Cutting unit for rotary lawn mowers

Claim 2

In a lawn mower, a power driven shaft; a disc having a plurality of apertures; a plate having proturberances thereon for matching relation with some of said apertures; said disc and plate being matched and removably affixed to said shaft; a plurality of grass cutting blade elements pivotally mounted along the periphery of said disc and extending radially of said disc upon rotation thereof; each of said blade elements comprising a linear portion and a portion offset therefrom, said portions having apertures aligned along an axis perpendicular to said linear portion; said portions being disposed in straddling relation to the periphery of said disc with the linear portion below and the offset portion above the disc and with the apertures in said portions in alignment with another of said apertures in said disc; a pivot pin inteRconnecting the apertures in said portions and in the periphery of said disc; said linear portion and said offset portion closely surrounding said pivot pin in their respective apertures to support said pivot pin substantially perpendicular to said linear portion, said other aperture in said disc being sufficiently larger than the diameter of said pivot pin to allow said pivot pin and blade element to tilt with respect to said disc, said disc when rotated by said power driven shaft setting up a centrifugal force which yieldingly causes each blade element to be extended radially outwardly and substantially parallel to said disc with the pivot pin normal to said disc and to said linear portion of said blade element, and detachable means engagable with said pivot pin for positively retaining said pivot pin in said apertures of said linear and offset portions.

Claim 3

A device according to claim 1, wherein the protuberances in the plate are spaced substantially parallel flanges and the apertures in the disc are correspondingly spaced parallel slots.

Claim 4

A device according to claim 1, wherein the protuberances in the plate are substantially radially aligned studs and the opertures in the disc are correspondingly radially aligned.

Claim 5

A device according to claim 3, wherein the studded plate is disposed in intervening relation between the disc and the shaft to which it is affixed.

Claim 6

A device according to claim 3, wherein the disc is disposed in intervening relation between the plate and the shaft to which it is affixed.

Claim 7

A device according to claim 1, wherein the offset portion of said blade element gradually diverges toward the aperture thereof, whereby, upon deflection of the blade, the divergent portion will cammingly engage the disc.

Claim 8

A device according to claim 1, wherein each said cutting blade element is provided with a leading cutting edge and a trailing upwardly disposed clippings deflecting flange.

Claim 9

A device according to claim 1, wherein each said blade element is of plastic or other synthetic material.

Claim 10

A cutting unit for a rotary lawn mower which has at least one depending, vertical, driven shaft comprising a central substantially planar mounting plate having means for centrally attaching said plate to the driven shaft of the lawn mower and apertures provided along the periphery of the mounting plate, a plurality of grass cutting blade units pivotally mounted along the periphery of said mounting plate and extending radially outwardly of said plate upon rotation thereof, each of said blade units comprising a linear blade portion having inner and outer ends, and an offset strap portion secured to the linear portion intermediate the ends thereof and extending in overlying relation to the inner end of the linear blade portion, aligned apertures in the overlying offset strap portion and linear blade portion, said portions being disposed in straddling relation to the periphery of said mounting plate and in alignment with one of the apertures in said mounting plate, pivot pin means extending through the apertures in said offset and linear portions. perpendicular to said linear portion and through said one of the apertures in the periphery of said mounting plate for pivotally securing said blade unit to said mounting plate, and quick disconnect means for positively locking said pivot pin means in position extending through said apertures in said offset and linear portions and said one of the apertures in said mounting plate, said pivot pin means being loosely fitted in said one of the apertures in said mounting plate to permit said pivot pin means and said blade unit to tilt relative to said mounting plate whereby when said cutting unit is mounted on said shaft and is still, the blade unit slopes downardly from the periphery of the mounting plate under its own weight, and when said cutting unit is rotated by said shaft, centrifugal force acting on said blade unit will tilt the blade unit and pivot pin means until the blade portion Of the blade unit is parallel to the mounting plate and extends radially outwardly therefrom.

Claim 11

A cutting unit for a rotary lawn mower which has at least one depending, vertical, driven shaft comprising a central substantially planar mounting plate having means for centrally attaching said plate to the driven shaft of the lawn mower and apertures provided along the periphery of the mounting plate, a plurality of grass cutting blade units pivotally mounted along the periphery of said mounting plate and extending radially outwardly of said plate upon rotation thereof, each of said blade units comprising a linear blade portion having inner and outer ends, and an offset strap portion secured to the linear portion intermediate the ends thereof and extending in overlying relation to the inner end of the linear blade portion, aligned apertures in the overlying offset strap portion and linear blade portion, said portions being disposed in straddling relation to the periphery of said mounting plate and in alignment with one of the apertures in said mounting plate, pivot pin means extending through the apertures in said offset and linear portions. perpendicular to said linear portion and through said one of the apertures in the periphery of said mounting plate for pivotally securing said blade unit to said mounting plate, and quick disconnect means for positively locking said pivot pin means in position extending through said apertures in said offset and linear portions and said one of the apertures in said mounting plate, said pivot pin means being loosely fitted in said one of the apertures in said mounting plate to permit said pivot pin means and said blade unit to tilt relative to said mounting plate whereby when said cutting unit is mounted on said shaft and is still, the blade unit slopes downardly from the periphery of the mounting plate under its own weight, and when said cutting unit is rotated by said shaft, centrifugal force acting on said blade unit will tilt the blade unit and pivot pin means until the blade portion Of the blade unit is parallel to the mounting plate and extends radially outwardly therefrom.

Claim 12

A cutting unit according to claim 9 wherein the linear portion of each blade unit is provided with a leading cutting edge and a trailing upwardly disposed clippings deflecting flange.