Harvesters – Motorized harvester – Having motor on ground-supported carrier
Reexamination Certificate
2001-06-26
2003-09-23
Kovács, Árpád Fab (Department: 3671)
Harvesters
Motorized harvester
Having motor on ground-supported carrier
C056S010800, C056S011400, C056S249000, C056S294000
Reexamination Certificate
active
06622464
ABSTRACT:
TECHNICAL FIELD
This invention relates to a walk reel mower having a reel cutting unit that “floats” relative to the reel mower frame to allow the reel cutting unit to conform to the ground contours to avoid scalping and/or scuffing of the turf being cut. In addition, this invention relates to a gearbox that integrates the traction and reel drives of the reel mower, to a self-lubricating drive shaft that transfers drive to the cutting reel, to a single control handle for operating both the traction and reel drives, to an improved mounting on the reel mower frame for supporting the grass collecting basket, to an improved pivotal mounting for the bedknife, and to an improved back plate construction for the reel cutting unit.
BACKGROUND OF THE INVENTION
Walk reel mowers are known for precision cutting of grass and the like, such as the grass found on golf greens. Such reel mowers typically have a frame which carries a reel cutting unit. A handle assembly extends upwardly and rearwardly from the frame to allow an operator who walks behind the mower to guide and operate the mower. The handle assembly includes various controls for allowing the operator to selectively engage and disengage the traction drive of the mower as well as the reel cutting unit.
Prior art walk reel mowers are known in which the reel cutting unit is carried rigidly on the frame, like that shown in U.S. Pat. No. 5,477,666 to Cotton or U.S. Pat. No. 4,481,757 to Tsuchiya. Such a cutting unit does not pitch, roll or yaw relative to the frame to adapt itself to the contours of the ground. When this mower cuts grass on an undulating surface, it is quite possible to scalp or scuff the grass. For example, the grass might be cut too closely on top of a high spot and not closely enough in a low spot. This is undesirable.
Other reel mowers, such as that shown in U.S. Pat. No. 2,972,218, disclose walk reel mowers having a “full floating cutting unit” that can move in three degrees of freedom relative to the mower frame. This is done by making the cutting unit self-supporting on its own front and rear rollers. The cutting unit is then suspended from the mower frame by a set of chains that are normally slack when the cutting unit is in engagement with the ground. The slack chains allow the cutting unit to move relative to the mower frame to better follow the contours of the ground to minimize instances of scalping and/or scuffing and to help provide a more consistent height of cut.
While the ground contour following characteristics of a reel mower are not possessed by a reel mower with a cutting unit that is rigid with the frame, the use of chains to support the cutting unit provides disadvantages of its own. When the operator pushes down on the handle assembly to raise the front end of the reel mower, the cutting unit does not immediately lift up off the ground. The chains first have to tighten before the cutting unit lifts up off the ground. Thus, when pushing down on the handle to lift the cutting unit off the ground, the operator first feels a smooth motion while the chains tighten and then feels a jerk or discontinuity when the operator suddenly has to push down harder to get the cutting unit to come up.
The jerk or discontinuity felt by the operator in the handle as the operator pushes down on the handle to raise the cutting unit is a disadvantage. Most operators prefer cutting units in which one can push down on the handle to raise the cutting unit and this can be done in a smooth motion with the cutting unit raising immediately. This is simply not possible with cutting units suspended by chains that must be tightened before the cutting unit rises.
U.S. Pat. No. 2,329,952 to Speiser discloses a walk reel mower in which a reel cutting unit is mounted on the rear of the mower frame. However, the cutting unit has a floating capability in that the cutting unit can pitch and roll relative to the frame by virtue of transverse and longitudinal pivots between the cutting unit and the mower frame. While this provides a ground contour following ability without using slack chains to support the cutting unit, pushing down on the handle assembly will not lift the cutting unit off the ground. Thus, the mower shown in the Speiser patent is much more difficult to maneuver than the reel mowers described earlier.
In addition, the cutting unit shown in the Speiser patent is not itself totally self-supporting on the ground, but relies on the traction wheels of the mower frame in conjunction with a roller on the cutting unit for proper ground engaging support. As a result, the fore-and-aft wheelbase of the mower is relatively large. This decreases how effectively the cutting unit will pitch when encountering transverse bumps or undulations in the ground, i.e. bumps or undulations that are perpendicular to the forward direction of motion. If the bump is small enough, the traction wheels may clear the bump before the cutting reel/bedknife interface reaches the high spot of the bump, thus still resulting in scalping.
Another problem with prior art walk reel mowers is the nature of the drives or transmissions used to power the traction drive and the cutting reel. Often, separate drives housed in separate gearboxes are used, one gearbox powering the traction drive and the other gearbox powering the cutting reel. The use of two gearboxes increases expense as well as requiring sufficient space on the mower frame for housing both gearboxes. In addition, the use of two gearboxes gives the mower a cluttered appearance.
Moreover, in many prior art walk reel mowers, a differential is needed to allow the left and right traction wheels, or the left and right traction drum halves, to rotate at different speeds when turning. In many prior art mowers, particularly those having a traction drum formed from traction drum halves including a left traction drum half and a right traction drum half, the differential was not carried in the speed reducing gearbox, but was instead built into the interior of the traction drum. In this location, it was difficult to keep the differential sealed and lubricated, and repair or replacement of the differential was also difficult. Moreover, any leakage of the lubricant from the differential out of the traction drum is problematic as such a lubricant can easily kill or mar the grass or turf being cut by the mower.
Some attempts are disclosed in the art to integrate the drives for the cutting reel and the traction drive into a single gearbox. One such attempt is shown in U.S. Pat. No. 1,709,791 to Jerram, in which the speed reducing gear drives used to power the traction drum and the cutting reel are housed in a common gearbox or gearcase that is built into one of the side plates of the reel mower frame. The clutches used to initiate operation of the drives for the traction drum and the cutting reel are also both housed in this common gearbox. Thus, this mower has only a single gearbox for enclosing both the traction and cutting reel drives, thus having a less cluttered appearance than mowers using multiple gearboxes.
Despite the attempt at simplification shown in the Jerram patent, various deficiencies are still present. For example, the differential for the traction drum is still housed within the interior of the traction drum. This gives rise to the lubricating and lubricant leakage problems discussed above. In addition, the overall drive and differential systems disclosed in Jerram involve the use of a large number of components, which leads again to increased cost.
In reel mowers in which the cutting unit floats to follow the contours of the ground, the drive to the cutting reel has to flex, bend and axially extend and contract to accommodate the floating motion of the cutting unit. In some mowers, such as that shown in the Speiser patent referred to above, this is accomplished using a flexible drive belt extending from one sprocket or pulley on the mower frame to another sprocket or pulley on the cutting unit. It is a problem with such a drive in keeping the belt taut as the cutting unit and mower frame move relative
Dickey Christopher C.
Goman Gerald E.
Patton Robert D.
Schnotala Donald B.
Kovács Árpád Fab
Miller James W.
The Toro Company
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