Slope mower with improved blade housing floatation

A mower vehicle includes a vehicle frame and single front and rear driven wheels. First and second blade housings are pivotally connected to each other along a longitudinal axis of the vehicle frame and are attached to first and second side frames, respectively. Each side frame is pivotally attached to the vehicle frame near the rear thereof with a hydraulically retractable and extendable cylinder assembly urging each side frame downward or upward in response to changes automatically sensed in the slope of the terrain. Ground engaging outrigger wheels attached to each side frame contact the terrain and the vehicle frame is thus maintained in a generally upright position. Two pivot point joints connect the blade housings and are located at approximately the same height as a plane containing the blades and the driven wheels include tires with a tread which is generally semi-circular in lateral cross-section with a center of the radii of the lowest part of the tread being located at approximately the average blade mowing height. Each blade housing is linked to a corresponding side frame by a mechanical linkage arm and a floatable connection that eliminate the need for rear caster wheels.

BACKGROUND OF THE INVENTION 
This invention relates to mowing vehicles in general and particularly to 
such vehicles that are responsive to changes in terrain, such that the 
vehicle body is maintained in a generally vertical orientation. 
Mowing vehicles, such as riding lawnmowers and tractors with mowing 
attachments, have long been used in mowing hillsides, particularly by 
highway maintenance personnel. Most of these vehicles do not provide means 
for adapting to changing terrain, such that when a vehicle is on a slope 
the frame tilts accordingly, which can result in the vehicle tipping over. 
Prior attempts to remedy this problem have included adapting existing 
mowing machines by providing mechanical actuation of a mower blade 
assembly to conform to the slope without significantly modifying the 
vehicle frame itself. Such modified mowers are limited in the degree of 
and types of slopes upon which they can be effectively and safely 
operated. Other devices have involved three- or four-wheeled vehicle 
frames with complex actuation of fixed deck blade housings. 
These prior art devices have proven to be only somewhat effective in mowing 
slopes and have been very expensive, prohibiting many small operators and 
municipalities from using them. 
U.S. Pat. No. 4,707,971 for a SLOPE MOWER and U.S. Pat. No. 4,869,054 for a 
SLOPE MOWER WITH SIDE FRAMES are directed to a mower designed to remain 
upright during use on a hill so the mower does not tip over and are 
incorporated herein by reference. These patents, assigned to the assignee 
of the present application, are directed to slope mowers which attempt to 
remedy the above problems. These mowers include a vehicle frame with 
single front and rear driven wheels. The vehicle frame is maintained in a 
generally upright or vertically aligned orientation by side-mounted 
hydraulic cylinder and piston rod arrangements which are actuated in 
response to a leveling system mounted on the vehicle frame. The leveling 
system senses changes in the attitude of the vehicle frame and selectively 
actuates the hydraulic cylinder arrangements to maintain the vehicle frame 
in an upright position. In U.S. Pat. No. 4,707,971, the hydraulic cylinder 
and piston rods are attached to mower blade housings with ground engaging 
caster wheels on either side of the vehicle frame, which housings are 
pivotally connected to each other along the center longitudinal axis of 
the vehicle frame. In U.S. Pat. No. 4,869,054, the hydraulic cylinder and 
piston rod arrangements are connected to a pair of side frames with ground 
engaging outrigger wheels which are hinged to the vehicle frame. A pair of 
mower housings are floatably mounted beneath the respective side frames 
and hinged to the vehicle frame and to each other. 
While the above noted mower embodiments were a major improvement over the 
prior art and have been generally satisfactory in mowing slopes up to 30 
degrees while maintaining the vehicle frame and rider in a generally 
upright position, a number of drawbacks remain. In both patents, the pair 
of mower deck housings are hinged to each other via a piano type hinge 
underneath the vehicle frame, which means that the hinge must be located 
such that the pivot point connecting the blade housings is considerably 
higher than a plane containing the mower blades. This means that, 
particularly when the mower is being operated on terrain which slopes away 
from the vehicle frame on either side, the mower blades will not be 
parallel to the surface of the terrain, resulting in uneven cutting. 
Furthermore, both patents teach the use of mower housings which are 
mounted side-by-side with synchronized blades of overlapping arcs. This 
requires a relatively complex synchronized mechanical drive linkage to 
drive the separate mower blades. Lastly, in the case of U.S. Pat. No. 
4,869,054, the side frames are hinged to the vehicle frame at a forward 
location, which arrangement requires the floating mower decks to be 
equipped with supporting and/or adjusting caster wheels at both the front 
and the rear of each mower housing. 
Thus, it is clear that a need exists for a slope mower which evenly mows 
terrain even when it slopes away from the vehicle frame on either side. 
Such a mower should have excellent traction on slopes up to 30 degrees and 
should be relatively inexpensive to own and operate. 
SUMMARY OF THE INVENTION 
A mower vehicle includes a vehicle frame with single front and rear driven 
wheels. First and second generally circular blade housings are pivotally 
connected to and laterally offset from each other along the center 
longitudinal axis of the vehicle frame. The blade housings are floatably 
attached to first and second outrigger wheel equipped side frames, 
respectively, with each side frame attached to the vehicle frame, near the 
rear thereof, at a hinge point. Each side frame has a hydraulically 
retractable and extendable cylinder assembly connected between it and the 
vehicle frame, which assemblies urge the side frames downward or upward in 
response to signals from a leveling sensor mounted on the vehicle frame. 
The leveling sensor senses changes in the slope of terrain over which the 
mower is moving and selectively controls the hydraulic cylinder assemblies 
to maintain the vehicle frame in a generally upright position through the 
side frame wheels which contact the terrain. 
Two pivot points connect the blade housings near the front and the rear 
thereof. The pivot points are located at approximately the same height as 
a plane containing the blades. The driven wheels include tires with a 
tread having a lateral external cross-section that is generally 
semi-circularly curved having an axis of curvature of the tread located 
approximately coaxially with respect to the axis of rotation of the blade 
housings and at approximately the same height as the average blade mowing 
height. The blade housings are linked to the side frames via a mechanical 
linkage arrangement which eliminates the need for rear caster wheels on 
the blade housings and which provides a strong yet floatable connection. 
OBJECTS AND ADVANTAGES OF THE INVENTION 
The principal objects of the present invention are: to provide a mower 
vehicle for mowing sloping hillsides; to provide such a vehicle which has 
means to maintain a vehicle frame and, accordingly, the operator, in a 
generally vertical or upright orientation; to provide such a vehicle which 
includes a single front and a single rear drive wheel; to provide such a 
vehicle having means for driving each of the front and rear wheels; to 
provide such a vehicle in which the front and rear wheels are equipped 
with tires with a tread which is generally semi-circular in cross-section 
and which tread has an axis of curvature located at approximately the 
height of the average mowing height; to provide such a vehicle which has 
dual blade housings offset from each other along an axis extending 
longitudinally of the vehicle frame and being pivotally connected to each 
other so as to rotate about an axis generally coaxial with the axis of the 
curvature of the tires; to provide such a vehicle which includes outrigger 
wheel equipped side frames pivotally attached to opposite sides of the 
vehicle frame near the rear thereof; to provide such a vehicle which has a 
hydraulic cylinder and piston rod arrangement connected to each of the 
side frames to bias the side frames to maintain the vehicle frame in an 
upright orientation; to provide such a vehicle in which the mower housings 
are floatably attached to the respective side frames via a mechanical 
linkage arrangement which eliminates the need for rear caster wheels, yet 
strongly supports the rear of the housings; and to provide such a vehicle 
which is relatively simple to use, economical to manufacture, and 
particularly well adapted to the proposed usage thereof. 
Other objects and advantages of this invention will become apparent from 
the following description taken in conjunction with the accompanying 
drawings wherein are set forth, by way of illustration and example, 
certain embodiments of this invention. 
The drawings constitute a part of this specification and include exemplary 
embodiments of the present invention and illustrate various objects and 
features thereof.

DETAILED DESCRIPTION OF THE INVENTION 
As required, detailed embodiments of the present invention are disclosed 
herein; however, it is to be understood that the disclosed embodiments are 
merely exemplary of the invention, which may be embodied in various forms. 
Therefore, specific structural and functional details disclosed herein are 
not to be interpreted as limiting, but merely as a basis for the claims 
and as a representative basis for teaching one skilled in the art to 
variously employ the present invention in virtually any appropriately 
detailed structure. 
Referring to the drawings in more detail, reference numeral 1 generally 
indicates a slope mower in accordance with the present invention. 
Referring to FIG. 1, this slope mower 1 includes a vehicle frame 2, an 
occupant seat 3, a front ground engaging drive wheel 4, a rear ground 
engaging drive wheel 5, and a steering wheel 11. A prime mover such as an 
internal combustion engine 12 is mounted on the vehicle frame 2 and is 
connected to at least one, and preferably both of the front and rear 
wheels 4 and 5, respectively, for propelling the slope mower 1 across the 
ground. 
The slope mower 1 is equipped with a pair of generally circular blade 
housings 13 and 14, better illustrated in FIG. 2. The blade housings 13 
and 14 are pivotally connected to each other along a center line 
longitudinal axis identified by the reference letter A of the vehicle 
frame 2 having a specific spacing above a horizontal surface as will be 
described below. As shown in FIG. 2, the right blade housing 13 is offset 
slightly forward of the left blade housing 14 along the longitudinal axis 
A. The blade housings 13 and 14 are each equipped with a single mower 
blade 15 and 16, respectively. The longitudinal offset positions of the 
blade housings 13 and 14 ensure that there is a slight overlap of the 
cutting arcs of the blades 15 and 16 along the center line of the 
longitudinal axis of the vehicle 2, as illustrated in FIG. 4. At the same 
time, this longitudinal offset ensures that the blades 15 and 16 never 
contact each other, thereby requiring no synchronization between blade 
driving units 21 and 22 as is required in many mowers having twin blades, 
thus greatly simplifying the mechanical drive mechanism for the blades 15 
and 16. Since no such synchronization is required, independent 
hydraulically actuated motors, for example, can be used for the blade 
drive mechanisms 21 and 22. 
A pair of side frames 23 and 24 are pivotally attached to the vehicle frame 
2 at a respective pair of pivot joints 25 and 26, as best illustrated in 
FIG. 8. Each of the pivot joints 25 and 26 comprises a bolt 27 inserted 
through a corresponding bore in a rear housing 31 of the vehicle frame 2, 
and through a sleeve (not shown) formed in each of the side frames 23 and 
24 and ensure that the side frames 23 and 24 are free to pivot relative to 
the vehicle frame 2 about the longitudinal axis A. A pair of hydraulically 
actuated piston and cylinder assemblies 32 and 33 are pivotally attached 
to the side frames 23 and 24, respectively, at pivot points 35 and 36. The 
other end of the hydraulic assemblies 33 and 34 is attached to the rear 
housing 31 at pivot points 41 and 42, each of which comprises a bolt and 
sleeve arrangement similar to that of pivot joints 25 and 26. The 
hydraulic piston and cylinder assemblies 32 and 33 are attached to 
hydraulic lines 43 and 44 via fittings 45 and 46, and are controlled by a 
level sensing and hydraulic control circuit as disclosed in U.S. Pat. No. 
4,869,054 earlier incorporated by reference. 
Briefly, the level sensing and hydraulic control circuit senses the slope 
of terrain over which the slope mower 1 is traveling by sensing the 
vertical orientation of the vehicle frame 2. The leveling system senses 
changes in the attitude or vertical orientation of the vehicle frame 2, 
and selectively extends or retracts one or both of the hydraulic piston 
and cylinder assemblies 32 and 33 to maintain the vehicle frame 2 in a 
generally upright position. This enables the side frames 23 and 24 and the 
blade housings 13 and 14 to maintain ground contact while the vehicle 
frame 2 (and the operator) remain vertically oriented. 
The single front wheel 4 is connected to a front section of the vehicle 
frame 2 by a steering mechanism 51 and is driven by a hydraulic motor (not 
separately illustrated) connected to the engine 12 in the manner disclosed 
in detail in U.S. Pat. No. 4,869,054. Preferably, the rear wheel 5 is also 
driven by another hydraulic motor also connected to the engine 12. 
The blade housings 13 and 14 are pivotally connected to each other at two 
pivot joints 52 and 53, as best illustrated in FIG. 7. The pivot joints 52 
and 53 are aligned along the longitudinal axis A of the vehicle frame 2 
and are located at approximately the same height above the ground as a 
plane containing the blades 15 and 16 when the mower 1 is resting on level 
and generally planar ground (see FIG. 3). This ensures that the mower 
blades 15 and 16 will evenly cut the grass on either side of the vehicle 
frame 2 regardless of the slope orientation of the terrain over which the 
mower 1 is transversing. 
Each of the pivot joints 52 and 53 comprises a circular bushing 54 
connected to the right blade housing 13 and another circular bushing 55 
connected to the left blade housing 14. The circular bushings 54 and 55 of 
the pivot joints 52 and 53 are connected together via a bolt 61 inserted 
through the center of each bushing 54 and 55 and threaded into an L-shaped 
terminus 63 of a square post 62. 
The posts 62, as are best illustrated in FIG. 3, are attached to the 
vehicle frame 2 by inserting them through corresponding square sleeves 64 
attached to the vehicle frame 2. As shown in FIG. 3, the square rods 62 
are vertically adjustable within the sleeves 64 as shown in phantom lines, 
to provide a central height adjustment for the mower housings 13 and 14. A 
plurality of vertically spaced bores 59 are provided in the rods 62 with a 
cotter pin 60 insertable therein to hold the rods 62 in a selected 
vertical position. Each of the blade housings 13 and 14 can include a rear 
mounted castering roller 67, as illustrated in FIGS. 4 and 7. FIGS. 5 and 
6 are enlarged side and end view illustrations, respectively, of the pivot 
joint 52 with FIG. 5 illustrating the blade housings 13 and 14 oriented 
horizontally with respect to each other, and FIG. 6 illustrating the blade 
housings 13 and 14 being pivoted upward with respect to each other. 
The right and left blade housings 13 and 14, respectively, are connected to 
the right and left side frames 23 and 24 via a mechanical linkage 
arrangement best illustrated in FIGS. 7 and 10-12. FIG. 7 illustrates the 
right side connection with the left side connection being a mirror image 
thereof. In particular, a short linkage arm 65 is pivotally connected to 
the right side frame 23 on one end and is pivotally connected to a 
substantially longer linkage arm 66 at the other end. Hinges 75 and 76 
respectively pivotally connecting the arm 65 to the frame 23 and the arm 
65 to the arm 66, both allowing rotation about parallel axes that are 
generally vertically aligned when the mower 1 is positioned on a 
horizontal surface, as seen in FIG. 3. The longer linkage arm 66 is, in 
turn, connected to the blade housing 13 via an adjustable rod and sleeve 
attachment best illustrated in FIG. 10. A sleeve 71, shown partially cut 
away in FIG. 10, is integrally formed in the longer linkage arm 66 with 
the interior opening of the sleeve running perpendicular to the 
longitudinal axis of the longer linkage arm 66. 
A cylindrical rod 73 is connected to the blade housing 13 via a ball and 
socket joint 74. The diameter of an inner surface 72 of the sleeve 71 is 
substantially larger than the outer diameter of the cylindrical rod 73. 
This permits the rod 73 to freely move up and down relative to the sleeve 
71 as well as to move or twist horizontally to some degree relative to the 
sleeve 71. The hinges 75 and 76 connecting the short and the longer 
linkage arms 65 and 66 to each other and to the side frame 23 must be 
extremely rigid due to the relatively long lever arm created between the 
side frame 23 and the blade housing 13. Thus, these hinges 75 and 76 are 
relatively large having large diameter pivot pins and are made of hardened 
steel or the like. 
The mechanical linkage arrangement between the side frame 23 and the blade 
housing 13 acts to eliminate the normal rear support caster wheel and 
provides an extremely resilient and improved floatation arrangement for 
the blade housing 13. For example, FIG. 7 illustrates a common situation 
where a front caster wheel 81 is striking a rock 77 while a side frame 
wheel 82 remains on level ground. The caster wheel 81 urges the blade 
housing 13 upward relative to the side frame 23, which would result 
without the currently discussed improvements in the side frame wheel 82 
being forced upward and out of contact with the ground. Due to the linkage 
arrangement illustrated in FIG. 10, however, the cylindrical rod 73 is 
forced upward through the sleeve 71 on the linkage arm 66, thus allowing 
the blade housing 13 to float relative to the side frame 23. This 
situation is illustrated in FIG. 12, where the rod 73 has traveled upward 
relative to the sleeve 71 as far as possible. 
Furthermore, the greater diameter of the inner surface 72 of the sleeve 71 
permits some lateral movement or twisting of the rod 73 relative to the 
sleeve 71, thus permitting some horizontal as well as vertical float of 
the blade housing 13, as the side frame 23 swings relative to the vehicle 
frame 2. This is particularly necessary to prevent binding in the 
connection between the side frame 23 and the blade housing 13 as the side 
frame 23 swings due to different radiuses of rotation for these two parts 
at the location of connection therebetween and because both are connected 
at laterally and vertically spaced locations to the main frame 2. FIG. 11 
illustrates the blade housing 13 returning to its normal horizontal 
position due to the force of gravity after the caster wheel 81 has left 
the rock 77 of FIG. 7. Furthermore, the hinges 75 and 76 allow horizontal 
stability of the blade housing 13 even while the side frame 23 is moved 
down or up by the hydraulic assembly 32 in response to the leveling 
system. It is noted that the support frame 23 is positioned to the rear of 
and spaced from the blade housing 13 and specifically the support frame 23 
is connected to the rear of the main frame 2. 
Cutting height adjustment of the slope mower 1 is accomplished by adjusting 
six suspension joints for the blade housings 13 and 4. Each of the front 
caster wheels 81 has an upright rod 85 connected thereto which engages a 
sleeve 83 attached to the blade housings 13 and 14. A plurality of 
adjustment bushings 84 are movable between a position below the sleeve 83 
and a position above the sleeve 83, thus raising or lowering the blade 
housing 13 relative to the caster wheel 81. A cotter pin 86 inserted 
through a bore 87 near the top of the rod 85 secures the bushings 84 and 
the sleeve 83 in a selected position. 
Adjustment of the mechanical linkage suspension points is best illustrated 
in FIG. 10. Again, a cotter pin 88 is inserted through one of a series of 
bores 91 through the cylindrical rod 73, thus selecting the height of the 
mower deck 13 by controlling the length of the rod 73 which is allowed to 
extend below the sleeve 71. As stated earlier, a similar arrangement 
allows the center square support rods 62 to be adjusted relative to the 
sleeves 64 attached to the vehicle frame 2, as best illustrated in FIG. 3. 
This height adjustment at all six different suspension locations of the 
pair of blade housings 13 and 14 permits extremely precise mower blade 
height adjustment for an even mowing job. 
FIGS. 1, 8 and 9 illustrate the shape of the front and rear tires 91 
attached to the front and rear wheels 4 and 5 of the vehicle frame 2. The 
tires 91, as best illustrated in FIG. 8, are turf traction tires having a 
tread 93 that is generally semi-circular when viewed in lateral 
cross-section with the point 92 indicating the center associated with the 
radius of the tread 93 located at approximately the height of the average 
blade mowing height and having the longitudinal axis A passing 
therethrough. The tread 93 of the tires 91 gives increased traction to the 
vehicle frame 2 by placing a greater portion of the tire tread 93 in 
contact with the ground when the terrain is sloped, as illustrated in FIG. 
9. FIG. 9 also illustrates the center point 92 of the circular tire 91 at 
approximately the height of the average blade mowing height. This is an 
important improvement that maintains the central sides of the mower 
housings 13 and 14 at a proper cutting height on slopes. For example, if 
the blades 15 and 16 are generally set to cut at between two and four 
inches, the center point 92 would be placed at three inches above the 
ground. The combination of this placement of the center point 92 and the 
placement of the blade housing hinges 52 and 53 so as to pivot about the 
longitudinal axis A and so as to be at approximately the same height as 
the plane containing the mower blades 15 and 16, ensures that, as the 
vehicle chassis 2 is rotated relative to the blade housings 13 and 14, the 
blades 15 and 16 follow the contour of the terrain as closely as possible. 
This is due to the fact that the two center points 92 stay at the same 
height above the ground even as the wheels 4 and 5 pivot from side-to-side 
on hilly or uneven ground and with the axes of rotation of the blade 
housing pivot joints 52 and 53 in approximate alignment, as illustrated in 
FIGS. 8 and 9, thus providing a stable center axis for the floating blade 
housings 13 and 14. This ensures a substantially consistent mowing height 
as the housings 13 and 14 pivot relative to each other on an uneven slope. 
It is to be understood that while certain forms of the present invention 
have been illustrated and described herein, it is not to be limited to the 
specific forms or arrangement of parts described and shown.