Vehicles and the protection of the environment are often deemed to be in direct opposition. This opposition is normally levelled at emissions but sometimes in other ways. The use of vehicles in environmentally sensitive areas is often the cause of concern - this is to some degree unjustified. It will depend on the type of vehicle and its suitability to the particular conditions as to just how much `damage' it will or may cause.
The ground pressure (the weight that the vehicle or even person or animal imposes upon the surface), if high, is probably the major cause of damage. Traction, or more importantly the loss of it, is also very important. A vehicle travelling easily across ground without wheel slip and or sinkage is not likely to cause damage. As soon as wheel slip occurs or the wheels create ruts due to high ground pressure or a combination of both, then lasting damage can occur. Worse still if the vehicle becomes stuck. High ground pressure that is not necessarily obvious can cause compaction beneath the surface which can interfere with plant root development and drainage. Multiple passes along a particular route of vehicles, people or animals can create major problems. Cross country routes, tracks, footpaths can soon become compacted, worn, rutted and even impassable. A specialist vehicle with low ground pressure - perhaps the same or lower than that of a human foot, can travel over very soft and difficult terrain with minimal disturbance. It may be better able to vary its route than more conventional vehicles so reducing the development of tracks and the problems associated to multiple passes.
There are a number of specialist vehicles as well as modifications available to more conventional vehicles that offer low ground pressure. However it does not stop there. The ability of the vehicle to traverse the terrain - often difficult - in safety and without becoming stuck or getting wheel slip is also very important. A stuck vehicle can create quite a mess particularly during recovery which may involve a much heavier recovery vehicle. A vehicle with all wheel drive has a much better chance than one that has not. Four wheel drive vehicles (even some of six and eight wheels) are generally high ground pressure and ultimately have limited ability. Many of the specialist vehicles operate on tracks which do offer low ground pressure but tracks are not always very kind to the ground surface particularly when turning by 'skid steer' as the majority must. Many of the multiwheeled low ground pressure vehicles that can be used either as tracked or wheeled vehicles are also skid steer. The act of steering causes the vehicle to break traction. This not only introduces a sideways skid to a greater or lesser degree but often promotes wheel spin on the other set of wheels. If the vehicle is loaded which it probably is, there will be greater resistance to turning and therefore more effort required to achieve a turn so increasing the opportunity to cause surface damage, especially on soft surfaces. Also compounding this problem is if the vehicle is asked to tow a load - normally a trailer. The trailer must also be on low ground pressure tyres. If towed by a skid steer vehicle, be it on tracks or wheels, the trailer will have a tendency to oppose the turn, especially if it is heavy or on an up hill climb. This again promotes a loss of traction.
The Supacat 6x6 answers most if not all of these problems. It has genuine low ground pressure using six high floatation, wide section tyres, run at very low inflation pressures. In general ground pressure is assessed by adding the internal tyre pressure and the tyre carcase `pressure' together. In the case of the Supacat the tyre carcase pressure is about 1 psi. The operating pressures are variable according to the conditions but would normally range between 3 and 8 psi. A human has a ground pressure of around 5 psi. The drive system of the Supacat offers a true 6x6. It is a `full time' six wheel drive with all three wheels on each side of the vehicle mechanically connected so that no one wheel can `spin out'. A single differential divides the drive to each side but this too is controllable by independent brakes so that any tendency for the wheels on one side of the vehicle to spin can be prevented. This can be done in opposition to the direction of steering - something that is impossible on a skid steer only vehicle. This gives the Supacat an excellent tractive performance and very precise and accurate control over what the wheels are doing.
The steering system is unique. Of the six wheels, the front four steer conventionally (Ackerman), the centre pair steering 50% of that of the front pair so reducing to a minimum any scuffing of tyres or the surface of the ground. The conventional steering is backed up by the independent brake steer system. This can be used to steer the vehicle if required, to increase the vehicle's manoeuvrability over and above or in conjunction with the conventional steering as well as to control traction. This steering system allows the Supacat to be quite at home on hard surfaces - not the case with skid steer only vehicles. On very soft marginal surfaces again the Ackerman system has the advantage. By not having to break traction and so possibly the surface to steer, the Supacat has a much better chance to preserve the integrity of the surface and therefore its ability to support the vehicle and provide traction to propel it along.
The Supacat has a substantial load carrying capacity and with well designed trailers can tow an equal load or more. The dual steering system making the Supacat a very able towing vehicle.
For exceptional situations - normally deep snow or extremely boggy conditions the Supacat can be fitted with tracks. This will of course introduce some of the operating problems previously discussed and so in general the wheels would normally be used if at all possible. However the Supacat can be fitted with a `half' track system. This offers benefits of both systems. Tracks are fitted around the middle and rear wheels leaving the front wheels free to steer the vehicle. The brakes may be used to back up the conventional steering as if it were on wheels only. This system offers most of the benefits of tracks while retaining the advantages of conventional steering for on and off road operations.
The need to access and work on environmentally sensitive areas is ever increasing - so is the desire to preserve them. This may be to repair mountain footpaths worn away by thousands of walkers, it may be to repair or construct power or pipe lines, to reach and operate on the shoreline for coastal defence or to clear pollution, it may be for leisure, forestry or agriculture, or for rescue work. Perhaps to patrol high security installations or carry out search and rescue operations. The MOD operate ranges which are often remote and environmentally sensitive - Supacats have been operating on these for many years and in some cases are the only vehicles allowed on the area. The needs may be principally environmental or economic - reinstating damaged ground can be expensive. Helicopters which are sometimes the only option are very expensive and weather critical. The area of operations does not necessarily have to be a remote moorland or high mountain to justify the need for a machine that can work with minimal ground damage. The electricity supply industry for example has to access agricultural and other managed land where damage to crops and the ground itself is unacceptable. This can either severely limit the times when work can be carried out or introduce high costs of reinstatement having caused damage to the work site and access route - which may not be acceptable to land owners and environmentalists.
Whatever the end use the Supacat 6x6 offers a practical solution to mobility. The conditions may be difficult or not so difficult and may or may not be environmentally sensitive. The Supacat is capable of carrying and or towing a very substantial load of personnel, goods or equipment, even when the going is particularly tough. It is able to work on poor ground conditions that would normally be unacceptable for a vehicle to operate on.
The Supacat offers an answer to an ever increasing problem - that of an acceptable means of useable mobility in environmentally sensitive situations.
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