12 April 2002

Seamless gears to

perfect bale

As with others of its kind,

John Deeres AutoPowr

stepless transmission is an

intriguing technical

development. But does it

offer practical benefits for

its higher price? To find

out, Mervyn Bailey talked

to one of the first owners

JOHN Deere 6010 series tractors were already available with a multitude of gearbox options when the AutoPowr stepless transmission was added a year ago. Claimed to give greater efficiency and improved work rates, AutoPowr is a hydro-mechanical gearbox developed by ZF using Deeres own control system.

It allows the driver to move seamlessly from stationary to full speed without crunching through gears. And by choosing one of the three transmission modes – manual, economy or power – drivers can tune engine and drive characteristics to make full use of the tractors potential.

To operate the tractor, the driver selects the required forward speed and direction of travel, then simply presses the accelerator. The transmission does the rest, changing through the range gears automatically.

Mark Westaways John Deere 6610 AutoPowr performs an important role for his Paignton, Devon-based horse feed business. The 115hp tractor joined the rest of the Love Lane Farm fleet earlier this year and so far has clocked up 350 hours. It shares the more demanding jobs with a 6600 and together they mow and bale a total of 445ha (1100 acres) of grass. The 6610 AutoPowr is mainly used with a conventional square baler producing forage bales, which are processed into Horse Hage, a low dust feed for horses.

"Forage quality and baling consistency are the two main points we have to focus on to obtain a high standard of feed," says Mr Westaway. "The AutoPowr tractors transmission enables the operator to monitor the baler and regulate forward speed very precisely according to swath density, and thereby produce a close to perfect bale."

The infinitely variable gearbox was not the only reason for choosing the 6610 AutoPowr over other models. Mr Westaway acknowledges the benefits of the electronically governed fuel pump. Although not as fine-tuned as the system fitted to a mechanical gearbox tractor that used to perform this work, he reckons it is better than on other variable transmission tractors he has tried.

"As well as offering precise ground speed control, the tractor keeps a constant output at the power take-off," comments Mr Westaway. "This is important because otherwise there is a change in plunger timing which is something we want to avoid."

This feature is also useful for other jobs such as mowing or ploughing, which impose variable draft loads. The engine and gearbox work together to prevent the motor dying down.

Choosing the 6610 AutoPowr was not an easy option as the tractor has many operations to perform. For baling it would be possible to get away with 100hp but due to the undulating Devon landscape it is best to be slightly over – rather than under-powered, notes Mr Westaway.

As the tractors role was not as clear as it is now, it was fitted with a Lynx front linkage and power take-off. It was once thought that if the tractor was unsuited to baling it could be used as the mower tractor. As it is, the 6610 AutoPowr spends five months baling and only occasionally does some mowing with a front/rear mounted combination.

However, there has been a notable improvement in output when used for this task. Partly because the 6610 has a 5hp advantage over the 6600, but largely due to the transmission, which has enabled average forward speed to be increased from 8km/hour to 10km/hour.

"This is because the tractor speed is easy to adjust so there is no need for the driver to select a lower than ideal gear just to save having to make frequent changes," notes Mr Westaway. "But there is a downside, in that the 6610 AutoPowr uses a bit more diesel than the 6600 while carrying out the same jobs."

A five-leg Shakaerator soil loosener and four-furrow reversible plough make good use of the tractors extra weight and traction. If it is a bit light on the nose, extra ballast is added in the form of a concrete weight attached to the front linkage.

"The 6610 has good power to weight ratio and is ideal for our purposes," says Mr Westaway. "While a 6910 is too big for our current requirements, it would be nice to have more power for the first cut grass as the tractor is sometimes a little underpowered and overheating can be a problem."

His tractor drivers find the AutoPowr easy to operate, as the remainder of the tractor is similar to the other 6000 series machines already used on the farm. Most have used the AutoPowr model at some point and all agree that, in contrast to some continuously variable tractors, it is relatively simple to operate.

"Most of the drivers have been able to sit in the AutoPowr and perform every day tasks and the designated driver was able to use the tractor to its full potential after just a couple of days work," comments Mr Westaway.

This particular model is fitted with front axle suspension and for baling the driver cannot praise this enough.

"When youre baling for five months of the year with a conventional baler that tends to shake the tractor, it is nice to have something that will dampen it to an extent," says Lloyd Stone, main driver of the 6610. "I like the AutoPowr gearbox, too. It gives you just the right speed which makes it possible to do a quick turn round at headlands as you can just speed up and slow back down very easily."

Mr Westaway adds: "The AutoPowr transmission has done everything the sales man said it would. It will definitely be in the running when we upgrade the mowing tractor in the near future." &#42

Mark Westaways John Deere 6610 AutoPowr is used in conjunction with a conventional square baler for five months of the year and so far has clocked up over 350 hours.

AutoPowr control lever is used to move between two different speed bands set by the driver using a thumbwheel that can also be used to make fine speed adjustments on the move.

Quality forage and consistent bales are the two main points we have to focus on to obtain a high standard of feed," says Mark Westaway.