22 December 2000

Stepless transmission offers smooth progress

John Deere claims anyone can operate its AutoPowr

stepless transmission which graced the Smithfield Show

machinery lines last month. Andy Moore put the unit

through its paces at the manufacturers Notts base

ASK most visitors about the highlights of last months Smithfield show and John Deeres latest AutoPowr stepless transmission will probably rank high on their list.

Designed for the 6410, 6610, 6810 and 6910 series tractors, the AutoPowr is said to have taken four years to develop as a joint venture between ZF and John Deere; ZF built the transmission, JD assembled the operating software.

The top three models can be specified with the transmission in 40K and 50K speeds, with the 6410 tractor eligible for a 40K transmission only.

"AutoPowr is best suited to the smaller 6010 series because the tractors are typically used for a wide range of applications including, spraying, baling and fertiliser spreading," says John Deeres Gordon Day. "Employing the transmission on larger series tractors would offer a smaller gain in productivity and operating efficiency due to the machines being used primarily for specific tasks such as tillage work."

Although other manufacturers offer stepless transmissions on tractors up to 260hp, Mr Day says there are no plans to fit AutoPowr on the larger 7010 and 8010 series machines.

farmers weekly paid a visit to John Deeres headquarters near Langar, Notts, where a test drive on a 140hp 6910 coupled to a 14t trailer gave the chance to put the stepless transmission through its paces.

Operators familiar with 6010 series tractors need not be daunted when climbing aboard models fitted with AutoPowr. John Deere has kept control layout almost the same, with no strange monitors or unusual gadgets.

In fact, for such a brainy transmission, AutoPowr is operated by only two main controllers – a power shuttle and a speed lever with an integrated speed wheel.

Unlike the existing shuttle used with JDs conventional transmissions, the AutoPowr shuttle offers forward/neutral/reverse positions, together with park and PowerZero work positions which are moved through an &#42 pattern.

Seated in the tractors TechCenter cab and with the 6.8-litre PowerTech engine purring, it is time to get the AutoPowr in operation by moving the shuttle into forward position.

From here, the operator can either move the speed lever to slow range one for field work, or range two which is more suited to fast forward speeds, such as transport or when turning on headlands. Both ranges can be programmed for required speeds and do not require the brains of a tractor technician to understand.

Pushing the lever into range two sets a red needle to 44kph (27.5mph) on the dashboards analogue display, designating the intended forward speed. This is the default speed which can be lowered or raised by using the speed wheel.

But with speed lever in transport position and shuttle lever moved forward, the 6910 fails to get off to a flying start – at first.

Like all transmissions, the operator has to set the engine revs, which is done by either a hand throttle or accelerator pedal.

Opening the throttle brings the PowerTech to its full 2600rpm chatter and we are off, with the AutoPowr transmission ratioing up to accelerate the 6910 up to 44kph.

The correct speed is confirmed by the white needle matching the red needle in the analogue display, before engine rpm automatically reduces to select the most economical transmission ratio and engine speed combination.

That gives the feeling that the tractor is losing power, but in fact the transmission maintains the correct speed.

The easiest way to reduce speed is to move the speed lever progressively down its slide, providing infinite speed adjustment. An alternative is to turn the speed wheel on top of the lever.

Although the wheel is intended for fine-tuning forward speeds in operations such as potato harvesting, it has no problem providing engine braking, reducing the transmission to 22kph in a few seconds.

Shift the speed lever up to transport position again and the tractor and 14t trailer rapidly recovers its 44kph, although a sharp stamp on the brakes brings the outfit to a grinding halt.

Less violent braking is achieved by shutting down the engine throttle and stepping lightly on the brakes, which causes the transmission to ratio down in progressive increments.

Back to square one and it is time to set up the transmission and engine to simulate ploughing speeds.

With the speed lever in work position, the speed wheel is wound until the needle on the analogue display points to 11kph and the throttle opened until the engine reaches 2000rpm.

The tractor accelerates smoothly up to this speed, but what about faster forward speeds when turning on headlands? Move the speed lever up its slide and the tractor quickens in pace, before moving it back to position one where ploughing can recommence at exactly the same engine and forward speeds. &#42

Main picture: John Deeres AutoPowr stepless transmission is available in 40K or 50K speed options for models in the 6010 range. Inset left: The AutoPowr shuttle offers forward/neutral/reverse positions, together with park and PowerZero work positions which are moved through an &#42 pattern. Inset right: The AutoPowr controls orange dog leg lever allows infinitely variable forward speeds which can be fine-tuned with the integrated speed wheel.


Engine 140hp PowerTech. Transmission 40/50K AutoPowr.

Hydraulics PFC. Weight 5.3t. Price 40K £63,779; 50K £69,740.

Engine 140hp PowerTech. Transmission 40/50K AutoPowr.

Hydraulics PFC. Weight 5.3t. Price 40K £63,779; 50K £69,740.