Rotary-type lawnmower

In a rotary-type lawnmower having a wheeled chassis adapted to travel over vegetation-covered ground's surface and carrying a prime mower for rotating a downwardly-extending driveshaft, the improvement comprising:

• (a) a disc-like head member mounted on said driveshaft for rotation about a vertical axis relative to the ground's surface;
• (b) said head member having a peripheral circular rim and carrying aperture means at equal angular spacings about said head member;
• (c) non-metallic flexible elongated cutting pins carried on said head member and passing through said aperture means, said cutting pins having tapered free-traveling end portions extending radially outwardly from said circular rim on said head member to cutting ends at a cutting plane which resides substantially perpendicular to the vertical axis;
• (d) mounting means on said head member for releasably securing said cutting pins by an enlarged part against unintended radial and angular displacement from said aperture means;
• (e) support means on said head member adjacent said circular rim for supporting said cutting pins against vertical deflection of said free-traveling end portions resulting from contact with vegetation being cut, whereby said cutting ends on said free-traveling end portions remain in the cutting plane for cutting vegetation at a uniform height above the ground's surface.

In a rotary-type lawnmower having a wheeled chassis adapted to travel over vegetation-covered ground's surface and carrying a prime mover for rotating a downwardly-extending driveshaft, the improvement comprising:

• (a) a disc-like head member of rigid material mounted on said driveshaft for rotation about a vertical axis relative to the ground's surface;
• (b) said head member having a continuous peripheral circular rim and carrying aperture means at equal angular spacings about said head member, said head member having a smooth and continuous lower surface, and said rim and lower surface being substantially free of significant projections or recesses capable of impact injury to human parts when said head member is rotated at operative speeds;
• (c) non-metallic flexible elongated cutting pins carried on said head member and passing through said aperture means, said cutting pins having tapered free-traveling end portions extending radially outwardly from said circular rim on said head member to cutting ends at a cutting plane which resides substantially perpendicular to the vertical axis, said cutting pins having a length at least 20 times their maximum width at said cutting end in contact with vegetation being cut;
• (d) mounting means on said head member for releasably securing said cutting pins at an enlarged part against unintended radial displacement from said aperture means and said cutting pins projecting in said free-traveling portions either in a plane parallel to said cutting plane or downwardly at an angle not in excess of about 10 degrees relative to said cutting plane;
• (e) support means on said head member adjacent said circular rim for supporting said cutting pins between about 30 and about 70 percent of their length substantially against vertical deflection of said free-traveling end portions resulting from contact with vegetation being cut, whereby said cutting ends on said free-traveling end portions remain in the cutting plane for cutting vegetation at a uniform height above the ground's surface.

A cutting pin for use in a rotary-type vegetation cutting device, comprising:

• (a) an elongated cutting pin formed monolithically of a flexible and non-metallic polymeric material;
• (b) said cutting pin having a first portion providing supporting surfaces and thereon an enlarged part as a securing means, and said first portion comprising between about 30 and about 70 percent of the length of said cutting pin;
• (c) said cutting pin having a cutting end with an intervening free-traveling end portion between said cutting end and said first portion, and said free-traveling end portion having a taper from said first portion to said cutting end;
• and
• (d) said cutting end having a transverse dimension between about 0.060 and about 0.125 inches with the length of said cutting pin being at least 20 times said transverse dimension wherein said free-traveling end portion remains sufficiently rigid to cut vegetation at a uniform height when traveling in a rotational path at a tip speed of said cutting end of approximately 14,000 to 30,000 feet per minute and may be subject to unsupported deflection sufficient to pass by an object struck by said cutting end without breaking said cutting pin.

A cutting pin for use in a rotary-type vegetation cutting device, comprising:

• (a) an elongated cutting pin having a first portion extending lengthwise along said cutting pin and forming supporting surface means for supporting said cutting pin in a passageway formed in a rotary head member of said device;
• (b) said cutting pin having a cutting end with an intervening free traveling end portion between said cutting end and said first portion, said free traveling end portion being tapered radially outward from said first portion to said cutting end and being adapted to extend unsupported radially beyond the periphery of said head member;
• and
• (c) said cutting pin being formed as a monolithic polymeric member and with transverse and lengthwise dimensions of said free traveling end portion which will provide sufficient rigidity when rotating with said head member to cut vegetation at a substantially uniform height and which will permit deflection of said free traveling end portion sufficiently upon striking a rigid object in the path of said cutting pin offering greater resistance to movement than said vegetation to permit said cutting end to pass by said object.

In a rotary-type lawnmower having a chassis adapted to travel over vegetation-covered ground and carrying a prime mover for rotating a downwardly-extending vertical driveshaft, the improvement comprising:

• (a) a head member mounted on said drive shaft for rotation about a vertical axis relative to the ground's surface;
• and
• (b) a plurality of non-metallic, elongated cutting pins carried on said head member circumferentially spaced apart one from the other and extending generally radially outward from said axis, each said cutting pin having a first portion extending lengthwise of said cutting pin and supported by cooperating support means on said head member, each said cutting pin having a second portion extending lengthwise of said cutting pin from said first portion and radially outward beyond the periphery of said head member to an unsupported distal end of said cutting pin, and each said cutting pin being formed of an elastic material and with transverse and lengthwise dimensions of said second portion which will provide sufficient rigidity of said second portion to cut vegetation at a substantially uniform height when rotating said head member at a tip speed of said end of approximately 14,000 to 30,000 feet per minute, and which will permit deflection of said second portion sufficient upon striking a rigid object in the path of said cutting pin offering greater resistance to movement than said vegetation to pemit said end to pass by said object.

In a rotary-type lawnmower having a chassis adapted to travel over vegetation-covered ground and carrying a prime mover for rotating a downwardly-extending vertical driveshaft, the improvement comprising:

• (a) a head member mounted on said drive shaft for rotation about a vertical axis relative to the ground's surface;
• (b) a plurality of non-metallic, elongated cutting pins carried on said head member circumferentially spaced apart one from the other and extending generally radially outward from said axis, each said cutting pin having a first portion extending lengthwise along said cutting pin and supported in cooperating support means on said head member including a circumferentially spaced apart radially extending passageway for receiving said first portion, each said cutting pin having a second portion extending lengthwise of said cutting pin from said first portion and tapered radially outward from said support means on said head member to a distal end of said cutting pin, at least part of said second portion including said end extending radially beyond the periphery of said head member;
• and
• (c) each said cutting pin being formed as a monolithic polymeric member and with transverse and lengthwise dimensions of said second portion which will provide sufficient rigidity when rotating with said head member to cut vegetation at a substantially uniform height and which will permit deflection of said second portion sufficiently upon striking a rigid object in the path of said cutting pin offering greater resistance to movement than said vegetation to permit said end to pass by said object.