GB1562337A - Rotary harrow - Google Patents

Description

(54) ROTARY HARROW (71) We, ISHIKARI ZOKI KABUSHIKI KAISHA (ISHIKARI MACHINE MANUFAC TURING Co., LTD), of 737-7, Yura, Kurisawa-machi, Sorachi-gun, Hokkaido, Japan, a Japanese Corporation, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a rotary harrow.

According to the present invention, there is provided a rotary harrow comprising a rotor formed by a plurality of spaced plates mounted on a horizontal shaft and carrying a plurality of elongate blades each arranged to extend continuously along substantially the entire length of the shaft, the cutting edges of the blades lying on a cylindrical surface coaxial with the shaft and being arranged to engage soil with a predetermined angle of attack, there being further provided means for controlling the depth of penetration of said rotor into the soil and levelling means arranged behind said rotor for levelling the soil after treatment.

The invention will now be more particularly described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a rotary harrow; Figure 2 is an end view of a similar harrow; Figure 3 is a partial elevational view of the rotor of the harrow shown in Figure 1: Figure 4 is a side view of the rotor of Figure 3: Figure 5 is a partial elevational view of an alternative form of rotor.

Figures 1 and 2 show a rotary harrow which is hauled by a tractor (not shown in the drawings). The rotary harrow is connected with the rear of the tractor by means of an upper link 1 and lower links 2, and is so constructed as to receive motive power at a bevel gear transmission device 4 at its centre through the intermediary of a universal joint shaft 3. Said gear transmission device 4 is attached to a machine frame 5 having end plates Sa atits ends between which two beams Sb are mounted, the housing of said gear transmission device 4 being fixed by bolts on a square plate Sc supported between said beams 5b. Between the lower parts of said end plates 5a is supported a rotor shaft 6. To an end of said rotor shaft 6 is attached a driven sprocket (not shown in the drawings) of a chain transmission device 7 installed at an end of the machine frame 5, and motive power for rotation is received through an endless sprocket chain from a driving sprocket (not shown) installed on a transmission shaft 8 extending from the gear transmission device 4 towards the chain transmission device 7.

Said rotor shaft 6 is provided with discs 9 of, for instance, approximately regular hexagonal shape adjacent said end plates Sj, as seen in Figures 3 and 4, and also with a number of similar discs intermediate said end plates 5a. Six soil-crushing blades 10 with their edges lying on a cylindrical surface coaxial with the rotor shaft 6 extend between respective corners of said discs 9 with the edges of the blades directed outward. The attachment of each soil-crushing blade is so regulated that its edge has a rake angle x and a relief angle P with respect to the tangent to said cylindrical surface as shown in Figure 4.

Behind the rotor is located a levelling plate 11 for levelling soil surface after treatment by the rotor, and gauge wheels 12 for adjusting the depth of cultivation are provided in front of the rotor. Said gauge wheels 12 are carried on arms 12a which are supported by means of bolts inserted in any of several holes bored in upper and lower rows in the front parts of the end plates 5a to allow for adjustment of the gauge wheels 12.

A rotary harrow with such a construction is moved forward by rotation of the rotor shaft 6 by means of motive power to be transmitted from the power take-off shaft of the tractor through the universal joint shaft 3 to the gear transmission device 4 and further therefrom to the chain transmission device 7.

If, at this time, an appropriate advance speed and an appropriate rotating speed of the rotor shaft 6 are maintained, soilcrushing blade 10 can scrape off soil layers in flakes rake the flakes of soil into the rotor and throw then out behind. The levelling plate 11 thereafter passes over the soil so as to level off the cultivated soil surface.

The penetration of the soil-crushing blades 10 into the soil is sufficient for the rotary harrow not to float up due to resistance of the soil, and swift soil crushing can be carried on with maintenance of desired cultivation depth. Further, by virtue of the rake angle and relief angles of the blades 10, caking of soil lumps on the back surfaces of the blades is avoided.

In the embodiment shown in Figure 5, soil-crushing blades 10 are of helical con figuration. Therefore, the point of penetration of each soil-crushing blades into the soil gradually shifts from one end to another so that a large impact is not imposed instantaneously on each blade, but rather the load on the rotor due to soil resistance remains approximately constant.

The above described rotary harrow can be used for the cultivating of paddy fields, and also for soil crushing in fields of relatively hard soil, since the penetration of the soil-crushing blades into soil is thorough.

WHAT WE CLAIM IS: 1. A rotary harrow comprising a rotor formed by a plurality of spaced plates mounted on a horizontal shaft and carrying a plurality of elongate blades each arranged to extend continuously along substantially the entire length of the shaft, the cutting edges of the blades lying on a cylindrical surface coaxial with the shaft and being arranged to engage soil with a predetermined angle of attack, there being further provided means for controlling the depth of penetration of said rotor into the soil and levelling means arranged behind said rotor for levelling the soil after treatment.

2. A rotary harrow according to claim 1 wherein said blades are straight and extend parallel to said shaft.

3. A rotary harrow according to claim 1 wherein said blades are helical.

4. A rotary harrow according to any preceding claim wherein said plates are of approximately regular hexagonal shape and carry six blades.

5. A rotary harrow according to any preceding claim wherein said means for controlling the penetration depth of said rotor comprise a pair of gauge wheels adjustably mounted in front of the rotor for contact with the soil surface.

6. A rotary harrow according to any preceding claim wherein said transmission system is connectable to the power take-off shaft of a tractor and comprises a universal joint shaft coupled via a gear transmission device to a transmission shaft extending parallel to and above the rotor shaft, said transmission shaft and said rotor shaft each carrying respective sprockets connected by an endless chain.

8. A rotary harrow substantially as herein described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (1)

1. **WARNING** start of CLMS field may overlap end of DESC **.

   and lower rows in the front parts of the end plates 5a to allow for adjustment of the gauge wheels 12.

   A rotary harrow with such a construction is moved forward by rotation of the rotor shaft 6 by means of motive power to be transmitted from the power take-off shaft of the tractor through the universal joint shaft 3 to the gear transmission device 4 and further therefrom to the chain transmission device 7.

   If, at this time, an appropriate advance speed and an appropriate rotating speed of the rotor shaft 6 are maintained, soilcrushing blade 10 can scrape off soil layers in flakes rake the flakes of soil into the rotor and throw then out behind. The levelling plate 11 thereafter passes over the soil so as to level off the cultivated soil surface.

   The penetration of the soil-crushing blades 10 into the soil is sufficient for the rotary harrow not to float up due to resistance of the soil, and swift soil crushing can be carried on with maintenance of desired cultivation depth. Further, by virtue of the rake angle and relief angles of the blades 10, caking of soil lumps on the back surfaces of the blades is avoided.

   In the embodiment shown in Figure 5, soil-crushing blades 10 are of helical con figuration. Therefore, the point of penetration of each soil-crushing blades into the soil gradually shifts from one end to another so that a large impact is not imposed instantaneously on each blade, but rather the load on the rotor due to soil resistance remains approximately constant.

   The above described rotary harrow can be used for the cultivating of paddy fields, and also for soil crushing in fields of relatively hard soil, since the penetration of the soil-crushing blades into soil is thorough.

   WHAT WE CLAIM IS:

   1. A rotary harrow comprising a rotor formed by a plurality of spaced plates mounted on a horizontal shaft and carrying a plurality of elongate blades each arranged to extend continuously along substantially the entire length of the shaft, the cutting edges of the blades lying on a cylindrical surface coaxial with the shaft and being arranged to engage soil with a predetermined angle of attack, there being further provided means for controlling the depth of penetration of said rotor into the soil and levelling means arranged behind said rotor for levelling the soil after treatment.

   2. A rotary harrow according to claim 1 wherein said blades are straight and extend parallel to said shaft.

   3. A rotary harrow according to claim 1 wherein said blades are helical.

   4. A rotary harrow according to any preceding claim wherein said plates are of approximately regular hexagonal shape and carry six blades.

   5. A rotary harrow according to any preceding claim wherein said means for controlling the penetration depth of said rotor comprise a pair of gauge wheels adjustably mounted in front of the rotor for contact with the soil surface.

   6. A rotary harrow according to any preceding claim wherein said transmission system is connectable to the power take-off shaft of a tractor and comprises a universal joint shaft coupled via a gear transmission device to a transmission shaft extending parallel to and above the rotor shaft, said transmission shaft and said rotor shaft each carrying respective sprockets connected by an endless chain.

   8. A rotary harrow substantially as herein described with reference to and as shown in the accompanying drawings.