Abstract:
A hovermower is comprises a motor for driving a cutter about a substantially vertical axis beneath a protective deck, a mechanism generating a cushion of pressurized air beneath the deck, and a handle for maneuvering the deck over the ground, the deck being pivotable relative to the handle about a first substantially horizontal axis, characterised in that the deck is further pivotable relative to the handle about a second horizontal axis transverse to the first axis.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a rotary lawn mower, particularly one of the type that floats on a cushion of air and which is generally known as a hovermower. 
     A conventional hovermower works most effectively on flat ground. When used on a rough or undulating terrain, there is a significant loss in performance and the mower becomes difficult to maneuver as the user attempts to follow the contours of the ground. 
     A walk-behind rotary lawn mower generally includes a motor for driving a cutter about a substantially vertical axis beneath a protective deck, and a handle for maneuvering the deck over the ground. The motor, deck and cutter have a fixed relationship but, in a hovermower, the handle is generally free to pivot backwards and forwards relative to the deck about a transverse horizontal axis. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a hovermower comprising a motor for driving a cutter about a substantially vertical axis beneath a protective deck, means for generating a cushion of pressurised air beneath the deck, and a handle for maneuvering the deck over the ground, the deck being pivotable relative to the handle about a first substantially horizontal axis characterised in that the deck is further pivotable relative to the handle about a second horizontal axis transverse to the first axis. 
     Preferably, the deck is freely pivotable about both the first and second axes so that it is able to follow the contours of the ground over which the deck is passing without the user having to apply any tilting effort through the handle. However, in some cases the pivotal movement may be achieved against a resilient bias. Moreover, the handle can be pivoted by the user from side to side as well as backwards and forwards without tilting the deck, and this significantly improves the maneuverability of the mower, particularly when mowing around obstacles such as trees and bushes. With a conventional hovermower, sideways movement is more awkward and generally involves straining the user&#39;s back muscles. 
     In one embodiment the handle is pivoted on a member bounding the motor, and the bounding member is pivotally connected to the deck. The bounding member preferably comprises a cover shrouding the motor. In this embodiment the handle preferably comprises a forked or pram handle having two fores pivotally connected to first diametrically opposed sections of the member bounding the motor for pivotal movement about the first horizontal axis, and the deck is pivotally connected to second diametrically opposed sections of the bounding member for pivotal movement about the second horizontal axis, the first and second diametrically opposed sections being mutually perpendicular to one another. 
     In a second embodiment the handle is pivoted on the deck for rotation back and forth about the first horizontal axis, and the handle includes a resilient link so arranged that the portion of the handle grasped by the user can pivot from side to side relative to the portion of the handle pivoted on the deck. 
     In a third embodiment the handle is connected to the deck through a ball joint, the handle being constrained by a first guide member for pivotal movement about one of the two transverse axes, and the guide member being constrained for pivotal movement about the other of the two axes. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     An example of each of these embodiments of the invention will now be described with reference to the accompanying drawings in which: 
     FIG. 1 is a view of a first hovermower embodying the invention with its handle in an operating position; 
     FIG. 2 is a similar view of the mower of FIG. 1 with its handle in a parked position, 
     FIG. 3 is a similar view of the mower of FIG. 1 with the cover tilted relative to the deck. 
     FIG. 4 is an exploded view showing the main components of the mower. 
     FIG. 5 is a sectional view illustrating the pivotal mounting of the cover on the deck; 
     FIG. 6 is a sectional view illustrating the pivotal mounting of the handle on the motor housing; 
     FIG. 7 is a detail illustrating a mechanism for preventing sideways movement of the handle when the handle is retained in an upright parked position; 
     FIG. 8 is a schematic front view of a second hovermower embodying the invention; 
     FIG. 9 is a schematic side view of a third hovermower embodying the invention; 
     FIG. 10 is a schematic front view of the mower shown in FIG. 9; and 
     FIG. 11 is a schematic plan view of the mower shown in FIG.  9 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring first to FIGS. 1-7, the illustrated hovermower has a motor  10  driving a fan  11  and a cutter blade  12  about a vertical axis. The fan and the blade rotate beneath a protective deck  14  and the motor is enclosed within an air filter housing  15  having a top part  15   a  and a bottom part  15   b  (FIG.  4 ). 
     The motor housing  15  is shrouded by a cover  16 , and the deck  14  is pivotally connected to the cover at front and rear pivots  30   a ,  30   b  so that the deck is free to pivot relative to the cover about a first horizontal axis. A pram handle  17  is also pivotally connected to the cover  16  at opposed pivots  31   a ,  31   b  so that the handle is free to pivot backwards and forwards about a second horizontal axis perpendicular to the first axis when manoeuvring the deck  14  over the ground. 
     The pivotal connection of the handle  17  to the cover  16  allows the deck  14  to pivot backwards and forwards relative to the handle while allowing the user to maintain the handle at a comfortable height when moving in a forward or backward direction. At the same time, the pivotal connection of the deck  14  to the cover  16  allows the deck to tilt from side to side relative to the handle so that the combination of the pivotal connection between the handle and the cover and the pivotal connection between the cover and deck about mutually perpendicular axe ensures that the deck is free to follow the contours of the ground without the user having to apply any effort through the handle. This not only improves the performance of the mower but is less tiring to use, particularly over rough or undulating terrain. If the deck meets a gradient when moved forward, backward or to one side, it will automatically tilt so that it lies generally parallel to the gradient without the user having to tilt the handle. This applies regardless of whether the gradient is upwards or downwards. The deck therefore appears to the user as if it is floating over the ground. 
     Referring particularly to FIGS. 4-6, the pivotal connections between the handle  17  and the cover  16 , and between the cover  16  and the deck  14 , are illustrated. The deck  14  includes a pair of mountings  30   a ,  30   b  which are inserted between inner and outer walls  31   a ,  31   b  of the cover  16  and which each include openings for receiving respective pivot pins  32  when aligned with corresponding openings  33  in the inner and outer walls of the cover. The deck  14  is therefore free to pivot relative to the cover  16  about a horizontal axis passing through the mountings  30   a ,  30   b  and therefore extending from the front to the back of the mower. 
     At the same time, the cover  16  includes a pair of openings  34   a ,  34   b  located toward the rear which receive the respective forks of the pram handle  17 , the end portions  36  of the forks being flattened and including circular openings for receiving respective pivot pins  32  when aligned with corresponding openings in a double-walled flange portion  35  of the cover  16 . 
     The cover  16  is therefore free to pivot about a horizontal axis passing through the flattened end portions  36  of the forked handle  17 , and any pivotal movement of the cover  16  will be transmitted to the deck  14  through the connections between the cover and the deck. 
     The handle  17  can be moved from its inclined operating position (FIG. 1) into an upright parked position as shown in FIG. 2. A detent arrangement may retain the handle in its parked position in a known manner. In addition, a mechanism is provided to prevent the cover from pivoting sideways relative to the deck  14  when the handle is retained in the parked position. This mechanism is illustrated in FIGS. 4 and 7 and consists of a pair of projections  37   a ,  37   b  on the deck  14  which engage the bottom surface  38  of the flattened end portions  36  of the handle  17  when the handle is in its upright position but which lie clear of the bottom surface  38  when the handle is in its operating position. 
     Thus, in the drawing of FIG. 7 further downward movement of the flattened end portion  36  of the handle which would occur if the cover  16  was tilted about the horizontal axis passing through the mountings  30   a ,  30   b  (FIG. 4) is prevented by the projection  37   a  engaging the surface  38 . 
     As illustrated, the pivot connections  30  and  31  preferably allow free pivotal movement but movement of the deck  14  out of the horizontal plane could be achieved against a spring bias using any convenient form of spring such as a coil, tension, compression, leaf, torsion, or sprung wire. Alternatively, the same effect can be achieved by the use of an offset pivot arrangement where the respective pivots  30   a ,  30   b  are offset in a vertical plane. 
     Referring next to FIG. 8, the schematically illustrated hovermower is similar to that shown in FIGS. 1-7 but without the pivot connections  30   a ,  30   b  between the cover  16  and the deck  14 . Like parts are denoted with like reference numerals. 
     In this example the hovermower includes a pram handle  17  having a lower section  17   a  pivotally mounted on a pair of brackets  40  secured to the deck  14 , and an upper section  17   b  connected to the lower section by a resilient link  41 . 
     As in the first example, the pivotal connection of the handle  17  at the brackets  40  allows the deck to tilt forwards and backwards about a horizontal axis relative to the handle  17  while the user is able to maintain the handle at a comfortable height. However, the tilting of the deck from side to side about a horizontal axis extending from front to rear of the mower is now achieved by the lower portion of the handle tilting relative to the upper portion of the handle through the resilient link  41 . This is again achieved without the user having to apply any tilting effort through the handle. 
     The resilient link  41  will also act as a shock absorber by permitting limited movement of the upper section  17   b  of the handle toward and away from the lower section  17   a.    
     Referring next to FIGS. 9-11, the schematically illustrated hovermower is similar to that in the previous examples and like components are again denoted with like reference numerals. 
     In this example the pivot connections  30  and  31  are omitted and the handle  17  consists of a single steering arm which forms a ball joint with the cover  16 . The steering arm thus terminates in a curved plate  51  which runs in a guide slot  52  formed by overhanging projections  53  of a curved guide plate  54  which in turn has projecting pegs  55  running in respective guide slots  56  formed in the curved wall of the cover  16 . The pegs and guide slots are so arranged that the deck  14  is able to tilt about two mutually perpendicular horizontal axes relative to the handle  17 , the sideways tilting movement being shown in FIG.  9  and the fore and aft tilting movement being shown in FIG.  10 . 
     Although in the first described embodiment the first horizontal axis between the pivots  31   a  and  31   b  intersects the second horizontal axis at a point mid-way between the pivots  30   a  and  30   b , it will be appreciated that in other embodiments the two axes may be in different horizontal planes and one axis may intersect the other at a point that does not lie between the two pivot points defining the other axis.