Adjustable Mowing and Trimming Apparatus

The invention relates generally to vegetation trimmers, and more particularly, to a combined mowing and trimming apparatus of a type that is mounted on a frame and supported on two wheels.

A variety of different types of mowing and trimming devices have been devised for meeting the requirements of particular applications. Conventional lawn maintenance, however, has required a lawn mower to cut the lawn and a lawn trimmer to trim the edges of the lawn, including areas of vegetation that border fences, buildings, etc. Flexible line vegetation trimmers are commonly used today for such trimming operations. Although the equipment for this two-part procedure is readily available, the procedure inherently involves a substantial duplication of effort since an operator must guide both types of equipment over substantially the same area, e.g., adjacent to buildings and other structures.

In response, various devices that combine mowing and trimming features in one machine have been developed. For example, such an apparatus is disclosed by Watrous in U.S. Pat. No. 2,669,826, wherein a two-wheel lawn mower is presented having a forwardly mounted cutting head that is supported on a ground engaging shoe. In Watrous the axle and housing are pivotally connected, thereby permitting the entire cutting head to swing from side to side with respect to the rear wheels and handle. This approach, however, disadvantageously leaves the handle in a position close to the structure around which vegetation trimming is to occur.

In U.S. Pat. No. 4,077,191 to Pittinger, a filament trimmer/mower is disclosed that includes a four wheel support frame. Each of the front and rear wheel-and-axle assemblies are pivotally mounted with respect to the frame. Pittinger, however, suffers from the disadvantage that the rotating head is held in a fixed position in the center of the frame between the wheels. Therefore, it is difficult to trim the vegetation growing alongside a building or other structure since the filament line would not normally extend outside the path of travel of the wheels.

Although there are numerous additional known devices in the art of combined mowing and trimming apparatus, there remains room in the art for further improvements to the known devices.

Briefly summarized, this invention comprises in one aspect a mowing and trimming apparatus which includes a frame having a front portion and a rear portion. A handle is secured to the frame at the rear portion and a trimming assembly is mounted to the front portion for rotational movement with a downwardly depending spindle. The trimming assembly has a plane of cutting substantially perpendicular to the axis of rotation of the spindle. An adjustable linkage is provided at the rear portion of the frame, with ground engaging wheels being mounted at opposite ends of the adjustable linkage. The linkage is coupled to the frame by a moveable pivot assembly. The apparatus further includes an adjustment mechanism for manually moving the moveable pivot assembly, and thereby the adjustable linkage, relative to the frame, wherein the trimming assembly remains substantially parallel to ground, and the rotatable trimming assembly, frame and handle remain fixed relative to each other notwithstanding turning of the ground engaging wheels in response to movement of the adjustable linkage.

In another aspect, the invention comprises a trimming assembly for use in a trimming apparatus having a spindle mounted to rotate about an axis of rotation. The trimming assembly includes a spindle head and a trimmer head. The spindle head is fixedly mounted to the spindle so as to rotate therewith and substantially cover an exposed portion of the spindle. The spindle head is sized such that a distal end thereof rests proximate to ground when the trimmer assembly is used in the trimming apparatus and the trimming apparatus is operational. The trimmer head, which is adjustably clamped about the spindle head so as to rotate therewith, has a plane of cutting substantially perpendicular to the axis of rotation. This plane of cutting is infinitely adjustable about a length of the spindle head such that height of the plane of cutting relative to ground is adjustable.

Various enhancements on the apparatus and assembly summarized above are also described and claimed herein.

A mowing and trimming apparatus in accordance with this invention has certain features which improve functionality, performance and durability. These features include a new trimming assembly design with improved height adjustability, spindle bearing protection and elimination of grass wrapping about the trimming assembly when the apparatus is operational. More particularly, a large range of height adjustment of the cutting plane, e.g., 1.5 inch-4.5 inch, is possible. Further, a large radius of the rotating group nearly eliminates the problem of grass wrapping, and the spindle head totally shields the spindle bearings and thus affords them protection from dirt, dust and material wrapping should it occur. As another advantage, improved exposure of the trimming head beyond the wheels is possible employing the wheel linkage and pivot adjustment assembly of the present invention. By simple actuation of an adjustment mechanism, the wheels are effectively steered between a left position, center position or right position, thus effectively placing the trimming assembly to either side of the wheels permitting convenient trimming along buildings, under fences, around trees, etc.

The subject matter which is regarded as the present invention is particularly pointed out and distinctly claimed in the concluding portion of the specification. The invention, however, both as to organization and methods of practice, together with further objects and advantages thereof, may best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a top plan view of one embodiment of a mowing and trimming apparatus in accordance with the present invention;

FIG. 2 is a side elevational view of the mowing and trimming apparatus of FIG. 1;

FIG. 3 is a perspective view of a trimmer head disc in accordance with the present invention;

FIG. 4a is a side view of the trimmer head disc of FIG. 3;

FIG. 4b is a cross-sectional view of the trimmer head disc taken along lines B--B of FIG. 4a;

FIG. 5 is a perspective view of one embodiment of a clamp plate for securing trimming line in the trimmer head disc of FIGS. 3-4b;

FIG. 6 is a perspective view of the trimmer head of the present invention with two trimming lines shown secured therein;

FIG. 7 is a perspective view of one embodiment of a spindle head in accordance with the present invention;

FIG. 7a is a side elevational view of the spindle head of FIG. 7;

FIGS. 7b & 7c are cross-sectional views of the spindle head of FIG. 7 taken along lines B--B and C--C, respectively, in FIG. 7a;

FIGS. 8a & 8b are perspective views of the trimming assembly in accordance with the present invention, each depicting a different position of the trimmer head relative to the spindle head;

FIG. 9 is a perspective view of one embodiment of a wheel adjust mechanism in accordance with the present invention; and

FIG. 10 is a perspective view of the assembly of FIG. 9 showing rotation of the wheels to a rightward orientation.

FIGS. 1 & 2 depict one embodiment of an adjustable mowing and trimming apparatus, generally denoted 10, in accordance with the present invention. Apparatus 10 includes a frame 12 having a front portion 14 and a rear portion 16. As one example, frame 12 comprises a lightweight and rigid aluminum structure sized for mounting all of the components of apparatus 10. The shape is designed so that a trimming assembly 18 is exposed at front portion 14 to facilitate unobstructed cutting of vegetation. In the example depicted, trimming assembly 18 comprises a line type trimmer, however, many of the novel concepts presented herein are applicable to blade type trimming assemblies as well.

Apparatus 10 comprises a two-wheeled structure having wheels 20 mounted at rear portion 16 on opposite sides of frame 12, but near the balance point of the apparatus. This is to minimize the weight supported by trimming assembly 18. Wheels 20 are relatively large for easy rolling and excellent maneuverability, even over rough terrain.

A wheel adjust mechanism 22 allows for significant, convenient pivoting of wheels 20 to change their orientation either to the left or to the right of frame 12, while still maintaining the wheels parallel. More particularly, mechanism 22 consists of a linkage, actuated by an operator, which steers and locks wheels 20 in a front-facing (centered) position, left oriented position or right oriented position. As can be envisioned by one of ordinary skill in the art, positioning of wheels 20 in either a left orientation or a right orientation relative to frame 12 results in trimming assembly 18 being placed to the right or left, respectively, of the parallel oriented wheels 20. In accordance with the present invention, the wheel adjust mechanism allows trimming assembly 18 to be more easily and completely exposed in the right or left position relative to the parallel oriented wheels 20 to provide improved trimming around buildings, fences, etc.

As described further below in connection with FIGS. 9 & 10, mechanism 22 is actuated by an operator lifting an arm 23, which disengages a locking pin engaged in a plate 134 at the end of the arm. Rotation of the arm about a vertical axis results in simultaneous pivoting of wheels 20 either to the left or to the right. At least a left locking position and a right locking position are provided in plate 134. As explained further below, wheel adjustment mechanism 22 can be distinguished from prior approaches of pivoting a conventional straight axle. In contrast, mechanism 22 comprises a linkage which is pivotally coupled through frame 12 to respond to a slight rotating of handle 23 either to the left or to the right. Wheels 20, which are connected at either end of the linkage respond by moving to the left orientation or the right orientation as discussed above. Because of the linkage design, this wheel movement is significantly more than that of arm 23, and more than otherwise attainable employing most any prior approach.

Connected to rear portion 16 of frame 12 is a handle assembly 24 having an upper portion 25 and a lower portion 27 coupled together pivotally 26 so that upper handle 25 can collapse to facilitate storage or transport of apparatus 10. Handle assembly 24 is fixedly secured to frame 12 and does not pivot with wheels 20. Upper handle portion 25 provides structure for an operator to propel the apparatus and provides mounting surface for a throttle 32 and an automatic shutoff 34. A conventional gasoline powered engine 30 is mounted to an upper surface of frame 12. However, those skilled in the art should note that the concepts presented herein are equally applicable to an electric powered trimming apparatus.

The crankshaft of engine 30 protrudes downward through a hole in frame 12 to an underside of the frame where a pulley attached to the crankshaft provides power to the belt drive and related components disposed on the underside of the frame. These components, which provide clutching/declutching and power transfer from the engine to the trimming assembly, are conventional. One skilled in the art is directed to any one of a number of commercially available cutting and trimming apparatus for further information on such components. The system preferably incorporates a braking feature tied to shutoff 34 to ensure that the trimming assembly does not rotate when shutoff 34 is disengaged from an operate position.

In the embodiment shown, a housing 36 partially shields engine 30, wheels 20, and an operator from any debris which may be thrown by the rotating trimming assembly 18. The housing also prevents tall cuttings from falling and becoming entangled in the engine or wheels. As depicted in FIG. 2, trimming assembly 18 comprises a trimmer head 40 and a spindle head 42. Preferred embodiments of these two components are depicted in FIGS. 3-8b, which are described below. Note that although depicted as hexagonal-shaped, any geometric shaped elongate spindle head and trimmer head center opening could be employed. For example, cylindrical, triangular or rectangular shapes could be used.

FIGS. 3, 4a & 4b depict one embodiment of trimmer head 40 in accordance with the present invention. By way of example, trimmer head 40 could comprise a flat, round plastic disc approximately one inch thick and eight inches in diameter. Trimmer head 40 has a main body 50 within which in this embodiment a hexagonal-shaped center opening 52 is defined. Opening 52 is shaped and sized so that trimmer head 40 can encircle and clamp to spindle head 42 (FIG. 2). Radial grooves 54 are cut within body 50 to allow trimmer head 40 to slip over spindle head 42 and to facilitate clamping of head 40 onto spindle head 42.

Slots 54 essentially allow for a limited pivoting of the trimmer head body to allow the part to contract and decrease the size of hexagonal hole 52 slightly to thereby clamp trimmer head 40 to spindle head 42 (FIG. 2). A threaded fastener, or other type of clamping system, applies a load sufficient to contract the trimmer head and grip the spindle head. The threaded fastener (not shown) resides within a predefined opening 55 in the body 50 of the trimmer head. Opposite ends 56 & 58 of opening 55 are sized to facilitate the insertion of the threaded fastener, e.g., a bolt and a nut, into the opening and thereby clamping of the trimmer head to the spindle head. A feature of the trimmer head and spindle head combination presented herein is the infinite adjustability of the trimmer head relative to the spindle head within a range defined by a length of the spindle head, and thus an infinite adjustability of the vegetation cut height within a range defined by the length of the spindle head. Alternatively, however, the trimmer head could be designed to adjust in graduated movements relative to the elongate spindle head.

In the embodiment presented, trimmer head 40 is designed with two line receiving channels 62 on opposite sides. The channels and the structures which define the channels are identical and symmetrical about trimmer head 40. As shown in the assembled view of FIG. 6, each segment of line 90 is disposed such that a portion thereof adjacent each end extends from the trimmer head 40. The line segments 90 are held in place by clamps 80 which are bolted 81 to the body 50 of trimmer head 40.

Channels 62 are cut into body 50 such that a partially raised portion 60 remains having an elliptical or cam shape. Each portion 60 includes an opening 61 through body 50 which aligns with an opening 82 in a clamp plate 80 (see FIG. 5), within which a bolt 81 (FIG. 6) is to reside. Each channel 62 is defined by a first wall of elliptical shaped portion 60 and a second wall of main body 50. From the periphery of trimmer head 40 it can be seen that first wall 64 essentially comprises a convex shape extending inward from the circumference of the trimmer head, while curved second wall 66 comprises a concave, or more specifically, a substantially sinusoidal shaped wall.

In operation, the trimmer head will rotate clockwise, and therefore, the trimmer head includes a tapering 72 of first wall 64 and a tapering 70 of second wall 66 away from the direction of rotation so that a line residing within channel 62 will not experience a sharp edge where the line extends from the trimmer head. This extensive contouring of the walls defining channel 62 provides an advantage over prior line trimming assemblies, which typically have a very limited opening where the line exits the trimmer apparatus. Channel 62 also includes a slightly raised portion 68 to facilitate clamping of the line segment within the trimmer head.

Referring to FIG. 5, clamp plate 80 is sized and shaped to cover a respective line receiving channel in the trimmer head. Clamp plate 80 includes cutouts 84 which are employed to define depending grips 86. When clamp plate 80 is bolted to body 50 of the trimmer head, grips 86 grab the line segment and hold the line segment in a fixed position. To replace a line segment, bolt 81 (FIG. 6) holding plate 80 (FIG. 5) to the body 50 of the trimmer head is loosened, releasing grippers 86 from engagement with the line segment, and thus allowing replacement of the line segment via its removal from channel 62 and insertion of a new line segment into the channel. Preferably, each line segment is clamped near a middle of the segment so that two roughly equal lengths of line extend outward from the trimmer head.

Trimmer head 40 also includes a groove 74 about the circumference of the trimmer head. This groove 74 is of sufficient width and depth to allow the line segments to "hide" within the groove whenever the trimmer head is inadvertently brought into physical contact with a fixed object. Should this happen, tapered portions 72 & 70 in the first wall 64 and second wall 66, respectively, prevent undue pressure from being applied to the line segments.

FIGS. 7-7c depict one embodiment of spindle head 42 in accordance with the present invention. Spindle head 42 comprises a cup-shaped structure 100 designed to encircle and rotate with an elongate spindle (not shown) driven by the drive belt and related components of the mowing and trimming apparatus. Structure 100 includes a first portion 102 which is hexagonal shaped and a second portion 104 which is cylindrical shaped. In use, second portion 104 comprises an upper portion and is adjacent to an under surface of frame 12 (FIG. 2), while the distal end 105 of the spindle head is designed to rest on the ground. Structure 100 includes a transition area 103 where the cross-sectional shape of the structure is tapered from the hex shape to the circular shape. Reinforcing ribs 106 extend radially from a center shaft 108 sized to receive the spindle (not shown) driven by the cutting and trimming apparatus. Again, those skilled in the art should recognize that the hexagonal-shaped spindle head and the corresponding hexagonal-shaped center opening in the trimmer head are provided herein by way of example only. Various other geometric shapes could be employed for the spindle head and trimmer head center opening.

As shown in FIG. 7b, a driving nut 110, for example, a star shaped washer, is secured within a corresponding opening in the distal end 105 of the spindle head. Driving nut 110 includes a hexagonal-shaped center opening which corresponds to a hexagonal-shaped spindle (not shown) to be received therein. Steps 109 are shown within shaft 108 for washers (not shown) which would encircle the spindle. Multiple drain openings 112 are provided in the distal end 105 of spindle head 42 to allow drainage of any moisture accumulated therein.

Spindle head 42, which is also constructed of plastic, has a diameter at least equal to three inches and preferably larger, e.g., 4" or 4.25". Such a large diameter, coupled with tapering 103 from the hexagonal portion 102 to the cylindrical portion 104 is responsible for significantly eliminating wrapping of cut fibrous material around the trimming assembly when the apparatus is in operation.

FIGS. 8a & 8b depict two operational embodiments of trimming assembly 18 to illustrate the range of adjustability of trimmer head 40 relative to spindle head 42. In addition to this wide range of adjustability, e.g., three inches or more, it is significant to note that the adjustability is infinite within the range provided. Thus, within this range an operator can set the cutting plane of the trimmer head to any desired height above ground. Assuming a three inch range of adjustability, then an operator might infinitely select cutting height within a range of approximately 1.5 inches to 4.5 inches as desired depending upon the type of vegetation being cut.

As best shown in these figures, spindle head 42 protects the spindle bearings (not shown) by being positioned close to the underside of frame 12 but slightly spaced therefrom to allow the spindle head to rotate relative to the frame. Spindle 122 is driven by a conventional belt drive assembly 120, which is powered by the engine of the cutting and trimming apparatus as noted above.

FIGS. 9 & 10 depict in greater detail one embodiment of a wheel adjust mechanism 22 in accordance with the present invention. As shown, mechanism 22 includes a handle 23, which passes through an opening in lower handle portion 27 sized to allow rotation of handle 23. A spring is disposed on the underside of handle portion 27 to maintain tension on handle 23 and thereby retain positioning of a locking pin 130 in one of at least three defined holes 132 in adjustable plate 134. Plate 134, which is securely connected to the lower end of handle 23 as shown, pivots about a pivot pin 136 and is spaced slightly from frame 12 to allow easy manual repositioning of locking pin 130 in a desired adjustment hole 132 through a simple raising and swinging motion applied to handle 23.

Disposed below frame 12 is a center clamp 140 fixedly secured to the other end of pivot pin 136. Clamp 140 can comprise two plates partially welded and secured together via threaded connection (not shown) to securely hold the ends of rods 142. Each rod 142 includes an area of abrasion, knurling, spline, or threading 144 to facilitate the clamping action. Advantageously, clamp 140 allows for exact parallel disposition of wheels 20 during the assembly process for the cutting and trimming apparatus. This is accomplished by loosening clamp 140 and adjusting the appropriate rod 142 as needed. Each rod 142 connects through a pivot structure 146 to an L-shaped rod or wheel arm 148. Each wheel arm is secured to a cylindrical post 150 near the bend in the arm. Each cylindrical post is loosely held within a corresponding wheel bracket 152 bolted to frame 12 such that the post 150 can rotate with pivoting of wheel arm 148 through pivot structure 146 in response to repositioning of plate 134 relative to locking pin 130.

In FIG. 9, the locking pin is shown disposed within the center adjustment hole 132 in plate 134, while in FIG. 10 the plate has been rotated so that the locking pin is now in the rightmost adjustment hole, which would cause the trimming assembly to be exposed on the left side of the parallel oriented wheels. Conversely, movement of plate 134 so that locking pin 130 is disposed in the leftmost opening (as viewed from the rear portion of frame 12) results in the trimming assembly being exposed beyond the right wheel of the apparatus. Note that multiple additional adjustment holes could also be provided in plate 134. Advantageously, the handle assembly remains fixedly disposed relative to the frame notwithstanding pivoting of the wheels and thus will be positioned away from the structure around which vegetation is being trimmed once the wheels are manually repositioned parallel to the structure.

Those skilled in the art should note from the above discussion that a mowing and trimming apparatus in accordance with this invention has certain features which improve functionality, performance and durability. These features include a new trimming assembly design with improved height adjustability, spindle bearing protection and elimination of grass wrapping about the trimming assembly when the apparatus is operational. More particularly, a large range of height adjustment of the cutting plane, e.g., 1.5 inch-4.5 inch, is possible. Further, a large radius of the rotating group nearly eliminates the problem of grass wrapping, and the spindle head totally shields the spindle bearings and thus affords them protection from dirt, dust and material wrapping should it occur. As another advantage, improved exposure of the trimming head beyond the wheels is possible employing the wheel linkage and pivot adjustment assembly of the present invention. By simple actuation of an adjustment mechanism, the wheels are effectively steered between a left position, center position or right position, thus effectively placing the trimming assembly to either side of the wheels permitting convenient trimming along buildings, under fences, around trees, etc.

While the invention has been described in detail herein in accordance with certain preferred embodiments thereof, many modifications and changes therein may be effected by those skilled in the art. For example, the trimming assembly could be fabricated to accommodate a single line segment or three or more line segments. Accordingly, it is intended by the appended claims to cover all such modifications and changes as fall within the true spirit and scope of the invention.