Proof of the pudding All-new continuously variable transmission (CVT) will be an option for the first time on the Case IH Quadtrac, replacing the standard powershift. David Williams spent a day finding out how the new machine performs in challenging working conditions. For the largest high-horsepower tractors, powershift has been the accepted transmission, since technology progressed from standard gearboxes with manual clutch operation for gear shifting. Powershift allows shifting under load while clutch operation is controlled automatically, increasing efficiency and reducing operator effort. Early CVT offered advantages including infinite speed selection and ease of control, but lacked mechanical efficiency, so was best suited to operations where flexibility and ease of operation were more important than transmitting maximum engine power to the wheels. However, modern CVT is far more efficient, combining mechanical drive with hydrostatic, reducing power losses. Although full mechanical drive is most efficient for power
transmission; it lacks CVTâ€™s flexibility. Modern, electronically-managed CVTs constantly adjust the engine and transmission for optimal efficiency for any selected operating speed, compensating for the power efficiency losses in many situations. Higher work rates often result from greater ease of use and ideal speed selection, which is why many premium manufacturers offer transmission options including both types. However, Case IH is the first manufacturer to offer CVT in the Quadtracâ€™s size and power class. The new CVT transmission has four mechanical ranges, adjusted automatically, combining with hydrostatic drive to provide stepless speed control and constant drive. Mechanical drive proportion is up to 100 per cent, and never less than 50 per cent, maintaining efficient power
Controls are almost identical to smaller wheeled tractors in the range making it easy for operators to switch between them.
CVT allows the operator to set the working speed while the transmission and engine work together to optimise engine speed for maximum efficiency.
transmission at any travel or engine speed. Case IH developed the transmission with ZF, and it will be available only on Case IH machines for several years including Quadtracs and Steiger articulated wheeled tractors. Four models are available in CVX specification, but the two most powerful Quadtracs, with 580 and 620hp are currently available only with powershift.
as almost all machine operating parameters. The new Quadtrac was equipped with several new features including adjustable rate steering. Previously users complained that too many steering wheel rotations were needed during low speed manoeuvres and a new selector button reduces this by a third. continued over...
Ease of use A multi-function joystick, similar to that of smaller CVX models, provides precise speed control from stationary to maximum by moving it forward or back and it also houses buttons for direction change, hydraulic services, auto-steer and other programmable functions. Behind the joystick two sliding levers set engine operating parameters such as maximum and minimum speed and permissible droop under load. A foot pedal can also be used to control speed, even when the joystick is set. Whichever control is set for the higher speed takes precedence. A memory function allows an engine speed to be set and recalled at the touch of a button, while three separate travel speeds can be stored, displayed for quick reference on the cab pillar. The large touch-screen sets and monitors functions including field maps and auto-guidance, as well
The multi-function joystick, or foot accelerator pedal, select the travel speed while Automatic Productivity Management does the rest. Two throttle control levers behind the joystick are used to fine-tune engine operating parameters.
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