Concrete finishing trowel with speed control

Abstract

A concrete finishing trowel includes a frame, a power source supported on the frame and having an output shaft, at least one rotor assembly supported on the frame. Each rotor assembly comprises a driven rotor shaft with a plurality of trowel blades extending outwardly therefrom so as to rest on a surface to be finished and to rotate with said driven rotor shaft to finish a respective circular area. A transmission system operably couples the power source output shaft to the driven rotor shaft of the at least one rotor assembly. The transmission system includes a variable driving pulley operable coupled directly or indirectly to the power source output shaft and including a resiliently deflectable portion that is movable to change the effective drive diameter of the variable driving pulley, and a variable driven pulley operably coupled to the variable driving pulley with a belt. The variable driven pulley in turn is operably coupled directly or indirectly to the driven rotor shaft of the at least one rotor assembly. A rotor speed control system permits an operator to adjust the center-to-center distance between the pulleys, thereby to cause the drive diameter of the variable driven pulley to change resulting in an adjustment of the speed of the driven rotor shaft.

1 . A concrete finishing trowel comprising:
 a frame;   a power source supported on the frame and having an output shaft;   at least one rotor assembly supported on the frame, each rotor assembly comprising a driven rotor shaft with a plurality of trowel blades extending outwardly therefrom so as to rest on a surface to be finished and to rotate with said driven rotor shaft to finish a respective circular area;   a transmission system operably coupling the power source output shaft to the driven rotor shaft of the at least one rotor assembly, comprising:
 a variable driving pulley operable coupled directly or indirectly to the power source output shaft and including a resiliently deflectable portion that is movable to change the effective drive diameter of the variable driving pulley; and 
 a variable driven pulley operably coupled to the variable driving pulley with a belt, and operably coupled directly or indirectly to the driven rotor shaft of the at least one rotor assembly; and 
   a rotor speed control system for permitting an operator to adjust the center-to-center distance between the pulleys,   wherein a change in the center-to-center distance causes the drive diameter of the variable driven pulley to change thereby to adjust the speed of the driven rotor shaft.   
     
     
         2 . The concrete finishing trowel as defined in  claim 1 , wherein said power source comprises an internal combustion engine. 
     
     
         3 . A concrete finishing trowel as defined in  claim 1 , wherein said transmission system further comprises a gearbox from which said driven rotor shaft extends and which tilts relative to said frame during a steering operation, said gearbox having an input shaft which is operatively coupled to said variable driven pulley via a U-joint drive shaft. 
     
     
         4 . A concrete finishing trowel as defined in  claim 1 , wherein each of the at least one rotor assembly further comprises a plurality of support arms which extend radially outwardly from said driven shaft and on which said trowel blades are mounted, and wherein said trowel blades are mountable on multiple axial locations on said support arms so as to alter the diameter of said circular area. 
     
     
         5 . A concrete finishing trowel as defined in  claim 4 , wherein said finishing trowel is a riding trowel comprising at least two rotor assemblies each for finishing a respective circular area. 
     
     
         6 . A finishing trowel as defined in  claim 5  and further comprising:
 a deck mounted on the frame; 
 an operator's pedestal positioned on said deck; and 
 an operator's seat supported by said pedestal; 
 wherein said pedestal and said seat are hingedly attached to said deck to permit access to components of said finishing trowel located thereunder. 
 
     
     
         7 . The concrete finishing trowel of  claim 1 , further comprising:
 a shear pin hub associated with the variable driven pulley, the shear pin hub adapted to receive a shear pin for mechanically coupling the at least one rotor assembly to the power source, wherein a shear pin is designed to break under predetermined conditions thereby to mechanically decouple the at least one rotor assembly from the power source with little damage.   
     
     
         8 . A concrete finishing trowel comprising:
 a frame;   a power source supported on the frame and having an output shaft;   at least one rotor assembly supported on the frame, each rotor assembly comprising a driven rotor shaft with a plurality of trowel blades extending outwardly therefrom so as to rest on a surface to be finished and to rotate with said driven rotor shaft to finish a respective circular area;   a transmission system operably coupling the power source output shaft to the driven rotor shaft of the at least one rotor assembly;   a steering system comprising a steering column operably coupled to the rotor assembly and operable to tilt the rotor driven shaft relative to the frame thereby to effect a steering operation, the steering system comprising a steering assistance subsystem operable to provide mechanical assistance to aid an operator when moving the steering column away from a neutral position.   
     
     
         9 . The concrete finishing trowel of  claim 8 , wherein the transmission system comprises:
 a variable driving pulley operable coupled directly or indirectly to the power source output shaft and including a resiliently deflectable portion that is movable to change the effective drive diameter of the variable driving pulley;   a variable driven pulley operably coupled to the variable driving pulley with a belt, and operably coupled directly or indirectly to the driven rotor shaft of the at least one rotor assembly;   the concrete finishing trowel further comprising:
 a rotor speed control system for permitting an operator to adjust the center-to-center distance between the pulleys, 
   wherein a change in the center-to-center distance causes the drive diameter of the variable driven pulley to change thereby to adjust the speed of the driven rotor shaft.