17 October 1997


Big M by name, big mower

by nature – Krones self-

propelled mower conditioner

seeks to satisfy the

contractors thirst for grass

cutting output that more

than matches the capacity

of a modern forage

harvester. Peter Hill reports

from behind the wheel of

this 300hp motor scythe

KEEPING in a straight line, while taking maximum advantage of the Big Ms 9.1m (30ft) cutting width, is the hardest challenge in mastering Krones new concept in self-propelled hardware.

With a trailed mower, all the driver has to do is steer pretty much alongside the uncut grass with gentle reaction from the tractor and mower to modest steering inputs. With the Big M, the driver has to contend with the more awkward characteristics of rear-wheel steering while keeping an eye on one of the mid-mounted mowers, which projects some 4m (13ft) away to one side and slightly behind the natural line of sight.

And all at up to a typical working speed of 19kph (12mph) without wasteful under-cutting or tell-tale tufts of unmown grass.

For a novice, it takes some getting used to; gluey strips on the side windows bear witness to a previous pilots attempts at making a sight guide. A driver with more opportunity to get some experience under his belt, or who has mastered a self-propelled forage harvester, will find things easier to manage.

The Big M certainly represents big potential for stepping up contract forage harvesting a gear or two. More especially, for trimming costs and meeting output demands.

Bernard Krone UK sales manager, Tony Hird, says contractors who have appraised the machine during a 1000ha (2500-acre) trial workload this summer like the idea of using one purpose-built, high capacity machine instead of two or three tractor-powered units.

The Big M will be expensive, he agrees, but the savings in capital investment, running and labour costs should still give it an advantage, he believes. Then there is the matter of work rate.

"Its not so much that contractors need to pack more work into a full day, than farmers wanting them to cut during a narrower window during the day when grass is in peak condition," he says. "To meet that demand, you need a machine of exceptional capacity to cut enough grass economically for the foraging team."

Slight overlap

With a trio of 3.2m (10ft 6in) disc mower conditioners – each with a slight overlap which produces the 9.1m (30ft) overall cutting width – and a 300hp Deere engine at its disposal, output is clearly what the Big M is all about.

"Wide mowing has been tried with tractor-mounted triple mowers and converted forage harvesters but not with a purpose-designed machine that has none of the speed or gear ratio limitations of the ad hoc devices," suggests Mr Hird.

Surprisingly, the ambitious project got underway in earnest little more than two years ago. Krones first use of simultaneous engineering, which brings all disciplines (design, manufacturing and sales) into the project together rather than consecutively, has proved effective at slashing development time.

Driving the Big M is certainly an experience. Cocooned in a cab in which drivers of John Deeres latest combines will feel instantly at home, and with the big volume Deere engine thrumming a little distance away, the operating environment is relatively quiet with a commanding view over the front mower and across to left- and right-hand mid-mounted cutting units.

The disc decks, complete with steel V flail conditioning rotors, are identical and a first for Krone in being driven from the centre. Its not difficult to imagine a centre-drive, swing-over trailed mower resulting from this particular aspect of the Big Ms development.

Individually driven

Each cutting deck is individually driven by a shaft and power band system such that any combination of front or mid units can be powered up.

Push-button mower drive engagement brings no drama at modest revs and with all decks in motion, the hand accelerator can be pushed fully home to bring them rapidly up to operating speed. Ground drive is hydrostatic, naturally enough, operated conventionally by a control lever through a forward/reverse gate.

Buttons on the control stick lift and lower each cutting deck individually or simultaneously; with the latter, there is a neat time delay for the mid-mounted units so they enter and come out of work at the right time.

The three ground speed ranges are rocker switch-selected in sequence; push once for 0-10kph; push twice for 0-20kph; three times for 0-40kph. With the last of those, the front wheel motors are by-passed so that enough oil is available at the rear wheels for a more than decent transport speed.

Same-size wheels and tyres are used all round – 600/55×26.5 Nokia Earthmoving & Logging Specials on the UK test model – which aim to meet the contrasting requirements of low ground pressure and durability. The Big Ms jiggly ride suggests they have to be pumped up fairish to carry its 10t bulk. Suspension would be a joy on this fast moving machine.

Tight turning rear-wheel steering, from a low ratio system that needs to be spun vigorously to get full lock, soon brings the machine round for a return run during an up-and-down mowing sequence or to effect a speedy loop turn when working round-and-round. &#42

Krones triple-deck self-propelled mower cuts a dash in grass remnants at Warwicks College, Moreton Morrell. Its for contractors who want a more productive mowing tool to match self-propelled forager capacities.

Big panels open to reveal the 300hp Deere engine, hydrostatic drive components and radiators for engine coolant and oil.


&#8226 Engine: 300hp Deere 6cyl turbo intercooled

&#8226 Chassis: Four equal wheels, rear wheel steering

&#8226 Drive: Three-range hydrostatic using Poclain wheel motors with diff lock anti-wheelslip function

&#8226 Mowing: Three 3.2m (10ft 6in) disc cutterbars overlapped to give 9.1m (30ft) overall cutting width; front unit suspended from trailing parallel linkage, mid-units attached at centres to lift arms

&#8226 Conditioning: Steel V flail conditioning rotors with 700-1000rpm speeds

&#8226 Drive: independent via power belts and shafts; mid-unit stow vertically for transport

&#8226 UK agent: Bernard Krone UK – Amazone Ltd, Harworth, Doncaster, South Yorks (01302-751200)

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