KEEPING ONE JUMP AHEAD OF THE FORAGER
KEEPING ONE JUMP AHEAD OF THE FORAGER
Second place in the complex category of last years
FARMERS WEEKLY/Barclays Bank Inventions Competition
went to farmer-contractor Brian Annings reverse drive mower.
Andrew Pearce ventured into Devon to find out more
IF youre a mower operator, being chased by a 380hp self-propelled forager concentrates the mind most wonderfully. It certainly did for farmer and contractor Brian Anning, especially back in 1996 when he was using a 3m (10ft) mower to fell 28-32ha (70-80acres) grass/day.
"I used to come home clapped out," he grins, "and thought to myself that there had to be a better way." And there was; a farm-built, twelve-drum, 24ft front-mounted grass gobbler, powered along by more than 200hp of Valmet 8750.
Mr Anning and his son Mike run a contracting business from Watchford Farm, Yarcombe, near Honiton. Cutting around 800ha (2000acres) of grass and 162ha (500acres) maize every year in a 10-12mile radius from base, they come across plenty of small, bumpy and steep fields. "I wanted to work faster with less strain," says Mr Anning senior, "But I didnt fancy a front/rear mower combination as they dont seem to last round here, and pollen and dust from the front one can lead to overheating. So that suggested reverse drive, which puts everything up front where you can see it and avoids a stiff neck. To cover the ground the machine would have to be wide, but there was nothing on the market to do the job.
"So I decided to put three 2.4m mowers together as a single unit. For this idea to work properly the beds must be pulled, not pushed; its the only way to let them ride up in work and follow contours. Experimenting with Meccano showed how the linkage and folding might work, so I went ahead."
* Arrowhead formation
Armed with just the idea, Mr Annning haunted various makers for two trailed- and one front-mounted mower bed. Only Westmac would supply, and after a cheque for £10,500 changed hands, a trio of 4-drum units arrived in early January 1997. "We laid them out on the workshop floor with 125-150mm (5-6in) overlap between the middle and outside ones, then worked out how to built the frame," Mr Anning chuckles. "And seeing all that moneys worth laying there, we wondered if we were doing the right thing."
His design puts the beds in arrowhead formation, with the front-mount one jutting ahead. Conditioners arent required as the Annings prefer to spread the crop with a second pass, then row it up for the forager.
A strong headstock carries a Waltershied gearbox – more on that later – and extends forward into a pivot for the central bed, which is lifted upward for transport by a long single-acting ram from an old McConnel P44 hedgecutter. To either side of the headstock cranked arms carry the two wing units. These arms pivot horizontally, letting short ex-McConnel double-acting rams fold the wings inwards for transport and thus bring width down to 2.8m (9ft). After folding, a mechanical link locks the wings in place.
Two things are central to the design, says Mr Anning. First, each mower bed is suspended from (and pulled by) the main frame, just as it would be in conventional trailed operation, with springs, adjustable links and wishbones allowing for float and pressure adjustment. The second key feature is the way tongues on the centre bed drop into slots on the wing units as the middle section lowers from transport. This arrangement locks the three beds together across their width, so forces trying to bend the wings in work are contained.
* Driveline
complications
The driveline caused a little head-scratching, at least until Mr Anning discovered Waltershieds GT60/40X box. "The mower needs a single central gearbox, with lateral shafts taking power to each wing unit," he explains. "So I had to find something that passed drive straight through to the middle mower, yet rotated its two side output shafts in the same direction – this is vital to make the wing beds knives spin the right way. Waltershieds box also shares power equally between all three output shafts, rather than passing it first through a single pair of gears. With over 200hp coming in, that helps reliability and greatly lessens the chances of the box breaking when one bed comes into the crop first."
Working out the drives took some thought. The middle unit was simple; its a standard front-mount device, taking power from the gearboxs straight-through shaft. Driveshaft spiders accommodate movement as the bed swings up through 90 degrees for transport.
The two wing units are standard trailed beds, designed to run on a tractors offside. Visualising how they were juggled into a reverse-drive setup might be easiest with a piece of paper and a pencil, but if you dont fancy sketching, try this. Put yourself in the reverse-drive tractors seat, and imagine a bed taken from its conventional working position and turned through 180 degrees. This one becomes the new mowers right-hand wing. As long as its input shaft is driven in the original direction, its knives will spin inwards in contra-rotating pairs as normal and produce two small swaths.
Arranging the left-hand wing was trickier. Simply reversing a standard unit and plonking it on the new mowers left flank would do the required trick of putting the beds intake side next to the crop, but leaves JFs standard drive pulleys stranded at the wrong end, away from the gearbox. So Mr Anning turned the bed around under its guards, bringing the input shaft up to the gearbox. This means the bed is pushed the "wrong" way through the crop, but it isnt bothered. All that was needed was to move JFs small swath-deflecting discs to the back (or they would be running in standing grass) and swap adjacent knife sets.
But wait a mo. Surely reversing the bed will reverse its drive, spinning the knives the wrong way? Not so, points out Mr Annning. Both gearbox output shafts turn in the same direction, so both bed shafts do likewise: consequently the left-hand unit cuts the same as its right-hand brother. The only other change was to move the left-hand beds driving pulley set to the opposite side of its driven set, improving gearbox-to-bed shaft alignment without changing rotation.
* In the field, on the books
Folding and unfolding takes around 10 seconds, or half a minute where roadwork involves using the transport lock. Before starting, the Valmets linkage is set at a height which leaves the beds plenty of room to rise and fall; then during work a single spool operates all six lift rams, bringing the mower very smartly in and out of work.
With 215hp recorded at the pto, the Annings Valmet isnt short of steam. Forward speed is generally 13km/hr (8miles/hr), with power in reserve for Devon hills and a three-step powershift on hand for turns. Workrate has shot up from the 7-8acres/hr of the previous 10ft setup to 20-25acres/hr, leaving six smallish swaths for the following 7m tedder to kick out. Narrow windrows are easy on tedder tines, points out Mr Anning, who finds the outfit rides easily and happily cuts forwards or backwards through existing swaths. Opening out headlands is a doddle, he says; its possible to drive right into a corner, back out and just swing into the new work.
Parts and materials for the new mower totalled around £13,000, with labour on top. "Less than adding a front pto and linkage to an existing tractor and buying another mower, and that still wouldnt work as fast or as easily," he says. So far 4000acres have fallen to the 24ft beast. Some weaknesses have showed up in the framework, but these will be dealt with by this coming campaign. The operator is happy and customers are too – so would the Annings go back to a conventional unit? "Never!"