GA 1021 GM single rotor rakes

Detail from the KUHN GA 4321 gyrorake

For the most demanding raking operations

GA 4121 GM and GA 4321 GM single rotor rakes have MASTER DRIVE gearboxes, which are extremely reliable during intensive operations. The working widths of these machines are 4.10 m and 4.20 m respectivly.

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These single rotor rakes are as dependable as the larger models. Their MASTER DRIVE gearboxes are made to cope with the most intensive operations. In addition, they produce an impressive work output with their large working widths and the pivoting headstock, making easily manoeuvrable.
GA 4321 GM at work

Your benefits

As dependable as a larger model


MASTER DRIVE gearboxes

The rotor drive system is under a lot of strain during intensive raking operations. That's why KUHN developed a totally enclosed gearbox with the mechanical parts protected to reduce wear.
The MASTER DRIVE gearbox is renowned for its dependable design and exceptional longevity, even when used intensively.
It includes a double reduction system with a bevel gear and a cylindrical gear. Bevel-reduction tolerances are tightly controlled making the system extremely reliable and robust, even in difficult conditions.
Gearbox wear is greatly reduced and no maintenance is required. The double reduction system makes it possible to include larger cylindrical gears with more teeth for better power transmission.

Tines are made from heat treated steel

The tines rake the crop gently, even when it is heavy and dense. They are made of heat treated steel so their service life is optimised and resistance to fatigue is increased. The “floating” tine attachment, featuring three large-diameter coils, also reduces the risk of wear. Tine height is tightly controlled to preserve both the stubble and the crop.
Tines are made from heat treated steel

Great raking for clean forage, free of impurities

Optimum swath formation from the double-curved arms

Optimum swath formation from the double-curved arms

The homogeneous quality and the volume of swaths are necessairy for faster drying and easy pick-up by balers.
The tine arms on GA rakes are in a hyper-tangential position. This means that they reach a 90° angle very late. With the tines' sharp-angled cam, tine clearance is quick, later and requires little rotational effort to produce regular, fluffy and straight swaths. Raking is of high quality even at fast speeds because the forage is not pushed past the swath.
The advantages of double-curved arms:
  • They reduce the distance between tine passes. Forage loss is reduced, even at higher speeds.
  • The main weight is at the centre of the tine arm. This increases service life as it is not subject to pressure during rotation and the guide rollers are less subjected to stress.

Swath curtain

The swath curtain mounted on the frame, is easily adjusted by a handle. It can also be set from the tractor cab via an optional hydraulic cylinder. When extended outwards, the screen automatically moves to the rear, when retracted inwards, it moves to the front. This is very practical as it is always correctly placed in relation to the crop flow.
Swath curtain

Wheels are positioned to prevent crop contamination

The wheels are positioned extremely close to the rotor for improved ground contour following and to prevent the introduction of impurities in the forage.
Wheels are positioned extremely close to the tine arms for improved ground following

Stable on slopes

Headstock dampeners

Flexible pivoting headstock

GA 4121 and GA 4321 models are available with a pivoting headstock, which makes them as effective as a trailed machine.
At nearly 50 °, this coupling head offers the widest swivel angle on the market. Working on bends does not alter the raking quality or the shape of swaths so the baler has an easier job around corners

Work quickly and efficiently with bogie axles

To optimise ground speed, raking quality, preserve ground cover and protect the machine against wear and tear from uneven terrain, GA 4121 and GA 4321 models have another important feature: The bogie axle with four staggered wheels adapts to ground contours and keeps the machine stable during higher working speeds.
Bogie axles

Headstock dampeners

These single rotor models are equipped with one or more headstock dampeners to improve stability on slopes (standard on GA 4321 models, optional on GA 4121).
When lifting the rotor, the dampener automatically and smoothly centres the headstock behind the tractor
Headstock dampeners


GA 4121 GM at work


Technical characteristics

Working width (m)
Average windrow width (m)
Windrow deflector
Transport width with arms disconnected/connected (m)
Windrow delivery
Guard unfolding and folding
Control of the windrow curtain
Number of rotors / Rotor diameter (m)
Number of tine arms per rotor / Number of tines per tine arm
Tine arms
Bogie axles
Wheel type
Raking height adjustment
Tyres on each rotor
Headstock stabilisers
Theoretical tractor power requirement (kW/hp)
Road lights and signalling
Approx. weight (kg)
GA 4121 GM GA 4321 GM GA 4521 GM
4.10 4.20 4,50 (windrow to the right)
1.30 1.40 1,40
Windrow curtain Windrow curtain
1.75 / - 1.95 / - 2,20 / -
To the right To the right
Manual as standard - Hydraulic as optional equipment Manual as standard - Hydraulic as optional equipment Manual
Manual as standard - hydraulic in option
1 / 3.20 1 / 3.40 1 / 3,65
10 / 4 12 / 4 13 / 4
Removable Removable Removable
Fully enclosed double reduction MASTER DRIVE Fully enclosed double reduction MASTER DRIVE Fully enclosed double reduction MASTER DRIVE
As optional equipment As standard As standard
Fixed Fixed
Wheels adjustable in height by crank handle Wheels adjustable in height by crank handle
16 x 6.50 - 8 16 x 6.50 - 8 16 x 6.50 - 8
3-point Cat. 1 and 2 3-point Cat. 2 3 point Cat 2
Pivoting Pivoting Pivoting
As optional equipment 1 as standard, 2 as optional equipment As standard
22 / 30 22 / 30 26 / 35
As optional equipment As optional equipment
540 702 815