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LAMMA 2021

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Keenan self-propelled mixer lands in UK

First shown at Sima earlier this year, Keenan’s first self-propelled diet feeder models are now heading out to UK farms. Richard Bradley caught up with one to find out more.

Self-propelled mixers do not come cheap, with Keenan's MechFiber 354SP costing £170,000.
Self-propelled mixers do not come cheap, with Keenan's MechFiber 354SP costing £170,000.

Known for its well-established range of trailed paddle-mixer wagons, Keenan says its first go at a self-propelled mixer allows farmers to increase efficiency through improved mixing times, consistency and reduced waste.


First shown at Sima earlier this year, the machine incorporates Keenan’s MechFibre paddle mixing tub with a self-propelled skid unit from Italian mixer-wagon specialist Storti, who has been producing self-propelled machines since 1967.

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To find out if Keenan’s machine is up to the daily grind performing one of the most important tasks on any livestock farm, we caught up with the first model to land in the UK on a Cumbrian dairy farm, a 16 cubic-metre capacity MechFibre 345 SP.


To give us full details on the skid-unit, Matteo Borsaro, Storti’s technical product manager ran us through the machine, along with Keenan’s UK sales manager James Brough.

Milling head

Milling head's 84 knives are arranged in separate banks, which the firm says minimises forage destruction.

The biggest step away from a conventional Keenan mixing tub is the machine’s hydraulically-driven 1.8m wide milling head. It features 84 knives (42 straight and 42 curved) to cut and lift crop away from the clamp face and can reach to a maximum height of 5.25m.


Arranged in separate banks rather than a continuous chevron pattern, as used with most other machines, Mr Borsaro says how fibre destruction is minimised. “As modern silages are often cut short, you have to be careful not to break them down further, so we designed our milling head not to shred the crop.”


Both milling head and transfer conveyor can be reversed. For milling silage and picking up concentrates, pellets or other materials from the floor, the head rotates forwards. If you do manage to block the head, or to provide additional chopping for dry materials such as haylage, the head can rotate backwards.

Milling head leaves a well sealed clamp face which should help to reduce secondary fermentation.

Adjustable rollers and a scraper plate prevent the milling head from digging into the ground, and allow the machine to neatly clear the floor. To load small volume minerals, a hatch is fitted to the loading arm and a safety switch on the arm must be held for the conveyor belt to take the minerals into the mixer. While possible to tip the bag and press the button at the same time, it does take a little bit of skill.


When loading, an audible warning is used once near to desired weight for each ingredient, at which point the rotor and conveyor can be stopped quickly by buttons on the joystick. This should offer accurate loading, especially when compared to tipping materials in with a telehandler bucket.


Available as an option, a near infra-red sensor can be mounted just behind the milling head, which analyses the dry matter of the crop in real time as it is milled from the clamp face, and can adjust required ingredient amount to maintain overall ration dry matter. This, according to Mr Brough should help to maintain a more consistent diet over each mix, as he says clamped silages can vary massively.


While the head left a compact and well-sealed face behind, the milling head guard tended to drag on the clamp when raising the arm to make another cut. Allowing it to pivot back further may solve this minor niggle.

Mixing tub and discharge

At the heart of the self-propelled mixer is Keenan’s MechFibre paddle-mixing tub. Featuring two-banks of three paddles, the tub is effectively split into two sections, with a series of fixed knives along the base of the tub – number of knives can be specified to requirements.


Mr Brough says: “The milling head compliments our tub, as it pre-chops material without totally shredding it, and the tub gives a gentle mixing action, again reducing destruction of forage.”

Unloading to the left provides best views, it can cause some issues however.

As with all Keenan paddle mixers, a discharge auger runs the full-length of the mixer to discharge the mix onto a front-mounted cross conveyor, which can side shift about 150mm in either direction.


Taken from the firm’s trailed mixer range, the tub has simply been rotated 180 degrees placing the drive system at the rear for maintenance access, and the discharge auger down the right-hand side. Unfortunately, this means if the conveyor is shifted to the left for clear views during unloading, some material can completely miss the belt and be spilt on the floor as it exits the auger on the right hand side.


To remedy this, we think a re-shuffling of the tub may be required, with the tub rotated so the discharge auger is on the left, and drive relocated to the rear. For additional simplicity, Keenan says it is looking to offer its traditional chute-style unloading system, rather than a conveyor. This should also reduce overall machine length a little.

Engine and drive

Power comes from a 4.5-litre, four-cylinder FPT engine. Stage 4 emission regulations are met via the use of diesel exhaust fluid, and while its maximum 168hp is not met until 2,200rpm, its 712Nm of torque is available down at 1,500rpm, much closer to the recommended milling and mixing speeds.


Connected directly to the engine is a single-speed transmission to drive the mixer’s paddle and unloading auger, with drive transferred to the tub’s main chains at the rear via three pto shafts.


Mounted to the front of the transmission two larger and one smaller variable displacement Bosch Rexroth hydraulic pumps look after hydraulics. The larger two pumps seperately look after drive to milling head and wheel motors, with the latter smaller pump looking after all other elements such as conveyors and arm raise and lower.


Its standard two-speed hydrostatic transmission offers a 0-15kph range and faster 0-25kph range. When moving around the yard and especially for unloading, the transmission allows you to easily vary forward speed to suit desired feed-out rate. Transmission control is simple, thanks to a two-pedal setup with one for forward and another for reverse.

Running gear

Despite its near 10m length, the Keenan SP is surprisingly nimble with a much shorter wheelbase.

The machine uses Storti’s shorter wheelbase platform. This is handy around the yard, with farmer Mr Brough commenting how the mixer turns much sharper than you would imagine, however, the bus-like overhang at the front does take a little getting used to, he says.


Unlike other machines on the market, this mixer is only currently available with two wheel steering at the front. While options may be looked into, Storti stands by this design at the moment, and says steering rear wheels when loaded up would likely cause excessive tyre wear.


Standard running gear comes from a hydro-pneumatic setup for front wheels to help take out shocks caused by moving the cutting head around, and the rear wheel motors are fixed to the chassis. If road work is common, the firm offers a 40kph transmission option, which benefits from a suspended rear axle. Even with its fixed rear axle, the machine travelled around undulating yards well, with the front end coping fine with any small bumps.

Cab and controls

Controls are relatively intuitive, an armrest would be a nice feature however.

While incorporating a few creature comforts such as air conditioning and an air-suspended seat, the cab remains relatively basic and should stand up to some wear and tear.


Movements for main arm and its parking stand are looked after by a main console-mounted joystick, which features two buttons to look after milling head and transfer conveyor. Four lights are used to indicate direction of travel for both systems. A second lever engages cross-conveyor drive and opens/closes a door on the feed-out auger. Both joysticks are proportional, and while the main joystick falls easily to hand, an optional armrest would be a nice addition for a little extra comfort.


Switches to change transmission ranges, engage tub drive and open the milling head’s guard are dotted around the right hand console and steering column, and a small digital display is used to indicate engine speed, door position, and fuel level.


Also inside the cab is a screen to view the standard rear-view camera and up to two additional ones, which could be a welcome addition to provide better views to the right-hand side. Keenan’s InTouch control box is also mounted in the cab, to display remaining weight to load or feed out.


Despite its large price tag, Keenan says self-propelled machines can save money in the long run in reduced machine purchase cost. There are also greater long-term benefits for livestock from consistently producing an accurate ration, according to the firm.


To prevent a large initial outlay, the firm is offering the machines on a contract-hire terms over a number of years, which can also incorporate a servicing to give owners additional peace of mind.

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