THE Case IH Optum CVX slots into a relatively new category for tractors that breach 300hp in a package big enough to put the power down, but small enough to provide the manoeuvrability needed for handling trailers and other towed equipment.

Just as fertiliser spreading used to be the preserve of 80-100hp tractors, but is now frequently undertaken by machines in the 200hp class, so haulage and other jobs once exclusively handled by those tractors are in the wheels of bigger, heavier, more powerful machines.

With fewer operators driving bigger tractors handling wider tillage and drilling equipment to gain economies of scale, so equipment for transport, spreading and spraying are being up-scaled to match the capabilities of those power units. So, 'more power and close to Puma dimensions' was the target for Case IH engineers in devising the Optum CVX, which has a 6.7-litre NEF engine from FPT Industrial in two models.

This is tuned to extract 270hp and 300hp at a rated speed of 2100rpm, maximum power of 288hp and 313hp available at 1800rpm for all operations - there is no additional boost for pto or transport work, in other words.

Emissions are handled by FPT's latest generation SCR system for European Stage IV/US Tier 4 Final compliance, while a single electronically-controlled variable geometry turbo pumps up the torque at lower revs and is said to spool up quickly for sharp responses.

A 630-litre fuel tank should keep the tractor supplied through a day's work, especially since measures such as an idle speed management feature trims revs from 850 to 650rpm after a short period standing still.

According to the DLG PowerMix test - a combination of real-world field and transport activities - operators of the Optum CVX can anticipate fuel consumption in the order of 249 g/kWh.

Changes to the engine for its installation in the Optum include new valve material and design for the cylinder head to handle a higher combustion pressure, although the main change is evident in the lower part of the engine, where the oil sump forms part of the chassis of the tractor to avoid undue stress being transferred through the engine block.

While they typically weigh in at 11 tonnes, this structural sump contributes to an allowable maximum gross vehicle weight of 16 tonnes, so there is plenty of scope for carrying heavy implements or adding ballast to gain traction.

In the transmission department is a beefy version of CNH's stepless transmission, which switches pretty much seamlessly between four gear sets to provide a 0-50kph speed range and four points of optimum efficiency combining mechanical and hydrostatic drive.

The Optums run on the same front axle as the smaller Magnum tractors, with hydraulic suspension by two cylinders providing 110mm of vertical travel for added driver comfort and max traction over a rough field surface. The cab and mudguard installation allows fitment of 2.15m diameter tyres - such as a 710/75 R42 - to help get the power down on what is a relatively mid-range wheelbase of 2995mm.

Hydraulic resources reflect the different roles this tractor is likely to undertake. A 165-litre/min piston pump system is standard, but tractors destined for high-demand air seeders and the like can be upgraded to a 223-litre/min pump.

Both automatically respond to flow and pressure demand so minimise wasteful pumping when demand from implements and on-board systems is modest.

Optum CVX tractors likely to spend much of their time on the front of trailers, tankers or spreaders can have the added security of ABS to promote safer braking.

Also novel is the two-speed gearing for the front pto when fitted. A control knob in the cab selects either of the two speeds - 1000rpm and 1000rpm eco - the latter providing a fuel-saving opportunity to run the engine at a slower speed for implements that do not require full power.

Similar principles apply to the four-speed pto at the rear of the tractor, where the three-point linkage is rated at 10,299kg to the full extent of its lift range and 11,048kg to a lesser height.