Case IH has taken its long-standing experience with CVT technology and produced a hydro-mechanical power splitting system for its tractors from 294kW (400hp).
It is now installed in selected models of Steiger four-wheel drives and Quadtrac full-size track tractors, and all three sizes of the Rowtrac, which is equipped with wide-spaced narrow tracks to operate in row crops.
This development brings the fine speed control and dynamic powertrain management strategies available in Maxxum, Puma, Optum and Magnum CVX tractors to the top end of the power and performance scale.
As well as delivering cost savings through improved fuel consumption, Case IH engineers say that CVT drive makes the tractors more user-friendly for operators of all skill levels, with extra features contributing to smooth operation and increased comfort for those behind the wheel.
But this doesn’t mean Case IH has ditched their traditional powershift with these latest articulated tractors because all are available with a revised mechanical transmission.
Now called PowerDrive, this uprated transmission is able to achieve 20% faster shifting for smoother operation, especially under relatively light load situations such as moving equipment between paddocks and travelling on the road.
The power shuttle also reacts more promptly, shifting between forward and reverse 38% faster and doing so with a smoother action.
Larger clutch packs and helical cut gears cope better with the highest power and torque outputs and help transmit the tractors’ copious muscle more efficiently.
Case IH engineers suggest the sum of these improvements can be a 5% reduction in power losses.
Automatic Productivity Management (APM) also has a role to play by monitoring the load on the tractor and shifting up whenever possible to allow a target ground speed to be achieved at lower engine revs.
Apart from enjoying a quieter ride, the operator could also see fuel savings of up to 24% over a conventional manually-operated powertrain.
PowerDrive remains the sole transmission available in the two most powerful models in the range – the 550 and 600 – where the 12.9-litre FPT engine delivers peak outputs of 452 and 493kW (614hp and 670hp). Both models are available in Steiger wheel and Quadtrac full-size track formats.
The new CVTDrive stepless transmission is reserved for models 400, 450 and 500, that produce peak power outputs of 328, 369 and 410kW (446hp, 502hp and 558hp) from the same engine, albeit using a single turbo whereas the two most powerful units have two-stage turbocharging to help extract extra performance.
It is available in all three Rowtrac variants and their Steiger and Quadtrac counterparts, as well as land scraper versions of the 450 and 500 models.
Although purpose-designed to channel power from the high mounted engine to the propeller shafts driving the front and rear axles, the CVTDrive transmission nonetheless follows the same principles of the units in other Case IH tractors.
There are four mechanical ranges, each engaged by its own multi-plate wet clutch pack attached to the planetary gear sets.
Ranges are shifted without interrupting the power flow and at the same speeds to provide almost imperceptibly smooth shifting without clutch wear.
The hydrostatic element varies ground speed within each of those ranges but never provides all drive so that a high level of mechanical drive efficiency – up to the four 100% peaks – is maintained for draft and heavy towing applications.
For each of the tractor models available with the new system, the merits of a continuous variable transmission apply.
Namely seamless and precise speed variation from just 1-metre/minute to 40kph; manual or automated speed adjustment on the go with no power interruption; and easier handling for the operator.
Selecting and setting the parameters for the most appropriate driving strategy for different applications demands a good knowledge of powertrain function and efficiency, that a skilled and experienced operator is best-placed to handle.
But an inexperienced operator will arguably find it easier to maintain performance once an operating mode has been set to suit a particular application.
Control can then be left to the electronic management system, leaving the operator to focus on the implement and the work it does.
By automatically balancing power and load, CVT-equipped tractors often deliver improved fuel consumption efficiency.
For ease of use, the operator can select one of three adjustable ground speed settings to suit headland turns before quickly returning to the chosen working speed; the third could be used for faster speed road travel.
The two-part throttle lever found on other Case IH CVTDrive tractors also features on the articulated machines to set droop and other engine speed limits.
A reversal of the powershift tractors’ decelerator pedal function is found on CVTDrive equipped tractors; instead of being used simply to slow the machine, it becomes a speed control or inching pedal on the stepless models so that very slow and precise manoeuvres can be achieved easily – such as when hitching implements.
Also, the Active Stop feature holds the tractor in the transmission’s ‘power zero’ configuration when it is brought to a halt on an incline, until the operator chooses to move off or until the service brake is applied automatically after 45 seconds.
A kick-down function rapidly drops the transmission ratio and builds revs to achieve fast acceleration but once a cruising speed has been achieved, the transmission ratio ramps up and engine revs can fall away to as little as 1640rpm at 40kph.
Optimum working speed is where significant productivity gains can be achieved, says Case IH engineers.
Instead of working to the fixed ratios of a powershift, CVTDrive provides seamless speed choice – and even a slight gain when multiplied over several hundred hectacres adds up to significant time and fuel savings.
As well, there is improved utilisation of capital equipment and labour.
Tillage, seeding, planting nutrient application with grain cart and other haul-out operations is where the most gains can be made.
Either through precision speed control or through rapid acceleration and auto speed adjustment.
Ultra-low speed specialising applications such as paddock drain tiling, scraping and ensiling forage crops can also be exploited using the benefits of CVTDrive control.
Features across the Steiger, Rowtrac and Quadtrac line-up still apply, including the four-point cab suspension, 40-deg right-turn swivel for the operator’s seat, and the Multi-Function control handle on the seat mounted console.
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