Patent Description:
A rotary mower system includes a mower disc that rotates about a central axis of rotation. The central axis of rotation is arranged substantially vertical, such that the mower disc rotates on a substantially horizontal plane. The mower disc extends radially outward from the central axis of rotation to an outer peripheral edge of the mower disc. A knife is attached near the outer peripheral edge of the mower disc. Often, a pair of knives are attached opposite each other across the central axis of rotation. Rotation of the mower disc about the central axis of rotation imparts a centrifugal force to the knife, which biases the knife into a cutting position for cutting vegetation. When in the cutting position, the knife extends radially outward relative to the central axis of rotation. The knife may be attached to the mower disc in a manner that enables the knife to rotate relative to the mower disc in order to limit and/or reduce damage to the knife and/or the mower system in response to the knife striking a hard object, such as a rock or a stump. The knife is a wear item, which may need to be replaced.

Rotary mower systems are e.g. known from <CIT>, <CIT> and <CIT>.

A rotary mower system is provided. The rotary mower system includes a mower disc. The mower disc includes a body that is rotatable about a central axis of rotation. The body includes an upper surface and a lower surface positioned beneath and opposite the upper surface. The body extends radially outward from the central axis of rotation and defines an elongated slot passing therethrough. The elongated slot passes between the upper surface and the lower surface of the body. A retention block is attached to and rotatable with the body. The retention block includes a recessed surface positioned against the upper surface of the body. The recessed surface of the retention block cooperates with the upper surface of the body to define a pocket therebetween. The pocket includes a radially outer portion and a radially inner portion. The retention block includes a cover portion that at least partially covers the elongated slot over the radially outer portion of the pocket. A pin includes a shank portion passing through the elongated slot. The shank portion of the pin is moveable within the elongated slot along a radially extending path relative to the central axis of rotation, between the radially outer portion of the pocket and the radially inner portion of the pocket. The pin includes a head portion that is attached to the shank portion. The head portion is positioned within the pocket between the retention block and the body of the mower disc. When the head portion of the pin is disposed in the radially outer portion of the pocket, the cover portion of the retention block at least partially covers the head portion of the pin to prevent withdrawal of the pin from the elongated slot. When the pin is disposed in the radially inner portion of the pocket, the cover portion of the retention block does not cover the head portion of the pin, thereby allowing vertical movement of the pin and withdrawal of the pin from the elongated slot. A knife is positioned adjacent the lower surface of the body. The knife is coupled to the shank portion of the pin.

In one aspect of the disclosure, the elongated slot includes a long dimension and a short dimension. The long dimension of the elongated slot extends radially outward from the central axis of rotation and defines a first distance. The short dimension of the elongated slot extends perpendicular to the long dimension and generally orthogonal to the central axis of rotation. The short dimension of the elongated slot defines a second distance. The first distance of the long dimension of the elongated slot is greater than the second distance of the short dimension of the elongated slot.

In one aspect of the disclosure, the shank portion of the pin defines a diameter. The diameter of the shank portion of the pin is less than the second distance of the short dimension of the elongated slot. As such, the shank portion of the pin may pass freely through the elongated slot.

The head portion of the pin defines a head width. The head width is the maximum width of the head portion measured parallel to the short dimension of the elongated slot. The head width is greater than the second distance of the short dimension. As such, the head portion of the pin may not pass through the elongated slot, with a lower surface of the head portion resting on the upper surface of the body of the mower disc.

In one aspect of the disclosure, the retention block includes an access opening. The access opening extends from a top surface of the retention block to the recessed surface to provide vertical access to the pocket from above. The access opening includes an opening width that is greater than the head width of the head portion of the pin. As such, the head portion of the pin may pass through the access opening from above and into the pocket defined by the retention block.

In one aspect of the disclosure, the rotary mower system may include an upper plate that is moveably attached to the body. The upper plate is configured for pivotable movement between an engaged position and a disengaged position. When the upper plate is disposed in the engaged position, the upper plate covers the access opening from above. When the upper plate is disposed in the disengaged position, the upper plate exposes the access opening from above, thereby providing access to the access opening from above the mower disc.

In one implementation of the disclosure, the upper plate may include a protrusion. The protrusion may be shaped to nest within and penetrate into the access opening of the retention block when the upper plate is disposed in the engaged position. As such, a portion of the protrusion may extend into the radial inner portion of the pocket. The protrusion prevents movement of the head portion of the pin into the radially inner portion of the pocket, thereby retaining the head portion of the pin in the radially outer portion of the pocket. With the head portion of the pin secured in the radially outer portion of the pocket, with the retention block covering the head portion of the pin, the pin is prevented from dislodging from the elongated slot.

In one implementation of the disclosure, the upper plate may include a resilient spring steel plate. The resilient spring steel plate may be configured to return to an initial shape after bending. As such, the upper plate may be temporarily bent upward to remove the protrusion from the access opening, whereby the upper plate may be moved away from the retention block and into the disengaged position. The resiliency of the spring steel plate returns the upper plate to its initial shape. Additionally, the resiliency of the spring steel plate biases the upper plate downward onto the retention block to maintain the protrusion within the access opening.

In one implementation of the disclosure, the upper plate includes a planar portion having a plate thickness. A bushing is mounted to the planar portion of the upper plate. The bushing has a bushing thickness that is greater than the plate thickness such that the bushing stands proud of the planar portion. A first fastener passes through the planar portion and the bushing, and secures the upper plate relative to the body. Because the bushing stands proud of the planar portion of the upper plate, the first fastener does not bind the upper plate against the mower disc, thereby allowing the upper plate to rotate about an axis defined by the first fastener, relative to the mower disc. This enables movement of the upper plate between the engaged position and the disengaged position.

In one aspect of the disclosure, the pocket defines a pocket width. The pocket width is measured parallel to the short dimension of the elongated slot. The pocket width is greater than the head width of the head portion of the pin. As such, the head portion of the pin may move freely within the pocket along the radially extending path of the pin.

In one aspect of the disclosure, the rotary mower system may further include a lower support. The lower support is fixedly attached to the body of the mower disc adjacent and below the lower surface of the body. The lower support includes a knife support portion. The knife support portion is spaced vertically below the lower surface of the body. The knife is positioned between the body and the knife support portion of the lower support. The knife support portion may define a support recess. The support recess may extend completely through the lower support to define a through bore, or may include a blind bore that does not extend completely through the lower support. A distal end of the shank portion of the pin, opposite the head portion of the pin, may be disposed within the support recess when the pin is disposed in the radially outer portion of the pocket.

In one aspect of the disclosure, the knife includes a bore extending therethrough. The shank portion of the pin passes through the bore of the knife to secure the knife relative to the body. The distal end of the shank portion extends into the support recess of the lower support.

In one implementation, the support recess includes an elongated shape having a long dimension and a short dimension. The long dimension of the support recess extends radially outward from the central axis of rotation. The short dimension of the support recess extends perpendicular to the long dimension of the support recess, and is generally orthogonal to the central axis of rotation. The long dimension of the support recess is greater than the short dimension of the support recess. In one implementation, the long dimension of the support recess is less than the long dimension of the elongated slot. In one implementation of the disclosure, the shank portion of the pin defines a diameter that is less than the short dimension of the support recess. In another implementation of the disclosure, the short dimension of the elongated slot is approximately equal to the short dimension of the support recess.

A method of attaching a knife to a mower disc of a rotary mower system is also provided. The mower disc includes a body rotatable about a central axis of rotation. The method includes providing the mower disc with an elongated slot and a retention block. The elongated slot passes through the body of the mower disc between an upper surface and a lower surface of the body. The retention block is attached to and rotatable with the body. The retention block includes a recessed surface positioned against the upper surface of the body of the mower disc. The recessed surface cooperates with the upper surface of the body to define a pocket therebetween. The pocket includes a radially outer portion relative to the central axis of rotation that at least partially covers the elongated slot, and a radially inner portion relative to the central axis of rotation that does not cover the elongated slot. A knife is positioned between the lower surface of the body and a lower support. The lower support is attached to the body, such that a bore of the knife is aligned with the elongated slot and a support recess of the lower support. A pin is inserted through an access opening of the retention block and through the elongated slot until a head portion of the pin rests against the upper surface of the body, whereby a shank portion of the pin passes through the bore of the knife and at least partially penetrates into the support recess of the lower support. The pin is moved relative to the body in a direction radially outward and away from the central axis of rotation, so that the head portion of the pin is disposed in the radially outer portion of the pocket such that the retention block at least partially covers the head portion of the pin to prevent withdrawal of the pin from the elongated slot. Movement of the pin along the elongated slot in a direction radially inward and toward the central axis of rotation is blocked after the head portion is disposed in the radially outer portion of the pocket, to secure the pin relative to the body.

In one aspect of the method described herein, the shank portion of the pin is aligned relative to the retention block, such that the shank portion forms an insertion angle relative to the central axis of rotation and is positioned to pass through the access opening of the retention block and through the radially inner portion of the pocket at the insertion angle. Prior to moving the pin into the radially outer portion of the pocket, and once the pin is positioned with the shank portion passing through the elongated slot of the body, the bore of the knife, and the support recess of the lower support, the pin is rotated from the insertion angle to be substantially parallel the central axis of rotation.

In one aspect of the method described herein, an upper plate of the rotary mower system may be bent vertically upward and away from the mower disc to dislodge a protrusion of the upper plate from interlocking engagement with the access opening of the retention block disposed on the mower disc. When the protrusion is dislodged from the access opening, the upper plate may be moved relative to the mower disc to provide access to the access opening from above.

In one implementation of the method described herein, the step of blocking movement of the pin along the elongated slot in the direction radially inward and toward the central axis of rotation includes moving the upper plate relative to the mower disc so that the protrusion is aligned with the access opening. A spring force inherent in the upper plate biases the protrusion into interlocking engagement with the access opening and blocks movement of the pin toward the central axis of rotation.

Accordingly, rotary mower system and method described herein provides a simple and easy system/process to installing/removing the knife. During operation, centrifugal forces generated by rotation of the mower disc about the central axis of rotation move the pin radially outward into the radially outer portion of the pocket, which blocks vertical movement of the pin to prevent the pin from being dislodged from the elongated slot. When the upper plate is disposed in the engaged position, the protrusion in the upper plate blocks radial movement of the pin to maintain in the radially outer portion of the pocket. The knife may be changed by simply bending the upper plate upward so that the protrusion is dislodged form the access opening, and then rotating the upper plate into the disengaged position. The knife and the pin may then be moved radially inward so that the pin aligns with the access opening and then moved vertically upward out of the elongated slog to disengage the knife. In order to install the knife, the upper plate may be bent upward and rotated into the disengaged position. The bore of the knife is aligned with the elongated slot, and the pin inserted through the access opening at the insertion angle, and thereafter rotated into the vertical position. Once rotated into the vertical position, the pin may be moved radially outward relative to the central axis of rotation and the upper plate moved back into the engaged position to secure the knife relative to the mower disc.

Referring to the Figures, wherein like numerals indicate like parts throughout the several views, an example implementation of a rotary mower system is generally shown at <NUM> in <FIG>. The example implementation of the rotary mower system <NUM> shown in <FIG> is configured to include a cutter bar <NUM> having a plurality of cutting modules <NUM> typically used for cutting hay and/or other forage materials. However, it should be appreciated that the rotary mower system <NUM> may be configured differently than the example implementation shown in <FIG>. For example, the rotary mower system <NUM> may alternatively be configured with only a single cutting module <NUM> for cutting brush material. It should be appreciated that the teachings of this disclosure may be applied to many different configurations of the rotary mower system <NUM>, other than those mentioned herein.

Referring to <FIG>, each of the cutting modules <NUM> of the rotary mower system <NUM> includes a mower disc <NUM> having at least one knife <NUM> attached thereto. In the example implementation, each mower disc <NUM> includes a pair of opposing knives <NUM> attached to their respective mower disc <NUM>. However, it should be appreciated that the number of knives <NUM> of each cutting module <NUM> may vary, and that each cutting module <NUM> may be configured with any number of knives <NUM>, i.e., one or more knives <NUM> per cutting module <NUM>. A single cutting module <NUM> is described in detail below.

Referring to <FIG>, the mower disc <NUM> includes a body <NUM>. The body <NUM> is rotatable about a central axis of rotation <NUM>. The rotary mower system <NUM> includes a drive system (not shown) operable to rotate the body <NUM> about the central axis of rotation <NUM> for cutting/mowing crop material and/or vegetation. The specific features and operation of the drive system are not pertinent to the teachings of this disclosure, are understood by those skilled in the art, and are therefore not described in greater detail herein.

The body <NUM> extends radially outward from the central axis of rotation <NUM> to an outer peripheral edge <NUM>, and may generally include a plate structure. The body <NUM> includes a central portion <NUM> disposed near the central axis of rotation <NUM>, and a flange portion <NUM> disposed proximate the outer peripheral edge <NUM>. In one implementation, the flange portion <NUM> is substantially perpendicular to the central axis of rotation <NUM>. The body <NUM> includes an upper surface <NUM> and a lower surface <NUM> positioned beneath and opposite the upper surface <NUM>. As used herein, the terms upper, top, above, lower, beneath, bottom refer to a relative position along the central axis of rotation <NUM> when the rotary mower system <NUM> is positioned for operation. When positioned for operation, the lower surface <NUM> of the body <NUM> is positioned to face a ground surface, with the upper surface <NUM> of the body <NUM> generally facing skyward. As such, the upper surface <NUM> of the body <NUM> is disposed vertically above the lower surface <NUM> of the body <NUM> during operation.

The body <NUM> defines an elongated slot <NUM>. The elongated slot <NUM> passes through the body <NUM> in a direction parallel with the central axis of rotation <NUM>, between the upper surface <NUM> and the lower surface <NUM> of the body <NUM>. As best shown in <FIG> and <FIG>, the elongated slot <NUM> includes a long dimension <NUM> and a short dimension <NUM>. The long dimension <NUM> of the elongated slot <NUM> extends radially relative to the central axis of rotation <NUM> and is generally perpendicular to the central axis of rotation <NUM>. The short dimension <NUM> of the elongated slot <NUM> is located on a common plane with the long dimension <NUM> of the elongated slot <NUM> and is perpendicular to the long dimension <NUM>. The long dimension <NUM> of the elongated slot <NUM> defines a first distance <NUM>. The short dimension <NUM> of the elongated slot <NUM> defines a second distance <NUM>. The first distance <NUM> of the long dimension <NUM> of the elongated slot <NUM> is greater than the second distance <NUM> of the short dimension <NUM> of the elongated slot <NUM>. As such, the longest dimension of the elongated slot <NUM>, i.e., the long dimension <NUM>, extends radially relative to the central axis of rotation <NUM>, i.e., away from and/or toward the central axis of rotation <NUM>.

A retention block <NUM> is attached to and rotatable with the body <NUM>. The retention block <NUM> is positioned above the elongated slot <NUM>, proximate the outer peripheral edge <NUM> of the body <NUM>. The retention block <NUM> is fixedly secured relative to the body <NUM>. The retention bloc, may be cast and/or integrally formed with the body <NUM>, or may be securely attached to the body <NUM>, such as by welding, fasteners, permanent adhesives, etc..

As best shown in <FIG> and <FIG>, the retention block <NUM> includes a recessed surface <NUM> that is positioned against the upper surface <NUM> of the body <NUM>. The recessed surface <NUM> of the retention block <NUM> cooperates with the upper surface <NUM> of the body <NUM> to define a pocket <NUM> therebetween. The pocket <NUM> is generally aligned with and disposed over and above the elongated slot <NUM>. The pocket <NUM> includes a radially outer portion <NUM> and a radially inner portion <NUM>. The radially outer portion <NUM> of the pocket <NUM> is disposed farther from the central longitudinal axis than the radially inner portion <NUM> of the pocket <NUM>. The retention block <NUM> includes a cover portion <NUM> that partially covers the pocket <NUM> and the elongated slot <NUM> over the radially outer portion <NUM> of the pocket <NUM>. As such, the cover portion <NUM> is positioned vertically above the radially outer portion <NUM> of the pocket <NUM>. The cover portion <NUM> does not cover the radially inner portion <NUM> of the pocket <NUM>.

As best shown in <FIG> and <FIG>, the retention block <NUM> includes an access opening <NUM>. The access opening <NUM> extends from a top surface <NUM> of the retention block <NUM> to the recessed surface <NUM> of the retention block <NUM> to provide vertical access to the pocket <NUM> from above. As such, the radially inner portion <NUM> of the pocket <NUM> is open from above through the access opening <NUM>.

Referring to <FIG>, the rotary mower system <NUM> includes a pin <NUM> for securing the knife <NUM> to the mower disc <NUM>. The pin <NUM> includes a head portion <NUM> and a shank portion <NUM> extending from the head portion <NUM> to a distal end <NUM> of the shank portion <NUM>. The shank portion <NUM> passes through the elongated slot <NUM>, with the head portion <NUM> of the pin <NUM> resting on the upper surface <NUM> of the body <NUM>. The shank portion <NUM> of the pin <NUM> is moveable within the elongated slot <NUM> along a radially extending path <NUM> relative to the central axis of rotation <NUM>. The pin <NUM>, and particularly the head portion <NUM> of the pin <NUM>, is moveable between the radially outer portion <NUM> of the pocket <NUM> and the radially inner portion <NUM> of the pocket <NUM>.

The head portion <NUM> of the pin <NUM> is positioned within the pocket <NUM> between the retention block <NUM> and the body <NUM> of the mower disc <NUM>. When the pin <NUM> is disposed in the radially outer portion <NUM> of the pocket <NUM>, the cover portion <NUM> of the retention block <NUM> at least partially covers the head portion <NUM> of the pin <NUM> to prevent withdrawal or dislodgement of the pin <NUM> from the elongated slot <NUM>. When the pin <NUM> is disposed in the radially inner portion <NUM> of the pocket <NUM>, the cover portion <NUM> of the retention block <NUM> does not cover the head portion <NUM> of the pin <NUM>, thereby allowing vertical upward movement and withdrawal of the pin <NUM> from the elongated slot <NUM>.

The head portion <NUM> of the pin <NUM> defines a head width <NUM>. In one implementation, the head width <NUM> is arranged generally parallel to the short dimension <NUM> of the elongated slot <NUM>. The largest measurement or extend of the head width <NUM> of the pin <NUM> is greater than the second distance <NUM> of the short dimension <NUM> of the elongated slot <NUM>. As such, the head portion <NUM> of the pin <NUM> is unable to pass through the elongated slot <NUM>. The shank portion <NUM> of the pin <NUM> defines a diameter <NUM> that is less than the head width <NUM> of the head portion <NUM> of the pin <NUM>. The diameter <NUM> of the shank portion <NUM> of the pin <NUM> is less than the second distance <NUM> of the short dimension <NUM> of the elongated slot <NUM>. As such, the shank portion <NUM> of the pin <NUM> is able to pass through the elongated slot <NUM>.

The shank portion <NUM> of the pin <NUM> may include a circular cross-sectional shape, or a polygonal cross-sectional shape. The diameter <NUM> of the shank portion <NUM> may include a distance measured across the cross-sectional shape of the shank portion <NUM> of the pin <NUM>, whether circular or polygonal. For example, if the shank portion <NUM> is configured to include a square cross-sectional shape, then the diameter <NUM> of the shank portion <NUM> should be interpreted to include a width of the square cross-sectional shape.

As best shown in <FIG> and <FIG>, the pocket <NUM> defines a pocket width parallel to the short dimension <NUM> of the elongated slot <NUM>. The pocket width is greater than the head width <NUM> of the head portion <NUM> of the pin <NUM>. As such, the head portion <NUM> of the pin <NUM> fits within the pocket <NUM>. The access opening <NUM> of the retention block <NUM> includes an opening width that is greater than the head width <NUM> of the head portion <NUM> of the pin <NUM>. As such, the head portion <NUM> of the pin <NUM> may pass through the access opening <NUM> of the retention block <NUM>, and into the pocket <NUM>.

Referring to <FIG>, a lower support <NUM> is fixedly attached to the body <NUM> of the mower disc <NUM>. The lower support <NUM> is positioned adjacent and below the lower surface <NUM> of the body <NUM>. In the example implementation shown in the Figures and described herein, the lower support <NUM> includes a knife support portion <NUM> and a mount portion <NUM>. The mount portion <NUM> is fixedly attached to the body <NUM> of the mower disc <NUM>. The mount portion <NUM> may be attached to the body <NUM> in a suitable manner, such as but not limited to, a welded connection, a bolted connection, a permanent adhesive, etc. The knife support portion <NUM> is spaced vertically below the lower surface <NUM> of the body <NUM> to define a gap <NUM> therebetween. The knife <NUM> is positioned adjacent to the lower surface <NUM> of the body <NUM>, between the body <NUM> and the knife support portion <NUM> of the lower support <NUM>. While the example implementation shown in the Figures and described herein includes the lower support <NUM> as a separate component fixedly attached to the body <NUM> of the mower disc <NUM>, it should be appreciated that in other implementations, the lower support <NUM> may be integrally formed with the mower disc <NUM>.

As is understood by those skilled in the art, the knife <NUM> is rotatably attached to the mower disc <NUM> proximate a first end <NUM> of the knife <NUM>. Centrifugal force from rotation of the mower disc <NUM> about the central axis of rotation <NUM> urges a distal second end <NUM> of the knife <NUM> radially outward, causing the knife <NUM> to straighten and resist movement relative to the mower disc <NUM>, which provides the resistance against which crop material and/or vegetation are cut. The specific details, construction, and operation of the knife <NUM> are understood by those skilled in the art, are not pertinent to the teachings of this disclosure, and are therefore not described in greater detail herein.

The knife <NUM> is secured to the mower disc <NUM> via the pin <NUM>. More particularly, the knife <NUM> is coupled to the shank portion <NUM> of the pin <NUM>. The knife <NUM> includes a bore <NUM> extending therethrough. The shank portion <NUM> of the pin <NUM> passes through the bore <NUM> of the knife <NUM> to secure the knife <NUM> relative to the body <NUM>.

The knife support portion <NUM> of the lower support <NUM> may define a support recess <NUM>. The example implementation shown in the Figures includes the support recess <NUM> configured as a through bore <NUM> extending completely through the knife support portion <NUM> of the support. However, the support recess <NUM> may be configured differently than the example implementation. For example, the support recess <NUM> may alternatively be configured as blind bore <NUM>, which only partially extends into the knife support portion <NUM> of the lower support <NUM>. The distal end <NUM> of the shank portion <NUM> of the pin <NUM> is disposed within the support recess <NUM> when the pin <NUM> is disposed in the radially outer portion <NUM> of the pocket <NUM>.

In the example implementation shown in the Figures and described herein, the support recess <NUM> is configured to include an elongated shape. However, it should be appreciated that the support recess <NUM> may be configured differently than the example implementation described herein. As best shown in <FIG> and <FIG>, the elongated shape of the support recess <NUM> includes a long dimension and a short dimension. The long dimension of the support recess <NUM> extends radially outward from the central axis of rotation <NUM>. The short dimension of the support recess <NUM> extends perpendicular to the long dimension of the support recess <NUM>. The long dimension of the support recess <NUM> is greater than the short dimension of the support recess <NUM>. The long dimension <NUM> of the elongated slot <NUM> may be greater than the long dimension of the support recess <NUM>. The short dimension <NUM> of the elongated slot <NUM> may be approximately equal to the short dimension of the support recess <NUM>.

The diameter <NUM> of the shank portion <NUM> of the pin <NUM> is less than the short dimension <NUM> of the support recess <NUM>. As such, the shank portion <NUM> of the pin <NUM> may pass through the support recess <NUM>. The pin <NUM> may be moveable within the support recess <NUM> as the head portion <NUM> of the pin <NUM> moves between the radially inner portion <NUM> of the pocket <NUM> and the radially outer portion <NUM> of the pocket <NUM>.

Referring to <FIG>, the rotary mower system <NUM> may further include an upper plate <NUM>. The upper plate <NUM> is moveably attached to the body <NUM> for movement between an engaged position, best shown in <FIG>, and a disengaged position, best shown in <FIG>. When the upper plate <NUM> is disposed in the engaged position, the upper plate <NUM> covers the access opening <NUM> of the retention block <NUM>, thereby covering the radially inner portion <NUM> of the pocket <NUM>. When the upper plate <NUM> is disposed in the disengaged position, the upper plate <NUM> does not cover the access opening <NUM> of the retention block <NUM>, thereby allowing access to the pocket <NUM> through the access opening <NUM> from above.

In the example implementation shown in the Figures and described herein, the upper plate <NUM> includes resilient spring steel plate that is rotatably attached to the body <NUM> of the mower disc <NUM>. As used herein, the term "resilient" is defined as "able to recoil or spring back into shape after bending, stretching, or compressing". As such the upper plate <NUM> is configured and/or able to spring back into an original or initial shape in response to bending, stretching, or compression of a component or portion thereof.

In the example implementation shown in the Figures and described herein, the upper plate <NUM> is rotatably attached for pivotal or rotational movement relative to the body <NUM>, between the engaged position, best shown in <FIG>, and the disengaged position, best shown in <FIG>. The upper plate <NUM> includes a planar portion <NUM> having a plate thickness <NUM>, and a bushing <NUM> seated within the planar portion <NUM> and having a bushing thickness <NUM>. The bushing thickness <NUM> of the bushing <NUM> is greater than the plate thickness <NUM> of the planar portion <NUM> of the upper plate <NUM>, such that the bushing <NUM> stands proud of the planar portion <NUM>. A first fastener <NUM> passes through the planar portion <NUM> and the bushing <NUM>, and is secured relative to the body <NUM>. In the example implementation shown in the Figures and described herein, the first fastener <NUM> attaches both the upper plate <NUM> and the lower support <NUM> to the mower disc <NUM>. As second fastener <NUM> further attaches the lower support <NUM> to the mower disc <NUM>. The upper plate <NUM> may rotate relative to the body <NUM> of the mower disc <NUM> about an axis defined by the first fastener <NUM>. Because the bushing <NUM> stands proud of the planar portion <NUM> of the upper plate <NUM>, the upper plate <NUM> is not pinched or bound by the first fastener <NUM>, and is thereby allowed to rotate between the engaged position and the disengaged position. It should be appreciated that the upper plate <NUM> and the manner of attachment to the mower disc <NUM> may differ from the example implementation shown in the figures and described herein.

As best shown in <FIG>, the upper plate <NUM> may include a protrusion <NUM>. The protrusion <NUM> may be shaped to nest within and penetrate into the access opening <NUM> of the retention block <NUM>. The protrusion <NUM> may further penetrate into the radially inner portion <NUM> of the pocket <NUM>. When the upper plate <NUM> is disposed in the engaged position, the protrusion <NUM> may be engaged within the access opening <NUM>. The protrusion <NUM> is withdrawn from the access opening <NUM> when the upper plate <NUM> is disposed in the disengaged position.

A method of attaching the knife <NUM> to the mower disc <NUM> is also provided. The method includes providing the mower disc <NUM> to include the elongated slot <NUM> and the retention block <NUM> described above. In order to install the knife <NUM>, the upper plate <NUM> is bent vertically upward and away from the mower disc <NUM>. Bending the upper plate <NUM> upward and away from the mower disc <NUM> dislodges the protrusion <NUM> of the upper plate <NUM> from interlocking engagement with the access opening <NUM> of the retention block <NUM>. Once the protrusion <NUM> is dislodged from the access opening <NUM> of the retention block <NUM>, the upper plate <NUM> may be moved relative to the mower disc <NUM>, from the engaged position into the disengaged position, such as shown in <FIG>. Moving the upper plate <NUM> into the disengaged position provides access to the access opening <NUM> from above the mower disc <NUM>. The upper plate <NUM> may be moved from the engaged position to the disengaged position by rotating the upper plate <NUM> about an axis <NUM> defined by the first fastener <NUM>.

With the upper plate <NUM> disposed in the disengaged position, the knife <NUM> may be positioned between the lower surface <NUM> of the body <NUM> and the lower support <NUM> attached to the body <NUM>. When properly positioned, the bore <NUM> of the knife <NUM> is aligned with the elongated slot <NUM> of the mower disc <NUM> and the support recess <NUM> of the lower support <NUM>.

With the knife <NUM> properly positioned, the shank portion <NUM> of the pin <NUM> may be aligned relative to the retention block <NUM>. In the example implementation described herein, with reference to <FIG>, the shank portion <NUM> is aligned to form an insertion angle <NUM> relative to the central axis of rotation <NUM>. The shank is aligned to pass through the radially inner portion <NUM> of the pocket <NUM> at the insertion angle <NUM>. The insertion angle <NUM> may vary. In one implementation, the insertion angle <NUM> may include an angle between twenty degrees (<NUM>°) and seventy degrees (<NUM>°). The pin <NUM> is positioned to pass through the access opening <NUM> of the retention block <NUM>, the radially inner portion <NUM> of the pocket <NUM>, the elongated slot <NUM>, the bore <NUM> of the knife <NUM>, and the support recess <NUM> of the lower support <NUM>.

Once the pin <NUM> is properly aligned, the pin <NUM> may be inserted through the access opening <NUM> of the retention block <NUM>, the radially inner portion <NUM> of the pocket <NUM>, the elongated slot <NUM>, and the bore <NUM> of the knife <NUM> until the head portion <NUM> of the pin <NUM> contacts the upper surface <NUM> of the body <NUM>. In the example implementation described herein, because the shank portion <NUM> of the pin <NUM> is aligned at the insertion angle <NUM>, the head portion <NUM> of the pin <NUM> will not rest flat against the upper surface <NUM> of the body <NUM> when the pin <NUM> is initially inserted through the elongated slot <NUM>. Rather, once the head portion <NUM> of the pin <NUM> contacts the upper surface <NUM> of the body <NUM>, the pin <NUM> may be rotated from the insertion angle <NUM> to vertical position in which the shank portion <NUM> of the pin <NUM> is substantially parallel the central axis of rotation <NUM>. Once the pin <NUM> is disposed in the vertical position, such as shown in <FIG>, the head portion <NUM> of the pin <NUM> may substantially rest flat against the upper surface <NUM> of body <NUM> of the mower disc <NUM> proximate the radially inner portion <NUM> of the pocket <NUM>. Additionally, once the pin <NUM> is rotated into the vertical position, the distal end <NUM> of the shank portion <NUM> will extend into or at least partially penetrate into the support recess <NUM> of the lower support <NUM>.

While the example implementation described herein includes aligning the pin <NUM> at the insertion angle <NUM> and rotating the pin <NUM> from the insertion angle <NUM> into the vertical position, it should be appreciated that in other embodiments, the pin <NUM> may be initially aligned in a vertical orientation, i.e., parallel with the central axis of rotation <NUM>, and inserted through the access opening <NUM> of the retention block <NUM>, the radially inner portion <NUM> of the pocket <NUM>, the elongated slot <NUM>, and the bore <NUM> of the knife <NUM>, and into the support recess <NUM> by simply moving the pin <NUM> vertically downward, thereby eliminating the need to rotate the pin <NUM> from the insertion angle <NUM> into the vertical position.

Once the pin <NUM> is arranged in the vertical position, with the head portion <NUM> disposed in the radially inner portion <NUM> of the pocket <NUM>, and with the shank portion <NUM> extending through the elongated slot <NUM> of the mower disc <NUM>, the bore <NUM> of the knife <NUM>, and into the support recess <NUM> of the lower support <NUM>, the pin <NUM> is then moved relative to the body <NUM> of the mower disc <NUM> in a direction radially outward and away from the central axis of rotation <NUM>. The pin <NUM> is moved radially outward so that the head portion <NUM> of the pin <NUM> is disposed in the radially outer portion <NUM> of the pocket <NUM>, such as shown in <FIG>. With the head portion <NUM> of the pin <NUM> disposed in the radially outer portion <NUM> of the pocket <NUM>, the cover portion <NUM> of the retention block <NUM> at least partially covers the head portion <NUM> of the pin <NUM> to prevent upward vertical movement and withdrawal of the pin <NUM> from the elongated slot <NUM>.

With the head portion <NUM> of the pin <NUM> disposed in the radially outer portion <NUM> of the pocket <NUM>, movement of the pin <NUM> along the elongated slot <NUM> in a direction radially inward and toward the central axis of rotation <NUM> may be blocked to secure the pin <NUM> relative to the body <NUM>. With movement of the pin <NUM> in the inward radial direction blocked, the head portion <NUM> of the pin <NUM> is unable to move into the radially inner portion <NUM> of the pocket <NUM>, and therefore cannot be removed from the pocket <NUM>.

Blocking movement of the pin <NUM> along the elongated slot <NUM> in the direction radially inward and toward the central axis of rotation <NUM> may include moving the upper plate <NUM> from the disengaged position, shown in <FIG>, into the engaged position, shown in <FIG>. The upper plate <NUM> is moved relative to the mower disc <NUM> so that the protrusion <NUM> is aligned with the access opening <NUM>. It should be appreciated that moving the upper plate <NUM> from the disengaged position into the engaged position may include bending the upper plate <NUM> vertical upward so that the protrusion <NUM> of the upper plate <NUM> clears the retention block <NUM> and then rotating the upper plate <NUM> until the protrusion <NUM> is aligned above the access opening <NUM> in the retention block <NUM>. A downward spring force generated by bending the upper plate <NUM> vertically upward may then bias the upper plate <NUM> downward and move the protrusion <NUM> into interlocking engagement with the access opening <NUM>. With the upper plate <NUM> covering the access opening <NUM> and the protrusion <NUM> disposed in the access opening <NUM> and/or extending into the radially inner portion <NUM> of the pocket <NUM>, movement of the head portion <NUM> of the pin <NUM> toward the central axis of rotation <NUM> is blocked and the knife <NUM> is secured relative to the body <NUM> of the mower disc <NUM>.

It should be appreciated that removal of the knife <NUM> from the mower disc <NUM> may be accomplished by performing the above described installation procedure in reverse operation.

Claim 1:
A rotary mower system (<NUM>) comprising:
a mower disc (<NUM>) having a body (<NUM>) rotatable about a central axis of rotation (<NUM>), the body (<NUM>) including an upper surface (<NUM>) and a lower surface (<NUM>) positioned beneath and opposite the upper surface (<NUM>);
wherein the body (<NUM>) extends radially outward from the central axis of rotation (<NUM>) and defines an elongated slot (<NUM>) passing therethrough, between the upper surface (<NUM>) and the lower surface (<NUM>);
a retention block (<NUM>) attached to and rotatable with the body (<NUM>), wherein the retention block (<NUM>) includes a recessed surface (<NUM>) positioned against the upper surface (<NUM>) of the body (<NUM>) and cooperating with the upper surface (<NUM>) to define a pocket (<NUM>) therebetween, the pocket (<NUM>) including a radially outer portion (<NUM>) and a radially inner portion (<NUM>);
wherein the retention block (<NUM>) includes a cover portion (<NUM>) at least partially covering the elongated slot (<NUM>) over the radially outer portion (<NUM>) of the pocket (<NUM>);
a pin (<NUM>) having a shank portion (<NUM>) passing through the elongated slot (<NUM>), wherein the shank portion (<NUM>) of the pin (<NUM>) is moveable within the elongated slot (<NUM>) along a radially extending path (<NUM>) relative to the central axis of rotation (<NUM>) between the radially outer portion (<NUM>) of the pocket (<NUM>) and the radially inner portion (<NUM>) of the pocket (<NUM>);
wherein the pin (<NUM>) includes a head portion (<NUM>) attached to the shank portion (<NUM>), with the head portion (<NUM>) positioned within the pocket (<NUM>) between the retention block (<NUM>) and the body (<NUM>) of the mower disc (<NUM>), such that the cover portion (<NUM>) of the retention block (<NUM>) at least partially covers the head portion (<NUM>) of the pin (<NUM>) to prevent withdrawal of the pin (<NUM>) from the elongated slot (<NUM>) when the pin (<NUM>) is disposed in the radially outer portion (<NUM>) of the pocket (<NUM>), and wherein the cover portion (<NUM>) does not cover the head portion (<NUM>) of the pin (<NUM>) when the pin (<NUM>) is disposed in the radially inner portion (<NUM>) of the pocket (<NUM>) to allow vertical movement of the pin (<NUM>) relative to the body (<NUM>); and
a knife (<NUM>) positioned adjacent the lower surface (<NUM>) of the body (<NUM>) and coupled to the shank portion (<NUM>) of the pin (<NUM>).