers of medium- and heavy-duty trucks in the world, and has substantial manufacturing in light and medium vehicles through its various subsidiaries. It was o ...
(which owns the
Kenworth
Kenworth Truck Company is an American truck manufacturer. Founded in 1923 as the successor to Gersix Motor Company, Kenworth specializes in production of heavy-duty ( Class 8) and medium-duty (Class 5–7) commercial vehicles. Headquartered in ...
and
Peterbilt
Peterbilt Motors Company is an List of American truck manufacturers, American truck manufacturer. Established in 1939 from the acquisition of Fageol, Fageol Truck and Motor Company, Peterbilt specializes in the production of heavy-duty (Truck c ...
brands) still manufactures traditional cab over engine designs for the
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
n and
South Africa
South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...
n markets where length restrictions still make them advantageous.
In
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
, both
America
The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...
n (cab over axle) and
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
an/
Japan
Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
ese/
Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of ...
(
cab forward of axle) types, as well as the conventional type are common. Cab over engine types dominate urban and light duty use, with
conventional trucks predominating in remote and off-road areas. Both types are common for highway use.
History
![1958 International Metro Van in Portland in 2012, front](https://upload.wikimedia.org/wikipedia/commons/b/be/1958_International_Metro_Van_in_Portland_in_2012%2C_front.jpg)
The first truck in the United States was built by
Autocar in 1899 using a format then called "engine-under-the-seat" and was available with optional motors.
Although early Autocar trucks were not exactly "cab-over", since the truck did not have a cab, per se, they were the fore-runners to COEs. The Sternberg company of
Wisconsin
Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...
produced cab-over trucks as early as 1907, though by 1914 only their seven-ton model was a cab-over. They reintroduced the cab-over layout in 1933 with their "Camel Back" model, which allowed the cab to be tilted to access the engine.
The introduction of the first modern cab-over layout in the United States is credited to industrial designer
Viktor Schreckengost
Viktor Schreckengost (June 26, 1906 – January 26, 2008) was an American industrial designer as well as a teacher, sculptor, and artist. His wide-ranging work included noted pottery designs, industrial design, bicycle design and seminal re ...
, who, with engineer Ray Spiller, designed a cab-over truck for the
White Motor Company
The White Motor Company was an American automobile, truck, bus and agricultural tractor manufacturer from 1900 until 1980. The company also produced bicycles, roller skates, automatic lathes, and sewing machines. Before World War II, the compa ...
in 1932. Schreckengost was later joined by other designers such as
Raymond Loewy who designed the
Metro
Metro, short for metropolitan, may refer to:
Geography
* Metro (city), a city in Indonesia
* A metropolitan area, the populated region including and surrounding an urban center
Public transport
* Rapid transit, a passenger railway in an urba ...
series of
vans and
truck
A truck or lorry is a motor vehicle designed to transport cargo, carry specialized payloads, or perform other utilitarian work. Trucks vary greatly in size, power, and configuration, but the vast majority feature body-on-frame construction ...
s for
International Harvester
The International Harvester Company (often abbreviated by IHC, IH, or simply International ( colloq.)) was an American manufacturer of agricultural and construction equipment, automobiles, commercial trucks, lawn and garden products, household e ...
. The bodies for these vehicles were initially produced by the
Metropolitan Body Company
Metropolitan may refer to:
* Metropolitan area, a region consisting of a densely populated urban core and its less-populated surrounding territories
* Metropolitan borough, a form of local government district in England
* Metropolitan county, a ...
(MBC). The company produced a wide variety of truck and commercial bodies for several vehicle manufacturers such as Chevrolet, Ford, Dodge Bros., and International Harvester until 1948 when they were purchased by the latter. MBC was instrumental in the development of COE route delivery bodies in the 1930s.
The laws of the time limited overall truck length to on highways. Setting the cab over the engine and front axle shaved several feet off the length of the tractor, feet which could then be added to the length of the trailer while keeping the dimensions of the entire truck within the permissible limit. Schreckengost patented the design in 1934.
Autocar reintroduced the engine-under-the-seat format with their Model U in 1933, which became a staple of U.S. roads and the U.S. military through
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
and well into the 1950s.
White-
Freightliner introduced its first tilting cab-over design in 1958, which allowed the entire cab to tilt forward for access to the engine.
[
]
Design aspects
In Class 8 tractors (using the US designation), the cab-over design allows the vehicle's wheelbase
In both road and rail vehicles, the wheelbase is the horizontal distance between the centers of the front and rear wheels. For road vehicles with more than two axles (e.g. some trucks), the wheelbase is the distance between the steering (front ...
to be shorter than in the conventional arrangement, wherein the engine is placed in front of the cab, covered by a horizontal or sloping hood that opens to allow engine access. Its shorter wheelbase allows cab-over semi truck
A semi-trailer truck, also known as a semitruck, (or semi, eighteen-wheeler, big rig, tractor-trailer or, by synecdoche, a semitrailer) is the combination of a tractor unit and one or more semi-trailers to carry freight. A semi-trailer a ...
s to have a shorter overall length, thereby allowing for longer trailers to be used. For light- and medium-duty solid- or rigid-axle trucks, the cab-over design requires less length for the cab and engine, in a given wheelbase, and therefore allows a greater length for the truck body or load area.
In both class 8 tractors and light- and medium-duty vocational trucks, the cab-over-engine design gives the COE model an advantage in maneuverability over a conventional model. And since COEs are generally lighter than conventionals, they can often haul heavier loads, given equal gross vehicle weight rating (GVWRs) and gross combination weight rating (GCWRs). Despite the COE designs' being smaller in general, over-the-road tractors can still be fully equipped with single or bunk beds. Also, lack of a hood gives better visibility to the driver and a tighter turning radius, and significantly reduces the forward blind spots.
One critique is that the shorter wheelbase in the COE semi-trucks gives a rougher ride than those with conventional cabs, as the driver's seat is above the front axle
An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...
. In the 1970s, COEs used to be noisier, because the engine is directly below. This was an important consideration back then: Interior noise in the cab was between 80 and 90 db(A), creating an unhealthy work environment. , US long distance trucks provide an interior noise level of 60–70 db(A) at highway speed, while European long distance trucks, all built as a COE, provide a level of 60–65 db(A). As highway speeds are a slightly higher in the US, this performance can be viewed as equivalent.
Because of their flat front design, early COE semi-trucks had significantly worse aerodynamics than conventional tractors. Modern cab-over designs, in both semi-trucks and light- and medium-duty models, have improved aerodynamics significantly over early models, but often still have higher drag coefficient
In fluid dynamics, the drag coefficient (commonly denoted as: c_\mathrm, c_x or c_) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water. It is used in the drag equ ...
s than their modern conventional-design counterparts. This works against fuel economy, and offsets some of the improvement in fuel consumption garnered from the lighter weight of the cab-over truck when running less than fully loaded.
Although the tilting cab gives comparatively unobstructed access to the engine, its deployment causes unsecured items in the cab and sleeper (if equipped) to fall onto the windshield or under the instrument panel. Vehicles without a tilting cab will usually be equipped with removable floor panels through which mechanics can access and service the engine. In Europe, Mercedes-Benz was the last manufacturer to use such panels instead of a tilting cab, with the last non-tilting cabs produced well into 1983.
Safety aspects
Truck occupant safety depends on survival space within the cab, with "rollover" being the most significant heavy truck accident causing occupant casualties.
In the 1950s, when many truck cabs were still wooden structures, knowledge about the most common accidents was already established, and led to the first mechanized truck cab crash test in 1959, performed by Volvo. The test became a Swedish standard, and was adopted by the European Community in simplified form as ECE R-29 in 1974. During the early 1980s, the safest place for a truck driver was a European truck, usually a cabover.
Decision-making is based on human perception in first place, results of statistics might not be present. Motor placement before or under the cab does not have much influence on the results of rollovers. Behind the danger of a rollover, heavy truck on heavy truck crashes are the second most relevant reason for occupant casualties. With a 1980s US conventional, the result of such a crash was: Frame, front axle and wheels would go under the truck in front, while the motor got pushed into the cab (which was very small in a 1980s conventional). Contrary to these real-world results, the motor in front, which would crush the truck driver in an crash, was nonetheless perceived as "protection", and this perception was an important factor for the adoption of these trucks in the US, during the 1980s.
Both conventionals and cabovers need structural protection against rollovers, and special protection against massive objects at the height of another truck body. The survival space should be able to move backward on the frame. Today (2017), crash tests have been adopted all over the world (the most important ones still being similar to the Swedish tests of the 1960s), and the 1970s/80s safety advantage of European trucks no longer exists.
In military use, the COE design increases the chance of crew injury or death in the event of running over a landmine
A land mine is an explosive device concealed under or on the ground and designed to destroy or disable enemy targets, ranging from combatants to vehicles and tanks, as they pass over or near it. Such a device is typically detonated automati ...
. This is because the tire that detonates the mine is directly below/beside the driver.
See also
*Kei truck
A kei truck, kei-class truck, or Japanese mini truck is a mini truck, a tiny but practical pickup truck available in rear-wheel drive or four-wheel drive versions, built to satisfy the Japanese '' keijidōsha'' (軽自動車, "light vehicle") st ...
References
{{Automobile configuration
Automotive styling features
Buses
Vans
Trucks
Vehicle design
Cab over vehicles