Flagship forager has big build for handling bulk

5 November 1999

Flagship forager has big build for handling bulk

Reputed to be the worlds

largest forage harvester, the

Case Mammoth 8790

purports to be in a class of

its own. Andy Moore reports

MAMMOTH by name, mammoth in stature. Cases flagship 8790 forager would appear a cut above its former Mengele-produced sibling range.

The line-up, which includes the 480hp 4800, 420hp 7400 and 370hp 6900, marks the first entrance by Case into the self-propelled forage harvester market following their launch at Smithfield last year.

While the main selling point for the 540hp 8790 rests on its huge capacity, the model also features several design improvements on the three smaller foragers.

"A drawback with the other machines is the design of the crop passage. Material such as dry grass travels at a steep angle over the cutting cylinder which may sometimes causes blockages," says Nigel Worthington of Case. "Another difficulty is converting the machines from grass to maize harvesting, which has to be performed manually outside the machine and can be a time-consuming task."

Case has addressed both issues by fitting the 8790 with a re-designed crop flow system.

Thanks to a repositioned concave, grass now flows more freely in a straight line underneath the chopping cylinder instead of over the top.

Conversion from grass to maize harvesting can now be adjusted electronically using in-cab switches which activate a hydraulic ram to pull the corn crackers clear of the feed passage.

At the front of the machine, the forager features an improved header coupling system and hydraulic, rather than belt-driven, feed rollers.

"Using hydraulic drive on the feed rollers not only eliminates inefficient running gear, but allows infinitely variable speed control and therefore chop length," says Mr Worthington.

Behind the rollers, the 8790 is equipped with a wider 800mm (31in) cutting cylinder, fitted with 24 instead of 48 knives – arranged as a chevron to increase crop throughput.

farmers weekly travelled to Somerset to look round the demonstrator machine – rain put paid to a hands-on test drive.

Circling the 6.75m (22.5ft) long Mammoth gave the opportunity to peak underneath the machines barn door-sized bonnets.

Opening the left bonnet reveals the 540hp V8 Mercedes twin-turbocharged engine which is now crossflow mounted instead of in the transverse position.

Swallowing up an average-sized man, there is ample room for delving inside for clearing fan blockages or close-up service checks on the engine.

To the left of the engine and positioned level with the chassis is the fuel tank which holds nearly one tonne of fuel.

The back of the Mammoth gives way to main service points such as sight glasses for hydraulic oil levels, filters and access to the main control valves.

Mounted on the side of the block are the hydraulic gear pumps which drive the feed rollers and the machines hydrostatic transmission – a three-range Claas gearbox. Maximum forward speeds in each range are 10kph, 16kph and 40kph respectively.

Lifting the right-hand panel exposes the rotary radiator screen, which can be opened up to reveal, in the following order, air conditioning unit, oil cooler and engine radiator.

With all items opening out like pages of a book, Case has clearly thought hard about keeping maintenance tasks as simple as possible.

After fitting all panels firmly back in place, the next port of call was the Axial-Flow type combine cab which is reached by climbing a set of vertical steps.

The spacious cab offers a good vantage point to monitor each side of the six-row maize header and, in the run of things, an equal advantage for a 3.2m grass pick-up.

Joystick control easily moulds to hand and is worked fore and aft to control speed/direction – with main buttons responsible for operating header raise/lower, discharge spout, and roller direction.

Both the joystick and a bank of rocker switches float up and down with the seat. Main rocker switch functions include header fold, spout up/down, corn cracker roller distance and two engine speed controls – 2000rpm and 1750rpm.

A downside to the cab, however, is the three-speed range lever which is tucked rather awkwardly away behind the shoulder of the operator.

Mounted on the right-hand cab pillar is the 8970s in-cab computer which can be raised or lowered to suit the operator.

On the master display, engine temp/revs, roller/cylinder/forward speeds and the distance between the cracker rollers are recorded.

Clearly a machine built to achieve some impressive results in terms of output, the Mammoth should find favour with contractors looking to expand their business opportunities.


Engine: 540hp twin-turbocharged V8 Mercedes.

Transmission: Hydrostatic three-range.

Feeder system: Hydraulically-driven four feed and compression rollers; chop length infinitely variable up to 17mm.

Chopping mechanism: 800mm wide chopping cylinder with 24 knives; three-roller corn cracker system.

Harvester options: Maximum 3.2m grass pick-up and eight-row maize header.

Price: £146,780.

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