What Does Off Highway Use Mean?
Off highway use is quite simply the use of a vehicle in an off-road environment. While many OHVs can also be driven on the road, with the correct license plates, others are primarily used away from public lands and roads, specifically for OHV recreation.
For the purposes of this FAQ we will differentiate between construction and agricultural OHVs and ATVs.
What is the Difference between OHV and ATV?
An OHV generally means a 4X4 type off highway vehicle that is built using automotive manufacturing techniques. An ATV is generally a smaller type of off-road vehicle, including those built by motorcycle manufacturers.
While many OHVs are used in construction and agriculture (also known as ‘heavy machines’), there are also several types of OHV that are not used for industrial applications, including:
All Terrain Vehicles (ATV)
ATVs include three or four-wheeled bikes that use low pressure tyres. These vehicles are not street legal in some areas, such as certain states and provinces in Australia, Canada and the United States. OHV use permits and OHV registration are often used to ensure the safe and responsible operation of these types of vehicle and they also need to meet emissions standards, although these can differ from those for road-based vehicles. They generally use a handlebar for steering, with the driver straddling the vehicle on a seat as with a motorcycle.
Recreational Off-Highway Vehicles (ROV)
Other types of OHV include those used for recreation. These have four or more wheels and bench or bucket seats as well as automotive controls for steering throttle and brakes (as opposed to a motorcycle type control and steering system). These vehicles will also often incorporate roll bars, occupant restraints and can reach speeds of over 30mph. They are often raced in motor sports.
Utility Task Vehicles (UTV)
Other OHVs that are not used in industry or agriculture include utility vehicles that have many of the same capabilities of ROVs. These vehicles are similar to ROVs in many aspects and can be used for purposes such as sight-seeing in areas where there is low traction or difficult ground to cover. The high clearance and traction offered by these vehicles make them ideal for this role, although many UTVs have maximum speeds of 30mph or less.
The history of the development of heavy machines for industrial use and other types of OHV happened in parallel, but until the 19th century and into the early 20th century the work done by today’s heavy agricultural machines was done by animal or human power. The advent of steam engines saw this change as early types of combine harvester and steam tractor appeared. The next change for these machines came with the internal combustion engine with kerosene and ethanol engines giving way to diesel. 1917 saw the first mass-produced heavy machine, the Fordson tractor.
Construction vehicles, meanwhile, had their roots in the first continuous tracked vehicle, the 1901 Lombard Steam Log Hauler. Of course, tracks were also used on tanks during World War I before going on to be used on civilian machinery, such as the bulldozer. Bucket wheel excavators, the largest mobile land machines have been built since the 1920s, while there was also a growth in smaller electric powered vehicles, such as the forklift.
As mentioned, this industrial vehicle development happened in parallel with the growth of other OHVs. Between 1906 and 1916, Adolphe Kégresse designed the original Kégresse track, a conversion for the car of Czar Nicholas II of Russia that used a caterpillar track that has a flexible belt rather than interlocking metal segments. This system could be fitted to a conventional truck or car so that it became a half-track able to traverse rough or soft ground. Kégresse returned to his native France following the 1917 Russian Revolution and used the system on Citroën cars between 1921 and 1937. These off-road and military vehicles were the forerunners of many of today’s OHVs.
Thomas Poulter designed the first large wheeled vehicle between 1937and 1939 with the creation of the Antarctic Snow Cruiser. Despite the many innovative features, this vehicle was eventually abandoned as it failed to perform under difficult conditions as required.
The growth of the smaller utility vehicle market followed World War II, with the Jeep being a particularly notable example. This led to a growth in recreational off-road use among civilians and the creation of similar vehicles by Land Rover in the UK and Toyota, Datsun/Nissan, Suzuki, and Mitsubishi in Japan. These early examples were developed from the 1960s onwards, with more luxuries being added to them over the ensuing decades and leading to the development of the crossover and Sports Utility Vehicles (SUV) of today.
As with regular electric vehicles, many heavy machine manufacturers are now working on fully or partially electric-powered equipment. Commercially-available models have begun to reach the market, with more in development. Manufacturers of heavy machine OHVs are also investigating robotics and autonomy, with a few examples now reaching the market.
As the drive towards more environmentally-friendly solutions and the push towards Net Zero continues, we can expect these developments to continue increasing in number over the next few years.
Characteristics of Off Highway Vehicles
While OHV can differ widely in design they do tend to share some common characteristics.
They all need low ground pressure so as not to sink into soft ground, they need good ground clearance so they do not get caught on obstacles and they need their wheels or tracks to stay in contact with the ground so as to maintain traction. Wheeled vehicles maintain traction by using large or additional tyres along with high and flexible suspension. Track vehicles maintain ground contact by using wide tracks and flexible suspension on any wheels (as in half-tracks).
Most off highway vehicles also use low gearing, which means the much of the engine’s power is still available even while moving slowly across difficult terrain. This is usually due to a very low first gear (called a ‘granny’) or an extra gearbox in line with the first (called a ‘reduction drive’). Some vehicles also include torque converters to further lower the gearing.
Wheels or Tracks?
The choice between wheels or tracks comes down to cost and suitability, with tracked drivetrains being more expensive to produce and maintain than wheels. Wheels also provide a higher top speed, but tracks are better in difficult conditions.
Off-road vehicles will usually provide power to all of the wheels so as to maintain traction on slippery surfaces. This typically means four-wheel drive, although those vehicles designed to be used both on and off-road may allow this to be switched to two-wheel drive for road use.
While a lot of heavy equipment will use tracks to cope with severe service conditions, many heavy machines use tyres. These specialised tyres can be costly, with different categories for different uses, as follows:
Off-the-Road Tyres – Transport (for earthmoving machines), work (for slow-moving machines), and load and carry (for transport and digging)
Off-Highway Tyres – Compactor (C), Earthmover (E), Grader (G), Loader (L), Log-Skidder (LS) and Mining and Logging (ML)
These tyres have different tread types designed for hard-packed surfaces, soft surfaces and rock.
For recreational use, the tyres are split into those designed for all terrain (AT), those for muddy terrain (MT). There are also sand blaster and mud bogging tyres for more challenging terrains such as dirt, sand and even water, allowing the driver to maintain traction at extreme angles and high speeds associated with off-road motorsport.
What is the Difference between Green and Yellow Off Highway Vehicles?
Many OHVs are designed for construction or agricultural use. These two uses mean that these vehicles are commonly referred to as green (agricultural) or yellow (construction).
Yellow off highway vehicles refer to those used for earthmoving, and other heavy-duty construction tasks, while green off highway vehicles include tractors, combine harvesters and other common agricultural vehicles.
This simple colour differentiation comes because many traditional agricultural manufacturers (including John Deere) painted their equipment green while construction vehicles, like those made by JCB, are painted yellow. Of course, many of these vehicles are available in other colours, but these terms have stuck over the years.