Kuhn five-furrow reversible plough Vari-Master L 5 NSH

Description and technical data

The five-furrow Kuhn Vari-Master L 5 NSH reversible plough is mounted in the three-point linkage of a tractor (category 3/4 N). Its total mass is 2,780 kg. Its work width can be set infinitely variably from 1.50 m to 2.75 m. The underbeam clearance is 80 cm. The plough had a hydraulic trip system, the so-called solid LPO mouldboards and maize skimmers.

The skimmer depth and angles are set with the patented Kuhn 3D-SKIM system (fig. 2) which helps burry the residues in a specific area inside the furrow.

There are four hydraulic lines, two of which supply the double-acting ram that turns the plough over, the other two lines supply the rams that adjust the depth and width, the first furrow width and plough angle. The rams are controlled from the KTS-10 control unit (fig. 3) which allows the operator to select the ram to be operated by the second spool. This means that all default settings are made from the tractor seat and with the help of scales that are clearly visible from the seat (fig. 4).

The only setting that is made from the ground is the point of draft which is adjusted with the help of a tool supplied.

The Vari-Master is marketed with a choice of three jockey wheels: the first is the combination wheel which runs alongside the beam and serves as depth control in the field and transport wheel on the road; the second is the rear-mounted jockey wheel which is exclusively a transport wheel; the third is the side-mounted jockey wheel for in-field depth control only.

The test plough had the side-mounted combination wheel. Figure 5 shows the plough in transport position. In this position, the wheel is rotated 90°, which is done with the help of a tool that is supplied with the machine. The top link is replaced by a chain which provides for sufficient travel between tractor and plough.

The lights are not removed for field work but are folded alongside the beam, a position in which they are protected from damage by two metal plates (fig. 6 and 7).

The operator’s manual is stored in a capped plastic tube on the headstock.

DLG test module “Functionality, quality of work”

In this module, the plough is field tested in line with the relevant DLG test framework. The measurements in this test take place in suitable test fields and are carried out at typical forward speeds and working depths. Before the test, the local conditions (preceding crop, soil type and soil moisture) and the weather are logged.

The plough is then set up in line with the local con­ditions. This is done after doing a number of trial passes during which the suitable settings the pre­vailing conditions are determined.

Match-ups, finish, trash incor­poration and the general quality of work are then assessed by five farming experts who assess the quality using the following scheme: very good (1), good (2), satis­factory (3), sufficient (4), not sufficient (5).

As the plough is put through the test, the testers log any blockages occurred, the quality of work along the edges and the furrow profile. The incorporation of crop residues is assessed by applying the grid method by VOßHENRICH. This method clears out a 30cm deep trench across the full working width, making sure to cut a smooth wall face. Then the area is sampled in 5cm-by-5cm grids, assessing and classifying the amount of residues incorporated in each square. The findings are illustrated in figure 8 which plots the biomass incorporation results with the help of different colours. A darker shade indicates a higher amount of straw in that particular grid.

DLG test module “environmental protection and sustainable resource management”

The “environmental protection and sustainable resource management” module assesses the lubricants used, the number of grease points to be attended and the type of bearings fitted as well as the draft requirement and fuel consumption which are measured with DLG equipment. The draft requirement is measured using the DLG-owned three-point linkage metering equipment. Forward speed and distance covered are measured with a Correvit L400 from KISTLER MESSTECHNIK. At the same time, the tractor’s fuel consumption is measured with the mobile DLG fuel consumption metering equipment. The machine’s nominal ha/h performance is computed using the actual forward speed measured and the work width.

DLG test module “Handling, ease of operation, service and maintenance”

This test module looks at the mechanical setting options for adjusting the working depth and width, the first furrow width, the tilt and the line of draft. Further details assessed to DLG schemes include the storage options for the hydraulic and electric lines.

Furthermore, farming experts carry out the service and maintenance jobs while the time taken is measured.

DLG test module “in-field performance”

The plough is operated on five different farms. At the end of each operation, the farmers complete a questionnaire that includes several questions on handling, ease of operation, service and maintenance and on the quality of work. Each question is answered to the following scheme: very good (1), good (2), satisfactory (3), sufficient (4), not sufficient (5).

Functionality and quality of work

The partial test on functionality and quality of work was carried in November 2021 in a plot of grain maize that had received a topping pass one week before the test and in a cover crop of perennial flowers that had received a topping pass three weeks before the test. The soil of the grain maize plot was loam (75 value points and 26.9 % soil moisture). The soil in the perennial flower mix plot was loamy clay (58 value points, 22.7 % soil moisture). The weather during the tests was sunny with light winds and temperatures between 9° and 14° C.

The plough was pulled by a Fendt Vario 722 (163 kW rated output and 168 kW maximum output at 2,100 rpm) that carried a 1,800 kg front weight in the front linkage .

The test involved creating one winter furrow (with maximum work width set to 2.75 m) and one seed furrow (work width set to 2.0 m) in each of the fields mentioned. In both fields, the depth was set to 27 cm and the forward speed was 6.2 km/h.
There were no disc coulters fitted. Not a single blockage was observed through the entire test.

Match-ups with the previous work, surface finish (roughness of the winter furrow, levelness of the seed furrow), incorporation of the biomass and the general quality of work were assessed by five experienced farmers who awarded mostly “very good” and “good” marks. The individual results are listed in table 5.

Table 5: Assessing the quality of work by five farming experts

Grading system: very good (1), good (2), satisfactory (3), sufficient (4), not sufficient (5)

The quality of work along the edges of the field depends on the selected work width. For example, with work width set to the minimal width of 1.50 m, you can work as close as 46 cm along a fence. Yet set the width to 2 m and this distance shrinks to 32 cm.

Figure 8 shows the results of the residue incorporation test. The biomass was incorporated at depths of 10 cm or deeper. Very rarely did the testers notice biomass that was left on the surface and not ploughed in.

The graphs in figures 9 and 10 plot the furrow profiles that were achieved with the work width set to 2 metres. Figure 9 shows the profile before the tractor wheels rolled on the furrow. Figure 10 shows it after the wheels rolled on it. (540/65 R30 front wheels, 650/65 R42 rear wheels). With work width set to 2 m, the nominal cutting width per share is 40 cm. Figure 9 suggests that only very little soil dropped back into the furrow. As the tractor rolls on the furrow, it compacts the soil and the furrow widens to approx. 70 cm (fig. 10).

Handling, ease of operation, service and maintenance

Assessment of machine handling

Work depth, work width, first furrow width and tilt are controlled from the cab-mounted spools after selecting the relevant function from the KTS 10 control unit. Each cylinder on the plough has its own scale for convenient adjustment. All these setting options were assessed as “very good” (++).

The line of draft is set up with the help of a tool that is supplied with the machine. Here, too, a scale helps resuming a previous setting. This setting option was assessed as “satisfactory” (o).

All hydraulic couplers are colour coded and the same colour code is repeated on decals on the headstock for easy sorting of functions and hoses. The hoses can be stored in a holder that is provided on the plough. A drip container is not available here. The hose holder and the colour codes are assessed as “good” (+).

The plough has a lighting system that is permanently installed and not removed for field work. Instead, the two bars are folded forward which brings the lights in a safe position. There is no dust-/waterproof storage position for the electric connector. The lighting system is assessed as “good” (+).

Table 6 lists the results on machine handling and set-up.

Table 6: Assessment of machine handling

* The evaluation was based on the DLG assessment schemes for tillage equipment

Service and maintenance times

The time spent on servicing / maintaining the plough was also measured in this DLG test. For this, all tools and parts required were provided next to the plough. The various operations are straightforward and require no specialist tools. Table 7 lists the results.

Table 7: Time required for service and maintenance and tractor attachment / removal

In-field performance

Five farmers in the Odenwaldkreis region near Frankfurt, Germany operated the plough in the period from 1 September to 15 November 2021, ploughing a total of 135 hectares of harvested grain, beans, silage maize and grain maize fields at work rates between 5 km/h to 11 km/h.

All five farmers find tractor attachment is good and very good. Adjusting the length of the stand is also good. The pipework is good. One farmer criticises that the oil lines are too long and at risk of tangling on the K80 hitch and tearing off. All farmers find that all components are manufactured to quality. Two find that the space between tractor and plough is very small. The advantage of this is that less weight is shifted off the front axle yet drawback is that there is not much room for coupling the plough.

More detailed results are listed in table 8.

Table 8: Results from the “in-field performance” test module

*    Grading system: very good (1), good (2), satisfactory (3), sufficient (4), not sufficient (5).

The farmers say that the plough is very easy to use. Setting up the plough to the field conditions always worked well. Soil penetration was good and the default depth was maintained accurately. The fact that the plough requires only two spools is given a great plus. Switching the hydraulic functions on the KTS box is also considered good. The plough can work very close to an obstacle or along and adjacent crop line, which is attributed to the jockey wheel being mounted centrally to the beam. The work width setting mechanism is integrated neatly in the beam. The setting options of the skimmers are considered favourable. Their depth is set conveniently by refitting a pin. Another advantage is the fact that the skimmers can turn towards and away from the ploughed land, which is useful to control the throw of the furrow slice. The damper on the depth wheel prevents the wheel flipping over during the turnover, which makes the process very gentle. In silage maize fields were game had been feeding on the crop, the plough ploughed the stalks in very well. No residues were found on the surface after the ploughing pass.

The farmers consider the number of 40 grease nipples (in full specification) as negative.

Changing the jockey wheel over into transport position is worth improving, because folding the jockey wheel and fitting a chain to replace the top link is cumbersome. One farmer finds a storage facility for the KTS box useful.

Some decals were damaged by the pressure washer. Two holding pins worked lose when ploughing in long maize stubble. Kuhn has addressed this and uses stronger pins now.

The paint coat on the beam was scratched by the vibrating lights when in work position; the Bowden cable that indicates the work width was damaged by scuffing on the stand. Kuhn has also addressed these issues and implemented modifications.