Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01D—HARVESTING; MOWING
  • A01D41/00—Combines, i.e. harvesters or mowers combined with threshing devices
  • A01D41/12—Details of combines
  • A01D41/14—Mowing tables
  • A01D41/141—Automatic header control

Definitions

• the invention relates to a forage harvester of the type defined in the introductory portion of claim 1.
• a forage harvester makes it po'ssible automatically .to keep the height of the cutting head above the ground and thus the stubble height essentially constant, ir ⁇ respective of irregularities in the surface of the ground.
• the US Patent Specification 2 750 727 discloses a forage harvester of the present type, where the ground engaging means are formed by slide shoes mounted on a rotatable shaft.
• An adjustable link mechanism connects this shaft to an arm which, in one embodiment, can be caused to contact one or the other of two contact means and thus actuate an electric motor to raise or lower the cutting head, and which, in another embodiment, actuates a hydraulic valve inserted in an oil line which shunts a hydraulic cylinder- to raise and lower the cutting head, thus varying the oil pressure in the cylinder and thereby the height of the cutting head above the ground.
• the object of the invention is to provide a forage harvester of the present type whose height adjusting mechanism is more sturdy and can thus cope better with the tough working conditions to which it is subjected than the prior art ones, and which moreover responds more quickly to irregularities in the surface of the ground than the prior art height adjusting mechanisms.
• the forage harvester is constructed as stated in the characterizing portion of claim 1 since, in this structure, pressure sensing and control of the height adjusting mechanism take place without any use of moving members, viz. by means of a firmly mounted strain gauge, which moreover responds instantaneously to any change in the pressure of the ground engaging means against the ground.
• Claims 2 and 3 define various possibilities for the mounting of the strain gauge, and simple embodiments of the means for controlling the height adjusting mechanism, when this is formed by a hydraulic cylinder, are defined in claims 4 and 5.
• fig. 1 is a schematic side view of an embodiment of the forage harvester of the invention, coupled to a tractor,
• fig. 2 is a section along the line II-II in fig. 1, and
• fig. 3 is a diagram of an electric -hydraulic control system.
• the numeral 10 designates a forage harvester in the form of a windrower which is coupled to a tractor 11.
• the windrower has a cutting head with a beam 12 suspended between two gable members 20; the beam rotatably mounts a plurality of disc-shaped cutters 13, here four, which are caused to rotate in a generally known, not shown manner during travel.
• the windrower has two ground wheels 14 mounted on the outer end of their respective pivot arms 15.
• a hydraulic cylinder 16 is mounted between each pivot arm and the frame of the windrower to raise and lower the windrower with respect to the wheels.
• Each cylinder is connected with an oil/air accumulator 17 mounted directly on the cylinder.
• FIG. 1 shows a strain gauge 21 placed on the top side of a slide shoe 18, and, in response to any change in the pressure of the slide shoe against the ground, the strain gauge applies an electric signal depending upon the size of the pressure change.
• the strain gauge 21 is connected to an amplifier 42 with two outputs, which are in turn connected to electromagnets in their respective ones of two magnet valves 43 and 44. These valves, when actuated, connect the cylinder 16 with an oil supply conduit 32 and a reservoir 35, respectively.
• the amplifier 42 is so arranged as to actuate, upon actuation of the strain gauge- 21 in one or the other direction from an average state corresponding to the desired pressure against the slide shoe, one or the other, respectively, of the two magnet valves 43 and 44 with a view to supply and discharge, respectively, of oil to and from the hydraulic cylinder to raise and lower, respectively, the cutting head until the desired engagement pressure has been re ⁇ established.
• the magnet valves 43 and 44 may be either cut-off or regulating valves.
• the details of the shown and described structure may be varied in many ways. As examples of readily performed changes may be mentioned that the shown relatively narrow slide shoes may be replaced by two disc-shaped shoes, each of which extends approximately half the width of the machine. Also wheels may be used instead of slide shoes. Moreover, instead of a single strain gauge, two might be used, which are actuated upon deviation in their respective directions from the desired average state of the deformable machine member. The strain gauge might also be placed on other machine members than a slide shoe, e.g. as shown at 22 in fig. 2 on one of the gable members 20.
• An additional possibility is the mounting of the cutting head in the' frame in such a manner that the head is movable vertically by means of the hydraulic cylinders, instead of moving the entire machine frame up and down.
• the hydraulic cylinders might be replaced by other forms of height adjusting means, e.g. mechanical jacks driven by electric motors whose power supply is controlled by the amplifier 42.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Environmental Sciences (AREA)
• Harvester Elements (AREA)
• Led Devices (AREA)
• Magnetic Resonance Imaging Apparatus (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8117264

Family Applications (1)

Country Status (6)

Cited By (14)

Families Citing this family (1)

Citations (3)

• 1984
  • 1984-06-15 DK DK293184A patent/DK293184A/da not_active Application Discontinuation
• 1985
  • 1985-06-14 AU AU45439/85A patent/AU4543985A/en not_active Abandoned
  • 1985-06-14 WO PCT/DK1985/000059 patent/WO1986000002A1/en not_active Application Discontinuation
  • 1985-06-14 EP EP85903229A patent/EP0186696A1/de not_active Withdrawn
• 1986
  • 1986-02-07 FI FI860575A patent/FI860575A0/fi not_active Application Discontinuation
  • 1986-02-14 NO NO860555A patent/NO860555L/no unknown

Patent Citations (3)

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