CVT brings knobs and features fresh to drivers of conventional transmissions. Here’s a round-up the terms used in this test.
Engine load control.
This determines how far engine revs can fall before the transmission starts to gear itself down. One extreme of adjustment usually delivers max power, where revs fall only a little before gearing starts to drop. The other produces max economy, where revs can sink a long way before gearing lowers.
The first mode holds the engine at or near its point of maximum power, and the second (usually called eco mode) lets the engine work in an area of lower specific fuel consumption. Between extremes, the driver can choose a mix, as between position and draft.
Most modern eco systems go further, monitoring engine torque in order to match revs to demand; for example, varying rpm according to draft load during ploughing. Draft load goes away at headlands, at which point a good eco setup lets revs sink right down to balance the new, lower requirement. This saves fuel, saves wear and makes for more relaxed operation.
Decides how sharply or gently the tractor reacts to a request for speed change.
Stops the tractor rolling on a slope without using the brakes, by locking the transmission hydrostatically. A big plus in work.
Basic or stick mode.
Driving by joystick movement. Push the stick forward to go forward, pull back to slow, stop or go backwards. Engine revs are varied conventionally by hand or foot. In basic mode, the tractor drives like a stepless powershift.
Driving by pedal. Now the foot throttle becomes a driving pedal – push more to go faster. Revs and gearing are matched automatically to the load and the driver’s demand. Direction reversal is by conventional shuttle.
A way of storing one or more target speeds for immediate recall. For instance, when ploughing with a tractor having three cruise memories, you might set one cruise speed for work, a slower one for headland approach and a slower one still for headland turning.
The tractor will try to reach and hold each target speed once the relevant memory is triggered. Depending on where the engine load control is set and how closely the engine and transmission control systems are integrated, engine revs and gear ratio will be juggled automatically to maintain cruise speed as conditions change.