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“Dahu”: a tool for vineyard cultivation

 “Dahu”: a tool for vineyard cultivation

Since our first meeting with the winegrowers of St Joseph in the Ardèche (south east France) in August 2014, the project of designing a cultivation tool for work on sloping vineyards has moved forward considerably.

The request came from winegrowers cultivating on sloping who had get off their tractor after each pass in order to adjust their machinery. The idea was to design a tool able to work on two half rows of grapevines, which could adjusted without getting off the tractor.
The name “Dahu” refers to an imaginary wild mountain animal with long back legs and shorter front legs, and was chosen because of the tool’s adjustable depth wheels.

June 2014: an initial design proposal

The initial design put forward consisted of a fixed frame, with a 30cm sliding extension bar on either side of the frame, each carrying:

  • a flat double disc (300mm in diameter), adjustable from an angle of -45 degrees to 45 degrees (depending on the volume of soil and where it wants to be shifted) and adjustable with a hydraulic jack
  • possibility of having spring tines in front of discs to loosen up the soil
    idea of incorporating comb weeders onto the frame to weed around the grapevines (1m in diameter)- not yet designed
  • a series of tines to level the soil, hoe around the foot of the vines and maybe remove some new shoots
    pivot mounted depth wheels fixed on the frame, with the height manually adjustable and the direction controlled by a hydraulic jack.
    finger harrows on the back of the frame to help aerate the soil.

Meeting on 28th August 2014:

  • an articulation on the lift arms of the tractor is needed to ensure uniform cultivation on uneven ground
  • the combination of discs, finger harrows and comb weeders should avoid the creation of a furrow next to the row of grapevines or along the grass row
  • the depth wheels need to penetrate into the soil- it was decided to opt for a sharp serrated disc sandwiched between two discs of a smaller diameter.
  • due to the varied widths between the vine rows within one plot (and sometimes along a row) an automatically retractable frame is , although it involves a complicated and expensive design
  • as no hydraulic hoses should enter the tractor cabin, electrical commands are needed to direct the jacks
  • the soil can be compacted due to previous wet weather passes, so it might be necessary to mount tines in front of the discs
  • a modification of the frame needs to be developed to widen the span of the extension, allowing the frame to have a smaller width when folded

Construction of the pre-prototype in Autumn 2014 by Atelier Paysan to test a series of implements (spring tines, serrated flat disc, articulated comb weeders, finger harrows)

Pre-prototype test- 25th November 2014

Summary of the CAD design so far:

Notes on the tool:

  • Use wider discs (45cm) and/ or use curved discs
  • Increase the diameter of the finger weeders to 60cm and allow for the angle of the tool to be adjusting depending on the ground level
  • More flexible comb weeders, and add adjustment for the depth of the combs
  • We will test without the use of sensors
  • Mount the entire frame onto a slider system (triangle and depth wheels included) in order to be able to shift the frame from left to right and avoid knocking into vines.
  • Study a lifting system for the tool to manoeuvre it more easily at the end of the rows

Changes introduced:

  • The frame is made of 2 U-shaped plates onto which the tools are fixed. The U-shaped tool bars are fixed onto a central frame.
  • The articulation between the lift arms and the frame gives an increased lifting capacity (controlled with a hydraulic jack) and offsets the tool
  • Adjustment for the depth and angle of the comb weeders
  • Adjustment for the lateral and longitudinal positions, height and direction of the harrow

End of February 2015: Prototyping phase (in Valence)

Feedback on the tool and improvements:

  • the depth wheels cannot direct the tool as they are too close to the tractor -> we will add a large wheel at the back and in the middle of the frame, directed by a hydraulic jack (previously used for the depth wheels). The depth wheels are still included in the design, but not the penetrating disc
  • the direction of the frame span is difficult to control manually: the proposal of sensors was reintroduced. The sensors control the opening and closing of the frame automatically-> the sensors were fitted but there were problems with the hydraulic lift system. A sensor was added at the back of the frame to limit the extension of the U frames.

The adventure continues…

The tool is still in its testing phase, which is why we have not yet published the designs. If you want to follow the project, visit the forum: http://forum.latelierpaysan.org/viewtopic.php?f=171&t=3045


Technical drawings of the Dahu

Warning! The tool needs to be tested before its design is validated!

Creative Commons

The entirety of this article, including descriptions, photos and technical drawings, are available for all to use under a Creative Commons licence. They can be distributed and modified as long as the user mentions their origins (Atelier Paysan) and ensures that all related tools and documents are also under Creative Commons.