Low-profile grinding machine for sharpening lawn mower cutting reels

Abstract

One example provides a low-profile grinding machine for sharpening a cylindrical cutting reel of a mower unit. The grinding machine includes a grinding wheel driveable in a reciprocating fashion along a grinding axis, and a grinding platform. The grinding platform houses the grinding wheel and includes a bottom side to sit on a ground surface and an opposing upper side. The upper side includes a ramp portion sloping upwardly from the ground surface to enable the mower unit to be pushed or driven from the ground surface onto the upper surface to position the cylindrical cutting reel over the grinding wheel for sharpening, the lawn mower positioned with a rotational axis of the cylindrical cutting reel extending along the grinding axis.

What is claimed is: 
     
         1 . A low-profile grinding machine for sharpening a cylindrical cutting reel of a mower unit, the grinding machine comprising:
 a grinding wheel driveable in a reciprocating fashion along a grinding axis; and   a grinding platform housing the grinding wheel, the housing including:
 a bottom side to sit on a ground surface; and 
 an upper side including a ramp portion sloping upwardly from the ground surface to enable the mower unit to be pushed or driven from the ground surface onto the upper surface to position the cylindrical cutting reel over the grinding wheel for sharpening with a rotational axis of the cylindrical cutting reel extending along the grinding axis. 
   
     
     
         2 . The low-profile grinding machine of  claim 1 , wherein the mower unit comprises a walk-behind turf mower. 
     
     
         3 . The low-profile grinding machine of  claim 1 , wherein the mower unit comprises a cassette-type mower unit. 
     
     
         4 . The low-profile grinding machine of  claim 1 , wherein the grinding wheel and grinding axis are exposed to the upper side of the grinding platform. 
     
     
         5 . The low-profile grinding machine of  claim 1 , including a grinding wheel positioning system to adjust a position of the grinding axis to parallel the grinding wheel with a perimeter surface of the cylindrical cutting reel when the mower unit is positioned on the grinding machine. 
     
     
         6 . The low-profile grinding machine of  claim 5 , further including:
 a drive shaft driveable about a longitudinal axis of rotation, the grinding wheel coupled about a circumference of the drive shaft such that the longitudinal axis of rotation of the drive shaft is the grinding axis, the grinding wheel coupled about the drive shaft to be rotatable with the drive shaft and to be moveable laterally along the axis of rotation.   
     
     
         7 . The low-profile grinding machine of  claim 6 , the grinding wheel positioning system to adjust the position of the grinding axis by adjusting a position of the drive shaft, the grinding wheel positioning system comprising a pair of handwheels, each handwheel in mechanical communication with a corresponding one of the opposing lateral ends of the drive shaft, wherein each handwheel adjusts the vertical position of the corresponding one of the opposing ends of the drive shaft. 
     
     
         8 . The low-profile grinding machine of  claim 7 , wherein the grinding wheel is coupled to the drive shaft via a hub assembly, the hub assembly comprising:
 a tubular spin hub extending between a first end and a second end and defining an external circumferential surface and an internal circumferential surface, and including a key tab disposed on the internal circumferential surface, the grinding wheel fixedly coupled about the external circumferential surface between the first end and the second end;   a ring-shaped bearing assembly connected about the external circumferential surface at the second end of the spin hub;   a traverse arm having a circular bearing retainer disposed about a circular opening through the traverse arm, the bearing assembly retained within the bearing retainer so that the spin hub spins relative to the traverse arm.   
     
     
         9 . The low-profile grinding machine of  claim 8 , the external circumference surface of the spin hub being threaded at the first end, and the spin hub including a flange extending about the external circumferential surface between the first and second end, the hub assembly further including a nut to thread onto the first end and compress the grinding wheel between the nut and the flange to couple the grinding wheel to the spin hub. 
     
     
         10 . The low-profile grinding machine of  claim 8 , wherein the drive shaft includes a linear key slot extending laterally between the opposing lateral ends of the drive shaft, wherein the drive shaft extends through the circular opening of the traverse arm, through the ring-shaped bearing assembly, and through the spin hub with the key tab being slideably disposed within linear key slot such that the spin hub and grinding wheel spin with the drive shaft about the grinding axis, and move together with the traverse arm laterally along the grinding axis between the opposing lateral ends of the drive shaft. 
     
     
         11 . The low-profile grinding machine of  claim 10 , including a traverse drive system to drive the traverse arm laterally along the drive shaft. 
     
     
         12 . The low-profile grinding machine of  claim 11 , the traverse drive system including a drive belt coupled to the traverse arm which is controllably driven to move the traverse arm, together with the spin hub and grinding wheel, in a reciprocating fashion along the grinding axis. 
     
     
         13 . The low-profile grinding machine of  claim 1 , including a spin drive motor to connect to the rotational axis of the cylindrical cutting reel and controllable to spin the cylindrical cutting reel according to a plurality of selectable modes including a low-rpm, low-torque setup mode, and a high-rpm, high-torque grinding mode. 
     
     
         14 . The low-profile grinding machine of  claim 1 , further including:
 a stop disposed along the ramp portion, the stop operable between an extended position, where the stop is positioned to extend above an upper surface of the ramp portion, and a retracted position, where the stop is flush with or below the upper surface of the ramp portion.   
     
     
         15 . The low-profile grinding machine of  claim 14 , when the stop is in the extended position, the stop to pivot to the retracted position in response to a force being applied in an upward direction of the ramp portion and biased to return to the extended position in response to the force being removed. 
     
     
         16 . The low-profile grinding machine of  claim 14 , when a mower unit is disposed on the grinding platform for sharpening, the stop, when in the extended position, to engage a rear roller of the mower unit to prevent the mower unit from rolling down the ramp, the stop disposed at a location along the ramp portion between a bottom of the ramp portion and top of the ramp portion to position the cylindrical cutting reel over the grinding wheel for sharpening with a rotational axis of the cylindrical cutting reel extending along the grinding axis. 
     
     
         17 . The low-profile grinding machine of  claim 16 , wherein a location of the stop is adjustable along the ramp portion in a direction extending between a bottom of the ramp portion and a top of the ramp portion. 
     
     
         18 . A grinding machine for sharpening cylindrical cutting reels of lawn mowers, the grinding machine comprising:
 a grinding wheel;   a drive shaft extending longitudinally between opposing lateral ends, a longitudinal axis of rotation of the drive shaft representing a grinding axis; and   a hub assembly coupling the grinding wheel about the drive shaft, the hub assembly comprising:
 a tubular spin hub extending between a first end and a second end and defining an external circumferential surface and an internal circumferential surface, and including a key tab disposed on the internal circumferential surface, the grinding wheel fixedly coupled about the external circumferential surface between the first end and the second end; 
 a ring-shaped bearing assembly connected about the external circumferential surface at the second end of the spin hub; 
 a traverse arm having a circular bearing retainer disposed about a circular opening through the traverse arm, the bearing assembly retained within the bearing retainer so that the spin hub spins relative to the traverse arm. 
   
     
     
         19 . The grinding machine of  claim 18 , the external circumference surface of the spin hub being threaded at the first end, and the spin hub including a flange extending about the external circumferential surface between the first and second end, the hub assembly further including a nut to thread onto the first end and compress the grinding wheel between the nut and the flange to couple the grinding wheel to the spin hub. 
     
     
         20 . The grinding machine of  claim 18 , wherein the drive shaft includes a linear key slot extending laterally between the opposing lateral ends of the drive shaft, wherein the drive shaft extends through the circular opening of the traverse arm, through the ring-shaped bearing assembly, and through the spin hub with the key tab being slideably disposed within linear key slot such that the spin hub and grinding wheel spin with the drive shaft about the grinding axis, and move together with the traverse arm laterally along the grinding axis between the opposing lateral ends of the drive shaft. 
     
     
         21 . The grinding machine of  claim 20 , including a traverse drive system including a drive belt coupled to the traverse arm which is controllably driven to move the traverse arm, together with the spin hub and grinding wheel, in a reciprocating fashion along the drive shaft between the opposing first and second ends. 
     
     
         22 . A drive-on grinding machine for sharpening a cylindrical cutting reel of a lawn mower, the grinding machine comprising:
 a grinding platform having a bottom major surface to sit on a ground surface and an opposing upper major surface, the grinding platform housing a grinding wheel exposed from the upper major surface, the upper major surface including a ramp portion to facilitate the lawn mower to be pushed or driven from the ground surface onto the upper major surface to position the cylindrical cutting reel over the grinding wheel for sharpening.