1. Field of the Invention
This invention relates to methods and machines for creating artistic patterns in lawns, and also to machines for cutting lawns.
2. Description of Prior Art
Various types of grass cutting technologies are known, including a horizontal rotating blade known as a rotary mower, a horizontal helical shearing cutter known as a reel-type mower, and rotating flails of several types, such as a flexible cord extending radially from a rotating hub and stiffened by centrifugal force. Flails also include rigid or semi-rigid blades or cords that are pivotally attached to a rotating hub, and are urged into radial orientation by centrifugal force. An advantage of flails is that they can withstand contact with solid objects such as walls, landscaping borders, tree roots, etc., with less damage to the solid object and less damage to the cutter than with rigid blades.
Grass playing fields for professional sports are often prepared by lawn keepers to show geometric patterns such as circles, lines, letters, and portraits. A common way of doing this is to mow the grass using a reel-type mower with a roller behind the cutter that bends the grass leaves in the direction of travel. The mower is used in different directions to make the grass appear in patterns of darker and lighter stripes. Where the grass leans toward an observer, it appears darker. Where it leans away from an observer, it appears lighter. Rotary mowers can also be used if they have a following roller. However, reel-type mowers produce a cleaner and more uniform cut that can be more uniformly bent by a roller.
Another pattern-making method is to mow a field uniformly with a reel or rotary type mower, then make a pattern in the grass using rollers only. For example, in the pattern-making stage, a mower with rollers can be used with the cutter turned off, so only the rollers are used. This method makes it easier to cut the lawn evenly without missing spots, then concentrate on the route for making the pattern.
An objective of this invention is to provide a lawn sculpting machine that efficiently cuts channels of shorter grass in a previously mowed lawn to produce artistic patterns on the lawn.
This objective is met with a grass cutter using flail-type centrifugally stiffened blades pivotally mounted on a cutter hub on a motor shaft. The cutter and a motor assembly are mounted on wheels. Preferably the cutter rotation axis is parallel to the direction of travel. This efficiently sculpts a concave channel in grass as the machine is rolled across a lawn. A laterally extending guide tube may be attached to the machine to visually guide a user in cutting a channel parallel to a previously cut channel.
20. Motor case
22. Motor or engine
24. Cooling air
26. Cooling air inlet filter
28. Motor shaft
29. Shaft rotation
30. Cutter hub
30A. First cutter hub in a multiple cutter hub array
30B. Second cutter hub in a multiple cutter hub array
30C. Third cutter hub in a multiple cutter hub array
30D. Fourth cutter hub in a multiple cutter hub array
32. Cutter blade or flail
32A. Cutter blade on first cutter hub in multiple cutter hub array
32B. Cutter blade on second cutter hub in multiple cutter hub array
32C. Cutter blade on third cutter hub in multiple cutter hub array
32D. Cutter blade on fourth cutter hub in multiple cutter hub array
34. Cutter flail pivot pin
36. Air impeller
38. Cutter safety shroud
40. Cutter discharge chute
42. Wheel
44. Axle
46. Cutting guide tube
48. Cutting guide pivot
50. Cutting guide extension adjustment
52. Handle tube
54. Handle bar
60. Grass
62. Groove cut into grass
The configuration of
The distal ends of the rotating flails 32 describe a cutting circle. A safety shroud 38 surrounds at least a part of cutting circle, including radially around it except below it. A discharge chute 40 extends from the shroud to discharge grass cuttings. An air impeller 36 is attached to the cutter hub 30 to provide air flow 24 for grass discharge. The impeller may also provide air flow to cool the motor. For example an electric motor 22 may be arranged as shown in
A handle tube 52 may be provided with a proximal end attached to the motor case or chassis. The handle tube has a distal end with a handle bar 54 for pushing the sculpting machine in a direction of travel. At least two transport wheels 42 are mounted on respective parallel axles 44 attached to the motor case or chassis. Preferably two transport wheels 42 are mounted on opposite ends of a single axle 44 as shown. In the claims, the term “substantially parallel axles” includes the situation in which a single axle is used for two wheels. A two-wheel configuration as shown allows the user to make cutting depth adjustments by changing the vertical angle at which the handle tube 52 is held. The handle tube 52 preferably has length adjustability (not shown), using known means such as bolts or spring-loaded pins in selectable holes.
Artistic patterns often require parallel lines, as in for example concentric circles and checkerboard patterns. A laterally extendable guide tube 46 may be provided to visually guide the user in cutting parallel lines. The guide tube has a length adjustment 50. For example the guide tube may comprise telescoping nested tubes locked with a threaded collet sleeve 50 or other known means. The user sets the length of the guide tube to a desired distance between parallel cuts. Then the user pushes the machine beside a previous cut while visually maintaining the distal end of the guide tube over the previous cut. A rubber band may be provided on the proximal segment of the guide tube to provide a distance indication when it is shorter than the proximal segment of the tube. The guide tube is mounted by a pivot attachment 48 on a distal end of a wheel axle or on another stationary part. It has a pivot stop that holds the guide tube approximately horizontal, but allows it to be folded upward or against the handle tube when not in use.
Although the present invention has been described herein with respect to preferred embodiments, it will be understood that the foregoing description is intended to be illustrative, not restrictive. Modifications of the present invention will occur to those skilled in the art. All such modifications that fall within the scope of the appended claims are intended to be within the scope and spirit of the present invention.