GB1597122A

GB1597122A - Lawn cultivating machine

Info

Publication number: GB1597122A
Application number: GB1088678A
Authority: GB
Original assignee: BIELEFELDER KUECHENMASCH
Current assignee: BIELEFELDER KUECHENMASCH
Priority date: 1977-03-26
Filing date: 1978-03-20
Publication date: 1981-09-03

Description

(54) LAWN CULTIVATING MACHINE (71) We, BIELEFELDER KUCHEN MASCHINEN-U. TRANSPORT GERATEFABRIK VOM BRAUCKE GmbH. of Meierfeld 14, 4800 Bielefeld 1,.

Germany, (Fed. Rep.); a German body corporate, 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:- The present invention relates to a lawn cultivating machine having two parallel cutter shafts connected together by a transmission gear, the shafts being rotatable about their axes, a plurality of cutters being provided on each of the shafts at spaced intervals from one another, the cutters on one shaft being displaced relative to the cutters of the other shaft.

The surfaces of lawns, with increasing age, tend to become covered with moss.

Bulky layers of slowly rotting parts of plants may also be formed on the surface of the lawn, whereby the topmost layer of the soil becomes compressed. Layers of moss and the like restrict the growth of the lawn, so that it becomes thin, uneven and unsightly.

In order to prevent this development, it is known to scarify the lawn, whereby the soil is traversed and loosened on the surface, utilising knife-like blades. A customary implement for this is a scarifying rake which is drawn over the lawn. Since the individual blades execute an uninterrupted cut in the soil, a large amount of force is necessary.

This treatment has the further disadvantage that there is the risk of pulling too many lawn plants out of the soil.

The present invention seeks to provide a machine by means of which moss, and other bulky layers, can be carefully extracted from the lawn and by means of which the soil can be ventilated and loosened in a simple manner.

According to the present invention there is provided a displaceable lawn cultivating machine comprising two parallel cutter shafts which are connected together by a transmission gear arrangement, the cutter shafts each being rotatable about a horizontal axis, each axis being at right angles to the direction of displacement of the machine, a plurality of cutters being arranged at spaced intervals from one another on each of the shafts, the cutters mounted on one shaft being off-set relative to the cutters of the other shaft, both cutter shafts, in use, rotating in the same direction, the transmission gear arrangement being such that the rate of rotation of the leading, in the direction of travel of the machine, cutter shaft is caused to be less than the speed of rotation of the rear cutter shaft.

The cutter shafts are preferably mounted on a common frame. The machine may be manually- or motor-driven and may have a yoke-shaped handle portion.

It is preferable for the cutters to be circular discs having teeth projecting radially from the circumference thereof.

Alternatively, the cutters may be circular discs having teeth projecting from the circumference thereof at an angle to the radial direction. The teeth of the cutters lying at the rear, in the direction of travel of the machine, are preferably inclined rearwardly relative to the radial direction, whilst the teeth of the forward cutters are inclined forwardly.

It is preferable for the transmission gear to be a chain drive, a chain wheel being secured to each cutter shaft and the chain wheels being enclosed by a common chain.

The chain wheel of the rear, in the direction of displacement of the machine, cutter shaft preferably has a smaller radius than the chain wheel of the front cutter shaft.

The transmission gear may be arranged in the central region of the cutter shafts.

Alternatively, two transmission gears are provided, one transmission gear connecting corresponding ends of the cutter shafts, the other gear connecting the other ends of the cutter shaft, each gear being provided with free motion.

It is preferable for at least one of the two cutter shafts to have a stripper plate or cleaner mounted on the frame associated therewith, the teeth of the cutters projecting into slots formed in the stripper plate. Both cutter shafts are desirably provided with a common stripper plate which may be located between the cutter shafts and extend parallel thereto. It is advantageous if the stripper Plate is mounted on a shaft extending parallel to the cutter shafts and which is held in an end position by a spring.

The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 shows a perspective view of a lawn cultivating machine according to the present invention.

Fig. 2 shows a longitudinal section through the machine according to Fig. 1; Fig. 3 shows the arrangement of a stripper plate on the frame of the machine; Fig. 4 shows a plan view of a machine with the transmission gear arranged in the centre; Fig. 5 shows a plan view of a machine with transmission gears arranged on both sides.

A lawn cultivating machine in accordance with the present invention comprises, as shown in Fig. 1, two cutter shafts 11 and 12 mounted in a frame 10, said shafts being connected together by a transmission gear 13. Secured to the cutter shaft 11 are a plurality of cutters 14 and secured to the cutter shaft 12 are a plurality of cutters 15, the cutters in each set 14, 15 being equally spaced apart from one another. The cutters 14 on the cutter shaft 11 are off-set relative to the cutters 15 on the cutter shaft 12. The shafts 11 and 12 are parallel to one another. In this manner, soil 16 (Fig. 2) to be treated is efficiently broken up. The top surface of the soil is, of course, covered with a layer of grass.

The lawn cultivating machine may be manually operated by pushing or pulling by means of a yoke-shaped handle 17.

However, it is also possible to drive the machine by means of an electric motor or an internal combustion engine.

As shown in Fig. 5, the cutter shafts are connected at both of their ends by transmission gears 18, the housings of which gears are secured to the ends of a centre shaft 19. The housing of the transmission gears 18 and the shaft 19 form a frame 20, which frame replaced the frame 10 shown in Figs. 1, 2, and 4. In the embodiment shown in Fig. 4, the gears 18 are again provided but are instead mounted on the central region of the shafts 11 and 12. The gears 18 are, in this embodiment, still connected to the central shaft 19. The shaft 19 acts as a mounting for a stripper blade 21 (see Fig. 4) or for a stripper blade 22 (see Fig. 5). The stripper blade 21 or 22 is provided with slots 23 into which the cutters 14 and 15 extend.

The stripper blade 21 or 22 prevents soil, moss or portions of plants, which are picked up by the blades 14 and 15 from the ground 16, from adhering to the blades. The stripper 21 or 22 is journalled to pivot and is held in an end position by a bearing stud 24.

For this purpose, a spring 25 may be used.

The bearing stud 24 may also be secured to the housing of the transmission gear 13 or 18.

The blades 14 and 15 are provided with peripheral teeth 26 and 27 similar to the teeth on a blade of a circular saw. The teeth 26 and 27 may project from the cutters 14 and 15 in either a radial direction or in a direction which is inclined relative to the radial direction at an angle a thereto. If the teeth are inclined to the radial direction the teeth 26 of the cutters 14 in contact with the ground 16, when viewed in the direction of travel of the devide, are inclined rearwardly by the angle a, whilst the teeth 27 of the cutters 15 in contact with the ground 16 are inclined forwardly.

The transmission gear 13 of the apparatus comprises, as can be seen in Fig. 2, a chain wheel 28 which is located on the cutter shaft 11, a chain wheel 29 which is located on the cutter shaft 12, and a chain 30 encircling both chain wheels 28 and 29. These transmission gears may also be formed as infinitely variable transmission gears. If a chain drive used, the front (in the direction of travel) chain wheel 29 has a larger diameter than the rear chain wheel 28. The transmission ratio of the transmission gear is determined by the ratio of the diameter or radii of the wheels 29 and 28. In Fig. 5, two transmission gears are provided. Each cutter shaft 11 and 12 is provided with a large chain wheel 29 and a small chain wheel 28, the large chain wheel 29 on each shaft being connected to the small chain wheel 28 on the other shaft by a chain 30. In such a case, however, the machine can only operate if each of the transmission gears 18 is provided with free motion. It is then possible to work the soil 16 in both directions of movement of the machine, that is to say, the machine can be moved either backwardly and forwardly by means of the handle 17. This more expensive embodiment of the machine makes it possible to treat the soil more intensively.

The operation of the lawn cultivating machine of the present invention will now be described. When the machine is, for example, pushed as shown in Fig. 2, the rotations of the cutter shafts 11 and 12 are automatically adjusted according to the conditions of the soil. In the case of soil 16 which has been made uniform, if the number of cutters 14 and 15 are equal and the cutters are of equal size, the cutters 14 of the shaft 11 will roll over the surface of the soil 16 without slipping. The teeth 26 penetrate into the soil 16 but will only produce a slight cutting effect in the soil.

The cutting effect is due solely to the inclination of the teeth from the radial direction. On the other hand, the rolling movement of the cutters 15 of the shaft 12 on the soil 16 has superimposed thereon a cutting movement of the teeth 27 in the soil 16. This occurs because there is a certain amount of slip between the soil 16 and the cutters 15. These movement ratios, in which a slip occurs on the cutters 15 relative to the soil 16, but no slip occurs on the cutters 14, is due to the fact that the speeds of the cutter shafts 11 and 12 are kept within a certain transmission ratio by means of the transmission gear 13.

As a result of this transmission (in this case, reduction), ratio, the peripheral force on the cutters 15 on the slower rotating shaft 12 is greater than the peripheral force on the cutters 14 of the quicker rotating shaft 11. This can easily be accounted for by the different radii of the wheels 29 and 28.

Accordingly, the cutters 14 roll on the ground 16 without slip, whilst relative movement between the cutters 15 and the ground 16 takes place when there is contact therebetween. This movement, which causes the teeth 27 of the cutters 15 to act in the desired manner to loosen the soil, can be calculated as follows:- Let the frame 10 be moved with a speed vl over the soil 16. If R is the radius of the teeth 26 and rl is the radius of the chain wheel 28, the speed of the chain is r1 Vt R On the shaft 12, the cutters 15 are driven by the frame at the speed vl and by the chain 30 at the speed of the chain. The speed v2 of the teeth 27 on the soil 16 is therefore rl R rX V2=V,--VI . . - =V1.(1- ), R r2 r2 (since the radii R of the teeth 26 and 27 on the cutters 14 and 15 should be identical).

Since the chain wheels 28 and 29 have differing radii, the teeth 27 move relative to the soil 16 at a speed v2 which is different from vl. This speed v2 is less than the speed vl of the frame 10 because the chain, below the cutter shafts 11 and 12, that is to say, where the teeth are touching the soil is directed oppositely to the speed vl. At this speed v2, the teeth 27 execute their cutting movements in the soil 16. By suitably selecting the speeds of rotation, cutting of the soil can therefore be carried out utilising the teeth 27 of the cutters 15 on the shaft 12, whilst the teeth 26 of the cutters 14 of the shaft 11 serve almost exclusively to support the machine.

In the embodiment of the machine shown in Fig. 5, the cutters 14 on the shaft 11 are supported on the ground during movement in one direction, whilst the cutters 15 of the shaft 12 effect the cutting action. In this case, the transmission gear 18 shown on the right of the drawing is in operation whilst the transmission gear 18 on the left-hand side of the drawing, is inoperative. During the return movement of the machine in the opposite direction, the cutters 15 of the shaft 12 are supported in the soil 16, whilst the cutters 14 of the shaft 11 do the cutting work. In this case the transmission gear 18 shown on the left of the drawing is in operation, whilst the transmission gear 18 shown on the right side is inoperative. The blades of the lawn cultivating machine of the present invention effecting the cutting therefore penetrate into the soil and move therein a short distance relative to the soil.

The soil is therefore opened up and loosened. Moss and parts of plants hindering growth are therefore removed from the soil. For certain desired effects on the soil, the teeth of the cutters can also be set on the periphery of the cutters as is the case in a circular saw. The desired working width of the machine can be adjusted by joining several cutters together, at suitable clearances, on the cutter shafts. Penetration of the teeth in the soil is effected by the weight of the machine, said weight acting vertically downwardly. by means of the handle, a further force component acting vertically downwardly may be imparted to the machine. When the teeth penetrate into the soil, they act like claws therein.

If there is a lack of uniformity in the nature of the soil, the teeth of the cutters on the more slowly rotating shaft may rest in the soil, whilst the teeth of the cutters of the faster rotating shaft execute a relative movement thereto in the soil. It may also happen that the cutters of both shafts move with slip over the soil. A change in the behaviour of the cutters may also be achieved if the number of cutters on the faster rotating shaft is reduced in dependence upon the transmission ratio. In the normal case, both shafts have the same number of cutters formed thereon. Finally, the teeth on the cutters of both shafts may be made differently, thus resulting in additional types of movement of the teeth in the soil.

In Fig. 2, a skid arrangement comprising two narrow skid members 31 is shown. The ends of the skids are secured to the frame 10, one on each side thereof in the direction of movement. It is preferable to make one end of each skid, preferably the end thereof adjacent the chain wheel 29, adjustable by means of a length adjusting device 32 such as an adjustment screw. These skids 31 can limit penetration of the cutters 15 into the soil, so that the machine is easier to move.

By adjusting the level of the skids 31, the movement of the machine can therefore be varied. As shown in Fig. 4, the two skids 31 may be connected by a connecting strip 33 made integrally with the skids or merely connected therebetween. This permits both skids 31 to be vertically adjusted simultaneously by the adjustment device 32.

If, in use, moss or the residues of plants become clogged in the teeth of the cutters the stripper plates 21 and 22, which yield resiliently in the manner of pawls during movement against the incline of the teeth, clean the cutters of the material. In so doing, the strippers 21 and 22 do not come into contact with the cutters. Only the projecting material is engaged by the strippers and removed.

Since the movement of the teeth 27 is partially rotary and partially linear, moss and bulky layers in the soil 16 are not only torn open but also lifted out.

WHAT WE CLAIM IS: 1. A displaceable lawn cultivating machine comprising two parallel cutter shafts which are connected together by a transmission gear arrangement, the cutter shafts each being rotatable about a horizontal axis, each axis being at right angles to the direction of displacement of the machine, a plurality of cutters being arranged at spaced intervals from one another on each of the shafts, the cutters mounted on one shaft being off-set relative to the cutters of the other shaft, both cutter shafts, in use, rotating in the same direction, the transmission gear arrangement being such that the rate of rotation of the leading, in the direction of travel of the machine, cutter shaft is caused to be less than the speed of rotation of the rear cutter shaft.

2. A machine as claimed in claim 1 in which the cutter shafts are mounted on a common frame.

3. A machine as claimed in claim 2, in which the frame includes a yoke-shaped handle portion.

4. A machine as claimed in claim 2 or 3, in which the cutter shafts are motor-driven.

5. A machine as claimed in any preceding claim, in which the cutters are circular discs having teeth projecting radially from the circumference of each said disc.

6. A machine as claimed in any one of claims 1 to 4 in which the cutters are circular discs having teeth projecting from the circumference thereof at an angle to the radial direction.

7. A machine as claimed in claim 6, in which, in use, the teeth of the rear, in the direction of travel of the machine, cutters are inclined backwardly relative to the radial direction whilst the teeth of the forward cutters are inclined forwardly relative to the radial direction.

8. A machine as claimed in any preceding claim, in which the transmission gear is a chain drive, a chain wheel being secured to each cutter shaft, the chain wheels being enclosed by a common chain.

9. A machine as claimed in claim 8, in which the chain wheel of the rear cutter shaft in the direction of displacement of the machine has a smaller radius than the chain wheel of the front cutter shaft.

10. A machine as claimed in any preceding claim, in which the transmission gear is arranged in the central region of the cutter shafts.

11. A machine as claimed in any one of claims 1 to 9 in which two transmission gears are provided, one transmission gear connecting corresponding ends of the cutter shafts, the other gear connecting the other ends of the cutter shaft, each gear being provided with free motion.

12. A machine as claimed in any preceding claim, in which at least one of the two cutter shafts has a stripper plate associated therewith, the stripper plate being mounted on the frame and having slots formed therein into which the teeth of the cutters project.

13. A machine as claimed in claim 12, in which both cutter shafts are provided with a common stripper plate.

14. A machine as claimed in claim 13, in which the stripper plate is mounted on the frame between the cutter shafts and extends parallel to the shafts.

15. A machine as claimed in claim 14, in which the stripper plate is journalled to pivot on a shaft extending parallel to the cutter shafts and is held in an end position by a spring.

16. A machine as claimed in any preceding claim, in which skids are provided at the ends of the cutters, said skids extending in the direction of displacement of the machine, the ends of the skids being secured to the frame.

17. A machine as claimed in claim 16, in

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. two narrow skid members 31 is shown. The ends of the skids are secured to the frame 10, one on each side thereof in the direction of movement. It is preferable to make one end of each skid, preferably the end thereof adjacent the chain wheel 29, adjustable by means of a length adjusting device 32 such as an adjustment screw. These skids 31 can limit penetration of the cutters 15 into the soil, so that the machine is easier to move. By adjusting the level of the skids 31, the movement of the machine can therefore be varied. As shown in Fig. 4, the two skids 31 may be connected by a connecting strip 33 made integrally with the skids or merely connected therebetween. This permits both skids 31 to be vertically adjusted simultaneously by the adjustment device 32. If, in use, moss or the residues of plants become clogged in the teeth of the cutters the stripper plates 21 and 22, which yield resiliently in the manner of pawls during movement against the incline of the teeth, clean the cutters of the material. In so doing, the strippers 21 and 22 do not come into contact with the cutters. Only the projecting material is engaged by the strippers and removed. Since the movement of the teeth 27 is partially rotary and partially linear, moss and bulky layers in the soil 16 are not only torn open but also lifted out. WHAT WE CLAIM IS:

1. A displaceable lawn cultivating machine comprising two parallel cutter shafts which are connected together by a transmission gear arrangement, the cutter shafts each being rotatable about a horizontal axis, each axis being at right angles to the direction of displacement of the machine, a plurality of cutters being arranged at spaced intervals from one another on each of the shafts, the cutters mounted on one shaft being off-set relative to the cutters of the other shaft, both cutter shafts, in use, rotating in the same direction, the transmission gear arrangement being such that the rate of rotation of the leading, in the direction of travel of the machine, cutter shaft is caused to be less than the speed of rotation of the rear cutter shaft.

17. A machine as claimed in claim 16, in

which one end of each skid is longitudinally adjustable by means of an adjusting device.

18. A lawn cultivating machine, substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.