Cab over

Volvo FH cab-over
Overview
Manufacturer	Various
Also called	COE, forward control
Production	1899–present
Assembly	Worldwide
Body and chassis
Class	Light, medium, and heavy
Body style	Cab over engine

Cab-over, also known as cab over engine (COE),

where the engine is mounted in front of the driver.

This truck configuration is currently common among

, stopped production in 2005 due to a decline in sales 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.

Cabover trucks are widely used in the United States for

, 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;

markets where length restrictions still make them advantageous.

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

Metro Van

in Portland, Oregon in 2012

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 5 or 8 horsepower (3.7 or 6.0 kilowatts) motors.^[1] 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 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.^[2]

The introduction of the first modern cab-over layout in the United States is credited to industrial designer

The laws of the time limited overall truck length to 42 feet (12.8 m) 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 and well into the 1950s.[1]

White-Freightliner introduced its first tilting cab-over design in 1958, which allowed the entire cab to tilt forward for access to the engine.^[2]

Design aspects

In

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

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

dB(A)

.

Because of their flat front design, early COE semi-trucks had significantly worse

than their modern conventional-design counterparts.

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

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 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.

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).^[7][8]

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.

In military use, the COE design increases the chance of crew injury or death in the event of running over a

See also

• Terminal tractor
• Tractor unit
• Kei truck
• List of Low Cab Forward trucks

References