Bolt for attaching a rotary mower blade

1. A rotary mower apparatus comprising a rotating member defining a mounting aperture having a cross-section substantially corresponding to the cross-section of a shank of a blade bolt, the blade bolt comprising:

a head at a lower end;

a cylindrical shoulder portion extending from the head;

a shank extending from the shoulder portion, the shank having a cross-section that is rounded and non-cylindrical; and

a threaded portion extending from the shank;

wherein the shoulder portion extends laterally beyond at least a portion of the shank such that the shoulder portion bears against the rotating member when the shank is inserted into the mounting aperture;

wherein the shank extends into the mounting aperture such that the bolt is prevented from rotating in the mounting aperture.

2. A rotary mower apparatus comprising:

a rotary mower deck adapted for movement along the ground;

a blade pan rotatably mounted under the rotary mower deck, and a drive operative to rotate the pan about a substantially vertical pan axis;

a plurality of pan apertures defined about an outer portion of the pan, the pan apertures extending through the pan from a lower surface of the pan to an upper surface of the pan, the pan apertures having a cross-section that is rounded and non-cylindrical;

a plurality of mower blades, each blade pivotally attached to the pan by a blade bolt extending through a blade aperture defined by the blade, and upward through a pan aperture such that each blade is located adjacent to the lower surface of the pan;

wherein each blade bolt comprises:

a head on a lower end thereof;

a cylindrical shoulder portion extending upward from the head through the blade aperture of an attached blade such that a top end of the shoulder portion bears against the lower surface of the pan, and such that the attached blade can pivot on the shoulder portion under the pan;

a shank having a cross-section corresponding to the cross-section of the pan aperture such that the shank extends into the pan aperture and is prevented from rotating with respect to the pan aperture; and

a threaded portion extending from the shank;

a nut threaded to the threaded portion of each blade bolt such that the nut bears against the upper surface of the pan.

3. The apparatus of claim 2 wherein the cross-section of the shank aperture and shank is oblong.

4. The apparatus of claim 2 wherein the shank includes at least one rounded lobe extending laterally from a central portion thereof.

5. The apparatus of claim 4 comprising first and second rounded lobes extending laterally in opposite directions from the central portion of the shank.

6. The apparatus of claim 5 wherein the first and second lobes are configured such that cross-section of the shank is symmetrical.

7. The apparatus of claim 4 wherein the cross-section of the shank is substantially elliptical.