1. A mower blade, comprising:
a mid-section;
two sharpened end sections on opposite sides of said mid-section to define an elongated portion; and
a blade longitudinal axis extending through said mid-section and said end sections, said mid-section including a circular central hole having a diameter and being centered on said blade longitudinal axis, and first and second slots centered on said blade longitudinal axis, each of said first and second slots being positioned on opposite sides of said central hole, each of said first and second slots extending parallel said blade longitudinal axis and having a width that is transverse to, and crosses said blade longitudinal axis,
said mid-section also including first and second circular side holes spaced apart from the circular central hole, the first and second circular side holes positioned off said blade longitudinal axis and on opposite sides of said central hole, each of said first and second side holes and said central hole being centered on a common axis that is oblique to said blade longitudinal axis.
2. A mower blade according to claim 1, wherein said end sections include respective outer segments and inner segments, said outer segments of said end sections are twisted in opposite directions with respect to one another about said blade longitudinal axis, and said inner segments of said end sections are twisted in opposite directions with respect to one another about said blade longitudinal axis.
3. A mower blade according to claim 1, wherein each of said first and second side holes have a diameter that is smaller than said diameter of said central hole.
4. A mower blade according to claim 1, wherein said diameter of said central hole is larger than said width of each of said first and second slots.
5. A mower blade assembly, comprising:
a mower blade positioned on an adapter, said mower blade having a mid-section, two sharpened end sections on opposite sides of said mid-section, and a blade longitudinal axis extending through said mid-section and said end sections,
said mid-section including a circular central hole having a diameter and being centered on said blade longitudinal axis, and first and second slots centered on said blade longitudinal axis, each of said first and second slots being positioned on opposite sides of said central hole,
said mid-section also including first and second circular side holes spaced apart from the circular central hole, the first and second circular side holes positioned off said blade longitudinal axis and on opposite sides of said central hole, each of said first and second side holes and said central hole being centered on a common axis that is oblique to said blade longitudinal axis, and
said adapter attached to a lawnmower, said adapter having a central protrusion protruding from a bottom side of said adapter, said central protrusion having a plurality of teeth projecting from an outer circumference of said central protrusion and having an outermost diameter that is smaller than said diameter of said central hole, and said central protrusion being positioned completely within said central hole.
6. A mower blade assembly according to claim 5, wherein said end sections include respective outer segments and inner segments, said outer segments of said end sections are twisted in opposite directions with respect to one another about said blade longitudinal axis, and said inner segments of said end sections are twisted in opposite directions with respect to one another about said blade longitudinal axis.
7. A mower blade assembly according to claim 5, wherein said adapter also includes first and second extensions on opposite sides of said central protrusion and projecting from said bottom side of said adapter, and said first and second extensions being positioned completely within respective first and second circular, side holes in said mower blade.
8. A mower blade assembly according to claim 5, wherein said central protrusion has four teeth.
9. A mower blade assembly according to claim 5, further comprising: a blade mounting device that secures said mower blade on said adapter.
10. A mower blade assembly according to claim 9, wherein said blade mounting device includes a blade support and a fastener.
11. A mower blade assembly according to claim 10, wherein said blade support has a pair of extensions that are positioned within said first and second circular side holes.
12. A mower blade assembly according to claim 9, further comprising:
a washer positioned between said blade mounting device and said mower blade.
13. A mower blade assembly, comprising:
a mower blade positioned on an adapter, said mower blade having a mid-section, two sharpened end sections on opposite sides of said mid-section, and a blade longitudinal axis extending through said mid-section and said end sections,
said mid-section including a circular central hole having a diameter and being centered on said blade longitudinal axis, and first and second slots centered on said blade longitudinal axis, each of said first and second slots being positioned on opposite sides of said central hole, each of said first and second slots extending along said blade longitudinal axis and having a width that is transverse to said blade longitudinal axis and that is established at a maximum extent of said width by a pair of opposite, substantially parallel sides that are substantially parallel to said blade longitudinal axis,
said mid-section also including first and second circular side holes spaced apart from the circular central hole, the first and second circular side holes positioned off said blade longitudinal axis and on opposite sides of said central hole, each of said first and second side holes and said central hole being centered on a common axis that is oblique to said blade longitudinal axis, and
said adapter attached to a lawnmower, said adapter having a central protrusion protruding from a bottom side of said adapter, said central protrusion having an outermost diameter that is smaller than said diameter of said central hole, and said central protrusion being positioned completely within said central hole.
14. A mower blade assembly according to claim 13, wherein said adapter also has first and second side pins on opposite sides of said central protrusion protruding from said bottom side of said adapter, and said first and second side pins being positioned completely within respective first and second slots of said mower blade.
15. A mower blade assembly according to claim 13, wherein said end sections include respective outer segments and inner segments, said outer segments of said end sections are twisted in opposite directions with respect to one another about said blade longitudinal axis, and said inner segments of said end sections are twisted in opposite directions with respect to one another about said blade longitudinal axis.
16. A mower blade assembly according to claim 13, wherein said adapter also includes first and second extensions on opposite sides of said central protrusion projecting from said bottom side of said adapter, and said first and second extensions being positioned completely within respective first and second circular side holes in said mower blade.
17. A mower blade assembly according to claim 13, further comprising:
a blade mounting device that secures said mower blade on said adapter.
18. A mower blade assembly according to claim 17, wherein said blade mounting device includes a blade support and a fastener.
19. A mower blade assembly according to claim 18, wherein said blade support has a pair of protrusions that are positioned within said first and second circular side holes.
20. A mower blade assembly according to claim 17, further comprising:
a washer positioned between said blade mounting device and said mower blade.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An umbrella comprising:
a shaft having upper and lower ends and defining an axis;
a head piece at the upper end;
a slide piece between the upper and lower ends, one of the pieces having an upper part and a lower part made of ultrasonically weldable plastic and respectively having generally planar upper and lower faces that are engaged together and that are each formed with an array of axially open generally semispherical seat halves, the seat halves of the upper part forming with the seat halves of the lower part a plurality of seats of predetermined diameter spaced angularly about the shaft, the parts being formed at each seat with a radially outwardly open and axially extending notch of an angular width substantially smaller than the diameter of the respective seat, the face of one of the parts being formed with axially extending centering pins and the face of the other of the parts being formed with axially open holes receiving the pins;
an ultrasonic weld fixing the parts together at the faces;
a frame having a set of rib elements with inner ends engaged in the head piece and a set of strut elements having inner ends engaged in the slide piece and outer ends engaged with the rib elements, the elements of the set engaged in the one piece each having a shaft of a width at most equal to the notch width and a head of a diameter smaller than the seat diameter, the heads being received in the seats and the shafts projecting outward from the respective seats through the respective notches; and
a canopy fitted over the ribs elements outside the head piece.
2. The umbrella defined in claim 1 wherein the heads and seats are substantially complementarily spherical.
3. The umbrella defined in claim 1 wherein each of the parts is generally cylindrical and coaxial with the shaft.
4. The umbrella defined in claim 3 wherein the faces of the parts are generally perpendicular to the axis, the seats being generally semispherical and open axially.