Kuhn freshened up its plain mower offering in 2024 with the introduction of the rear-mounted GMD3515. We paired it with the GMD3125F last season.
KEEPING IT BRIEF
- Mowing performance was decent under all conditions.
- Weight distribution is good, even without adding weights.
- Smooth surfaces make cleaning considerably easier.
- A GMD3123F lists at £18,805 while the GMD3515 is £18,890.
With the cost of diesel back in the spotlight, all farmers and contractors will be seeking to boost efficiency. A plain front and back mower set-up could tick that doing- more-with-less box — less horsepower and more hectares per hour. In fact, over the years we have looked at several simple mower set-ups, and the latest to get the profi Practical Test treatment is Kuhn’s new GMD offering, the 3151 and 3123F.
The rear-mounted 3.5m wide 3151 is the smaller of the two models in the GMD1015 series; the other is the GMD4015, which covers 3.95m on each pass. A key feature of these mowers is that they fold vertically over-centre for transport. We will dive into the other details shortly.
Compact push
Meanwhile, the 3123F is a one-model range as a simple front-mounted mower with the sleek nose cone shroud. The 3123F hitches directly to the tractor’s linkage rather than using an A frame. The Cat II headstock is fabricated from sturdy round tube. A sliding frame allows the mower to pivot up and down by 12° on rubber buffers.
Pressure relief is achieved with coil springs and chains that attach to the tractor.
Proven tools
Power is transmitted to the front mower through a Bondioli and Pavesi pto shaft. A right-angle gearbox splits the power to the right where it meets another right-angle gearbox that sends the drive downwards to the OptiDisc Elite cutterbar.
A metal brace, which supports the mower against the frame and reduces any sway, compensates for all the extra weight of the gearboxes on the right side. The cutterbar is mounted on rubber blocks connected to the frame which noticeably reduces vibration and noise.
This 3.0m bed has seven discs, each with two blades. On our test machine, the two outer disc units on each side were equipped with top hats to direct the cut forage toward the middle. These are complemented by an adjustable swath disc on each side to ensure the cut forage is reliably deposited between the wheels, even on tractors with narrower track widths.
Although this design can’t compete with the ground-following prowess of a pulled front mower, we still thought the pushed 3123F did a very acceptable job of adapting to the contours during our test.
Short in length
Although the mower is relatively short, we have come to appreciate the optional front mirrors (£295). The manually folding side guards also work very well: you first push the guard out of its locking position and then fold it up — folding it back down is just as easy. If you don’t want to leave the cab, then for an additional £945, the guards can be folded hydraulically.
For smaller tractors
Kuhn introduced the new-ish GMD3515 rear-mounted mower for the 2024 season. It is aimed at farms that want to achieve high mowing efficiency with a relatively modest sized tractor.
The Cat IIIN lower link coupling points have two mounting positions offset by 20cm, allowing the overlap with the front mower to be adjusted to suit your conditions. Like the front mower, drive is transmitted using a Bondioli and Pavesi shaft, with the power making its way to the cutterbar via a pair of bevel gearboxes.
The 3515 needs both a single-acting and a double-acting spool. The single-acting valve looks after lifting the mower at the headland and, after using a diverter, also adjusts the LiftControl relief system, with the current pressure shown on an easy-to-see gauge on top of the headstock.
Folds up compactly
The double-acting line is responsible for folding and unfolding the mower; because it shifts over centre to 125° in its transport position, it needs a double-acting ram. A throttle valve helps regulate the oil flow, which is handy if this is not easy to do or possible on the tractor itself.
When folded, the mower is just 2.65m wide; and its height, with the lower links still in their field work position, is less than 4.0m. It is also well balanced when on the road.
Plenty of space and safety
A sturdy arm supports the beefy centre pivot OptiDisc Elite eight-disc bed. A small hydraulic cylinder helps to keep the raised mower balanced when turning on the field headland. Kuhn’s brochure stats state 20° upward travel and a 15° downward travel. We certainly didn’t have any issues here during the test season.
It is also very easy to set up. There are two helpful arrows: when these are aligned, the lower linkage height is correct. The mowing height is adjusted as per usual by altering the length of the top link. The standard skids allow a stubble height of between around 40 to 70mm; Kuhn also offers two types of high-cut skids (45-85mm and 85-120mm).
If the lift arms are correctly positioned, then more than 30cm of ground clearance remain below the lowest point of the raised mower cutterbar, which should ensure most swaths stay untouched when crossing. Kuhn has designed the cutterbar’s NonStop impact protection and the relief mechanism to be hydraulically operated.
Clean cut
The eight-disc rear and seven-disc front OptiDisc Elite mowers cut cleanly under all conditions. Even lighter, wet autumn grasses or dry, stemmy stuff were cut without any noticeable stripes. The rear mower lays down the cut grass across almost its full width.
We primarily operated this front and back combination with a Fendt 516 Vario and a John Deere 6155R. The weight distribution worked well on our mostly flat fields. When in work, the left rear wheel is relieved of 440kg, while the right wheel is loaded with 1,580kg (measured with the mowers on the Fendt 516). If you need to, then there is the option of adding up to 360kg of counter- weight (including the mounting bracket), which will set you back £1,250.
Easy parking
Integrated parking stands on the 3515 let you store it in its folded position, so it takes up less shed space. It also features a very helpful mechanical locking mechanism that securely connects the headstock and the boom, eliminating the need to reset the pressure relief valve to zero each time the mower is taken off. This is something we soon learned to appreciate when frequently taking the mower on and off.
Summary
The GMD3515 is a simple yet high output mower. Hitching on/off and adjustment are all straightforward.
The GMD3123F front mower model is equally simple in design. Together, the two machines deliver good results. The weight and centre of gravity were well-balanced on the test tractors.
The rear-mounted mower in test configuration is priced at around £20,140, while Kuhn charges £18,805 for the front-mount GMD.
Christian Brüse
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