Cordless electric grass shear having improved blade system

A battery powered grass shear having improved cutting and durability characteristics and lower battery drain comprising:

• a housing;
• battery means carried by said housing;
• motor means mounted within said housing and selectively interconnectable with said battery means whereby said motor means may be selectively operated, said motor means including output means;
• drive means mounted within said housing and interconnected with the output means of said motor means;
• a lower shear blade of comparatively thick hardenable steel, said lower shear blade having a generally horizontal trailing portion, a first intermediate portion, aperture means disposed between the first intermediate portion and the trailing portion and lying substantially midway between the sides of the first intermediate and trailing portions, said first intermediate portion and said trailing portion substantially lying in a common plane, an upwardly and forwardly extending second intermediate portion, and a plurality of transversely spaced apart V-shaped upwardly and forwardly extending cutting teeth interconnected with said second intermediate portion, said V-shaped cutting teeth and said second intermediate portion substantially lying in a common plane disposed at an angle to the plane of the trailing portion and the first intermediate portion;
• means rigidly securing the trailing portion of said lower shear blade to said housing;
• an upper movable shear blade of hard, relatively thin, heat hardenable resilient steel, said upper shear blade having a trailing portion, a forward portion provided with a plurality of transversely spaced apart V-shaped forwardly extending cutting teeth, aperture means lying between the forward and trailing portions and midway between the sides of the trailing and forward portions, said trailing and forward portions lying in substantially the same plane when in a free, non-stressed state, said trailing portion of said upper movable shear blade being interconnected with said drive means in such a manner that when said motor means is selectively interconnected with said battery means said trailing portion will be reciprocated from side to side relative to the trailing portion of said lower shear blade;
• bearing means disposed between the trailing portions of said upper and lower shear blades and adapted to maintain the facing surfaces of the trailing portions in spaced apart relationship with respect to each other;
• and
• pivot means extending between the said apertures in said upper and lower shear blades, said pivot means having upper abutment means adapted to contact the upper surface of said upper shear blade to keep said upper blade from moving away from the lower shear blade beyond a prescribed amount, the plane defined by the lower trailing surface of the upper blade when in contact with the bearing means and the upper abutment mans of said pivot means intersecting the upper surface of the second intermediate portion of said lower shear blade;
• the parts being so arranged and constructed that when in their assembled relationship the cutting edges of the cutting teeth of the upper blade will be spring loaded into point to point contact against the cutting edges of cutting teeth of the lower blade due to the upper blade being resiliently stressed out of its free state, the teeth of the upper and lower blades maintaining only point to point contact with each other along their intersecting cutting edges during reciprocation of upper shear blade.

A battery powered grass shear having improved cutting and durability characteristics and lower battery drain comprising:

• a housing:
• battery means carried by said housing;
• motor means mounted within said housing and selectively interconnectable with battery means whereby said motor means may be selectively operated, said motor means including output means;
• drive means mounted within said housing and interconnected with the output means of said motor means;
• a kinked lower shear blade of comparatively thick steel, said lower blade having a trailing portion securable to said housing, a first intermediate portion, aperture means disposed between the first intermediate portion and the trailing portion and lying substantially midway between the sides of the intermediate and trailing portions, said first intermediate portion and said trailing portion lying in substantially a common plane, a second upwardly and forwardly extending intermediate portion, and a plurality of spaced apart V-shaped forwardly extending cutting teeth interconnected with second intermediate portion, said V-shaped teeth having cutting edges hardened to at least 56 on the Rockwell C Scale, and said V-shaped cutting teeth and said second intermediate portion lying in substantially a common plane disposed at an angle of 2.degree. to 5.degree. relative to an extension of the plane of the trailing portion and the first intermediate portion;
• means rigidly securing the trailing portion of said lower shear blade to said housing:
• an upper shear blade of hard, relatively thin, resilient steel, said upper shear blade having a trailing portion, a forward portion provided with a plurality of transversely disposed V-shaped cutting teeth, said V-shaped teeth having cutting edges of substantially the same hardness as the cutting edges of the cutting teeth of the lower shear blade, aperture means lying between the forward and trailing portions and midway between the sides of the forward and trailing portions, said trailing and forward portions lying substantially the same plane when the upper shear blade is in a free, non-stressed state, and said trailing portions of said upper shear blade being interconnected with said drive means in such a manner that when said motor means is selectively interconnected with said battery means said trailing portion will be reciprocated from side to side relative to the trailing portion of said lower shear blade;
• and
• means cooperable with the kinked lower shear blade and the upper shear blade to orient the upper blade relative to the lower blade to maintain only point to point contact between the intersecting cutting edges of the upper and lower cutting teeth of said shear blades during reciprocating of the upper shear blade and also to sufficiently spring load the upper blade to insure sufficient point contact pressure between the intersecting cutting edges of the cutting teeth of the upper and lower shear blades to prevent inadvertent separation of the upper and lower cutting teeth during normal operation thereof, said means including
• pivot means passing through the apertures in said upper and lower shear blades, said pivot means having upper abutment means adapted to contact the upper surface of the upper movable shear blade thereby permitting the upper blade at the point of pivotal interconnection to be spaced away from the lower blade only a limited amount, and
• bearing means disposed between the trailing portion of the upper shear blade and the trailing portion of the lower shear blade, said bearing means maintaining the facing surface of the trailing portions of the upper and lower blades in spaced apart relationship with respect to each other;
• the plane defined by the lower trailing surface of the upper blade when in contact with the bearing means and the upper abutment means of said pivot means intersecting the upper surface of the second intermediate portion of said kinked lower shear blade;
• the parts being so arranged and constructed that when the rearward ends of the cutting surfaces are in point to point contact, the leading portion of the upper shear blade will be flexed upwardly out of said last mentioned plane a small amount, and when the forward end of the cutting surfaces are in point to point contact the leading portion of the upper shear blade will be flexed upwardly out of said last mentioned plane a greater amount.