Safe cutter disc assembly for rotary lawn mower

A safe cutter disc assembly for a rotary lawn mower comprising, in combination, a disc having a circular central portion and an annular outer portion, the annular outer portion being downwardly offset and connected to the central portion by means of a shallow vertically extending wall, a plurality of evenly spaced radially extending openings being provided in the wall, cutter pins registered in the respective openings, said cutter pins being formed of durable plastic, each pin having an enlarged head with a relatively stiff shank, the shank adjacent the head being dimensioned to fit in the opening, each pin having a long tapering flexible tip portion, the wall of the disc having substantial radial thickness for rigid support of the pins cantilever fashion, the wall of the disc having a relatively shallow vertical dimension so that the annular outer portion of the disc closely underlies and protects the relatively stiff shank portions of the pins while the tips of the pins project beyond the periphery of the disc into cutting engagement with the grass and are free to bend back into the protection of the annular outer portion of the disc upon striking of an obstruction, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the wall of the disc as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower comprising, in combination, a disc having a circular central portion and an annular outer portion, the annular outer portion being downwardly offset and connected to the central portion by means of a shallow vertically extending wall, a plurality of radially extending openings being provided in the wall, cutter pins registered in the respective openings, said cutter pins being formed of durable plastic, each pin having a head with a relatively stiff shank dimensioned to fit in the opening and having a long tapering tip portion, the wall of the disc having substantial radial thickness with rigid support of the pins cantilever fashion, the openings being formed in the base of the wall so that the annular outer portion of the disc closely underlies and protects the relatively stiff shank portions of the pins while the tips of the pins project beyond the periphery of the disc into cutting engagement with the grass and are free to bend backwardly into the protection of the annular outer portion of the disc upon striking of an obstruction, and backstop means in the form of an upstanding radial vane on the annular outer portion of the disc adjacent each of the openings, each vane having a retreating curvature for engaging and providing lengthwise-distributed support for the associated pin during its backward bend so that stress in the pin is kept substantially within the elastic limit, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the wall of the disc as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower of the type having a shallow inverted enclosure comprising, in combination, a disc having a central opening and molded of resiliently deformable plastic, the disc having a circular central portion and an annular outer portion, the annular outer portion being downwardly offset and connected to the central portion by means of a shallow vertically extending wall, a plurality of spaced radially extending openings being provided in the wall, cutter pins registered in the respective openings, said cutter pins being formed of durable plastic, each pin having a head and a relatively stiff shank, the shank adjacent the head being dimensioned to fit in the opening, each pin having a long tapering tip portion, the openings being located immediately above the top surface of the annular outer portion of the disc so that such portion closely underlies and protects the relatively stiff shank portions of the pins while the tips of the pins project beyond the periphery of the disc into cutting engagement with the grass and are free to bend back into the protection of the annular portion of the disc upon striking of an obstruction, the annular portion being of substantially thinner cross section than the central portion or the wall, and backstop means in the form of an upstanding radial vane adjacent each of the openings and integrally secured to the wall and to the annular portion for reinforcement of the latter, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the wall of the disc as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A cutter disc assembly for a rotary lawn mower comprising, in combination, a disc formed of resiliently deformable plastic having a circular central portion and an annular outer portion surrounding the same, the disc having an axially offset wall portion at the junction between the central portion and the annular outer portion, the offset wall portion providing a plurality of radially extending openings evenly spaced therein, cutter pins registered in the openings, the cutter pins being formed of durable plastic, each pin having a head and a relatively stiff shank, the shank adjacent the head being dimensioned to fit in the opening, each pin having a long tapering tip portion which is flexible and resilient, the wall having substantial radial thickness for rigid support of the pins cantilever fashion, the annular outer portion of the disc closely underlying the relatively stiff shanks of the pins with the tips of the pins projecting radially outwardly from the periphery of the disc for cutting of the grass as the disc is rotated but with the tip portions of the pins being free to bend backwardly into the protective confines of the annular portion of the disc upon striking of an obstruction, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the wall of the disc as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower of the type having a shallow inverted enclosure including an encircling sidewall with driving means including a drive shaft extending downwardly into the enclosure comprising, in combination, a disc integrally molded of resiliently deformable plastic having a central opening for connection to the drive shaft, the disc having a circular central portion, a shallow vertically extending wall, and an annular outer portion extending outwardly from the wall, a plurality of evenly spaced radially extending openings being provided in the wall, cutter pins inserted in the openings, said cutter pins being formed of durable plastic, each pin having a head and a relatively stiff shank, the shank adjacent the head being dimensioned to fit in the opening and each pin having a long flexible tip portion, the tip portion being of sharp conical shape tapering at a substantially constant rate from the shank to the tip, the shank having a cross sectional area at least about four times greater than the area of the tip, the pins having a length of at least about one and one-half times the radial width of the annular outer portion of the disc, the wall of the disc having a relatively shallow vertical dimension so that the annular outer portion of the disc closely underlies and protects the relatively stiff shank portion of each pin while the tips of the pins project beyond the annular outer portion of the disc for engagement with the grass and are free to bend back toward the protection of the annular outer portion of the disc upon striking of an obstruction, and backstop means in the form of an upstanding radial vane on the annular outer portion of the disc adjacent each of the openings, the vane having a retreating curvature for engaging and providing lengthwise-distributed support for the associated pin during its backward bend, the outer extremity of the vane being spaced inwardly by a small amount from the periphery of the disc to accommodate the backward bend of the pin, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the wall of the disc as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower of the type having a frame and driving means including a drive shaft extending downwardly from the frame comprising, in combination, a disc integrally molded of resiliently deformable plastic having a central opening for connection to the drive shaft, the disc having a central portion, a shallow vertically extending wall, and an annular outer portion outwardly of the wall, a radially extending opening being formed in the wall, a cutter pin inserted in the opening, said cutter pin being formed of durable plastic having a head, a shank portion and a flexible tip portion, the pin having a length of at least about one and one-half times the radial dimension of the annular outer portion of the disc, the wall of the disc having a relatively shallow vertical dimension and the opening therein being formed adjacent the base of the wall so that the annular outer portion of the disc closely underlies and protects the shank portion of the pin while the tip portion projects beyond the annular outer portion of the disc for engagement with the grass, with freedom to bend back toward the protection of the annular outer portion of the disc upon striking of an obstruction, and backstop means in the form of an upstanding projection on the annular outer portion of the disc immediately adjacent the downstream side of the opening, the projection being shaped to provide progressive lengthwise-distributed support for the associated pin during its backward bend thereby to avoid concentration of bending stress in the shank portion of the pin, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the wall of the disc as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A cutting assembly for a rotary mower, comprising:

• a. a cutting element carrier having a central portion, an outer portion attached to and located radially outwardly from the central portion, and cantilever mounting means located at the junction between the central and outer portion for securing a cutting element to the cutting element carrier approximately on a radius of the carrier in a cantilever manner;
• and
• b. the cutting element being flexible and resilient and having a shank portion, an outer tip, and a tapered portion interposed between the shank portion and the outer tip, the shank portion having a substantially larger cross sectional area than the tip, the shank portion being secured to the carrier by the cantilever means, whereby the tapered portion assumes a curvature having an ever increasing rate when a force is applied at the tip of the cutting element with the shank portion being cantilever mounted;
• c. the cantilever mounting means locating the cutting element above and adjacent to the outer portion of the carrier;
• d. the cutting element having a length sufficient so that the tip thereof extends beyond the periphery of the outer portion, thereby defining a tip extension, in the region of the cutting element when the shank portion is secured by the cantilever mounting means
• e. the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the cantilever mounting means as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower comprising, in combination, a disc having a central portion and an annular outer portion surrounding the same, the disc having an axially offset wall portion at the junction between the central portion and the outer portion, a plurality of radially extending openings being provided in the wall, cutter pins registered in the respective openings, said cutter pins being formed of durable highly resilient plastic, each pin having a head with an adjacent shank dimensioned to fit in the opening and having a long flexible tip portion, the wall of the disc having substantial radial thickness for rigid support of the pins cantilever fashion, the openings being formed in the base of the wall and the wall being spaced substantially inwardly from the periphery so that the annular outer portion of the disc closely underlies and protects the shank portions of the pins while the tips of the pins project beyond the periphery of the disc into cutting engagement with the grass and are free to bend backwardly toward the protection of the annular outer portion of the disc upon striking of an obstruction, and an upstanding radial backstop on the annular outer portion of the disc adjacent each of the openings, each backstop presenting a retreating curvature for engaging and providing lengthwise-distributed support for the associated pin during its backward bend, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the wall of the disc as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower of the type having a frame and driving means including a drive shaft extending downwardly from the frame comprising, in combination, a disc having a central opening for connection to the drive shaft, the disc having a central portion and an annular outer portion of thin cross section, a cutter pin having a head, a shank portion and a flexible tip portion, means for securing the pin to the disc, the securing means being spaced substantially inwardly from the periphery of the disc, the securing means having a provision for engaging the shank of the pin so that the tip portion of the pin extends beyond the disc periphery for engagement with the grass, the securing means further having provision for holding the shank cantilever fashion in a radial position to prevent bodily swinging of the pin while permitting flexing of the tip portion in response to reaction force, the securing means and pin being so located that the annular outer portion of the disc closely underlies and protects the pin while permitting the pin to bend back toward the protection of the annular outer portion of the disc upon striking of an obstruction, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the securing means as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower having a vertical drive shaft comprising, in combination, a disc having a provision for connection to the lower end of the drive shaft, the disc having an annular outer portion presenting a generally flat surface on its underside, at least one cutter pin on said disc arranged generally radially thereon, each pin being made of tough, resilient abrasion-resistant material and having a head and a shank and terminating in a long flexible tip portion, mounting means on the disc for engaging and supporting the shank of each pin cantilever-fashion adjacent the head and at a region which is spaced inwardly from the periphery of the disc so that only the tip portion of the pin projects radially outwardly of the periphery for cutting of the grass as the disc is rotated, the disc having a smoothly curved backstop surface arranged in the path of backward bending movement of the shank of the pin as the tip portion of the pin yields upon striking of an obstruction encountered radially of the disc, substantially the entire shank of the pin being spaced upwardly from the underside of the outer portion of the disc and generally parallel thereto so that the shank of the pin is shielded against obstructions axially engaging the underside of the disc, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the mounting means as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower having a vertical drive shaft comprising, in combination, a disc having provision for connection to the lower end of the drive shaft, the disc having an annular outer portion presenting a generally flat surface on its underside, at least one cutter pin on said disc arranged generally radially thereon, each pin being made of tough, resilient abrasion-resistant material and having a head and a shank and terminating in a long flexible tip portion, mounting means on the disc engaging and supporting the shank of each pin cantilever-fashion adjacent the head and at a region which is spaced inwardly from the periphery of the disc so that only the tip portion of the pin projects radially outwardly of the periphery for cutting of the grass as the disc is rotated, the disc having a smoothly curved backstop surface arranged in the path of backward bending movement of the shank as the tip of the pin yields upon striking an obstruction encountered radially of the disc, the backstop surface effectively terminating at a point adjacent to but spaced inwardly of the periphery of the disc so that upon striking of the radial obstruction the tip portion of the pin is free to move into the protective confines of the outer portion of the disc, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the mounting means as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower having a vertical drive shaft comprising, in combination, a disc having provision for connection to the lower end of the drive shaft, the disc having an annular outer portion presenting a shallow conical surface on its underside, at least one cutter pin on said disc arranged generally radially thereon, each pin being made of tough, resilient abrasion-resistant material and having a head and a shank and terminating in a long flexible tip portion, mounting means on the disc for engaging and supporting the shank of each pin cantilever-fashion adjacent the head and at a region which is spaced inwardly from the periphery of the disc so that only the tip portion of the pin projects radially outwardly of the periphery for cutting of the grass as the disc is rotated, the disc having a smoothly curved backstop surface arranged in the path of backward bending movement of the shank of the pin as the tip of the pin yields upon striking of an obstruction encountered radially of the disc, the backstop surface being positioned inwardly of the periphery of the disc so that upon striking of the radial obstruction the tip portion of the pin is free to move into the protective confines of the disc, substantially the entire shank of the pin being spaced upwardly from the underside of the outer portion of the disc and generally parallel thereto so that the shank of the pin is shielded against obstructions axially engaging the underside of the disc, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the mounting means as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing oepration at conventional rotative speeds on the order of 3000 rpm.

A safe cutter disc assembly for a rotary lawn mower having a vertical drive shaft comprising, in combination, a disc having a central portion with provision for connection to the lower end of the drive shaft and a peripheral portion presenting a generally flat surface on its underside, at least one cutter pin on said disc arranged generally radially thereon, each pin being made of tough, resilient abrasion-resistant plastic and having a head and a stiff shank and terminating in a stiffly resilient tip portion, mounting means on the disc for engaging and supporting the shank of each pin cantilever-fashion adjacent the head so that only the tip portion of the pin projects radially outwardly of the periphery for cutting of the grass as the disc is rotated, the mounting means being spaced sufficiently inwardly of the periphery so that as the pin strikes a major obstruction radially of the disc the pin may bend relatively harmlessly about its mounting means into an inwardly bent position in which the pin is increasingly shielded by the disc, and means for causing curvature to be smoothly distributed in the shank with avoidance of any sharply concentrated stress in the pin as the tip portion of the pin strikes the obstruction, substantially the entire shank of the pin being spaced upwardly from the underside of the peripheral portion of the disc and generally parallel thereto so that the shank of the pin is shielded against obstructions axially engaging the underside of the disc, the pin being of sufficiently thick dimension over the shank portion that the pin is supported beam-like adjacent its head end, in radial position by the mounting means as the disc revolves during mowing free from reliance upon centrifugal force to hold the pin outwardly in cutting engagement with the grass and thus capable of performing a typical mowing operation at conventional rotative speeds on the order of 3000 rpm.