Capable of taking the rough with the smooth

All terrain vehicles (ATVs), have become an essential tool on many farms, particularly those involved with livestock or with long distances to be covered.

Today they are being used by an increasingly diverse market, with many utility companies, such as gas and electricity, using them to reach inaccessible areas. The army has adopted them as well: for example, the 1st Parachute Regiment is using them with its Rapid Deployment Unit to support foot soldiers by transporting equipment and weapons, and, in medical situations, to evacuate casualties. A dive being undertaken by the Scottish Institute of Maritime Studies is employing an ATV to carry supplies and equipment across rough and boggy ground.

ATVs owe their versatility to low ground pressure tyres which are inflated to between 2psi and 5psi giving a soft footprint and enabling them to cross water-logged ground without sinking, and to cross delicate, and valuable turf without damage. Alternatively the vehicles can drive on firmly-ploughed fields and rough terrain without riders losing control, as the suspension soaks up the bumps.

As far as Honda is concerned ATVs have been around since the 1970s, when its engineers developed a three-wheeled all terrain motorcycle (ATC). It was introduced with the American market in mind, and was aimed at the leisure industry, particularly for riding on sand dunes and in snow.

Vehicles first made their appearance in the UK in 1980. The following year the ATC200E was marketed as `the answer to your replacement tractor’. Immediately they were seized upon by the farming community which recognised their potential for a variety of tasks around the farm. ATVs were able to carry out chores that had previously been limited either to horses, ponies or larger 4×4 vehicles, such as Land Rover and tractors, or the job had not been tackled at all. They also enabled access to wet land earlier in the season than was possible with tractors.

The vehicles are popular because of the benefits they offer, such as mobility on unpredictable terrain. They can climb, help herd animals and reach outlying fields, and there is a variety of attachments which enable them to haul, spray and spread.

Now the biggest ATV produced by Honda has been introduced into the UK at the Royal Highland Show, Edinburgh, at the end of June.

It is claimed to be the most powerful and rugged ATV to date. The TRX450S and the TRX450ES use a compact OHV aircooled 432cc engine, specifically designed for use in ATVs. Rubber mounted for reduced vibration, the engine’s transverse alignment allows direct drive shaft connection to both the front and rear wheels, increasing power delivery.

F1 gear change

Previously seen in Formula 1 racing cars, a revolutionary push button gear change technology, known as Electric Shift Program (ESP), has been introduced on the TRX450ES. Mounted on the left handlebar, two buttons are used to change gears up or down, with no clutch or gearshift levers to worry about. It combines the ease of an automatic transmission with the positive action of a manual transmission.

The gear change lever has been replaced by an electric motor. At the push of a button, the electric shift motor will disengage the clutch, shift the transmission, and re-engage the clutch.

In order to make a smooth gear change and a smooth clutch engagement, the shift motor is controlled by a computer, known as the electronic control unit (ECU). This unit monitors gear change, engine speed and ground speed with information received from four sensors: the rpm sensor, which measures engine speed; speed sensor, monitoring the counter-shaft speed; change switch for the shift-drum position; and the spindle sensor for the shift spindle angle.

In common with other ATVs, the vehicle must be in neutral to start the engine, and it may need `rocking’ to change gear when the engine is off.

Once the engine is started the rider must change gears sequentially, pressing the buttons to shift through each gear in sequence, up or down.

The shift control motor also re-engages the clutch at different speeds, depending on how the rider is operating the machine.

The ECU calculates engine and transmission speeds and the ATV’s acceleration and deceleration to determine how the rider is operating the machine, from casual or normal riding to aggressive, sporty riding. Based on these calculations, the ECU will control the speed of the clutch re-engagement to achieve a smooth gear change, up or down.

Information received from the shift drum and shift spindle angle sensors, determines when the gear selection, either up or down, is complete and fully engaged.

If the gear dogs do not match up right away, the electric shift control motor continues to rotate the shift spindle for 70ms. The maximum time needed for the shift dogs to match and make full engagement is 34ms. This ensures a constant, smooth and complete shift.

The ESP system will not allow the transmission to be shifted from neutral to first or reverse gear when the engine is running about 3000rpm. This prevents sudden lurching. Neither will the system allow the transmission to downshift into neutral at any speed greater than 3km/h. This prevents `freewheeling’, and thus ensures that engine braking is always available while descending hills.

The TRX450S retains the usual foot controlled gear change, for its five forward and one reverse gear. Both have a low first gear said to provide excellent durability and towing capacity.

Both TRX450S and ES have 190mm ground clearance and are 1960mm long. They are the only ATVs to have a multi-function LCD display and improved cold weather starting, due to a carburettor electric heater system. Other features include a waterproof accessory socket providing a 12V power supply, and larger wheels and tyres.