Dual-path, single-pump hydrostatic drive for mower

Abstract

A turf care machine includes a base mounted on a plurality of wheels, a support structure affixed to and extending from the base for supporting a turf machine operator interface, and a hydraulic control system for regulating the speed and direction of the mower. The hydraulic system includes: an engine with a drive shaft; a single hydraulic pump driven by the engine; a first valve set having an inlet connected to the pump outlet; a first hydraulic wheel motor connected to the first valve set; a second valve set connected to the first valve set and to second hydraulic wheel motor. This drive system has the advantage of using only one pump for driving both drive wheels in a seemingly independent dual path mode of operation, thereby minimizing cost and the number of fluid linkages and parts in such a system.

What is claimed is:  
     
         1 . In a turf machine including a base mounted on a plurality of wheels and having a turf machine operator interface, a hydraulic control system for regulating the speed and direction of the turf machine, comprising: 
 an engine;    a hydraulic pump, driven by the engine, having an inlet and an outlet providing a source of unidirectional pressurized hydraulic fluid useful for driving hydraulic motors;    a first valve set having an inlet connected to the hydraulic pump outlet and a first and second outlet;    a first hydraulic motor having an inlet connected to the first outlet of the first valve set and an outlet;    a second valve set having an inlet connected to the second outlet of the first valve set, further having a first and second outlet, the second outlet being connected to the inlet of the hydraulic pump; and    a second hydraulic motor having an inlet connected to the first outlet of the second valve set, wherein the first and second hydraulic motors are coupled to the hydraulic pump in series.    
     
     
         2 . The system of  claim 1 , wherein said first valve set contains a first variable volume control valve which regulates volume and direction of fluid flow to the first hydraulic motor; and 
 wherein the second valve set contains a second variable volume control valve which regulates volume and direction of the fluid flow to the second hydraulic motor.    
     
     
         3 . The system of  claim 1 , wherein the pump is a variable volume pump.  
     
     
         4 . The system of  claim 2 , wherein the first variable volume control valve contains a first forward setting for driving the first hydraulic motor in a forward direction, a neutral position for not allowing fluid to flow to the first hydraulic motor, a reverse setting for providing flow for driving the first hydraulic motor in a reverse direction and; 
 a second variable volume control valve contains a first forward setting for driving the second hydraulic motor in a forward direction, a neutral position for not allowing fluid to flow to the second hydraulic motor, a reverse setting for providing a flow for driving the second hydraulic motor in a reverse direction.    
     
     
         5 . The system of  claim 4 , further having a left operable control coupled to the first valve; 
 a first operable control coupled to the second valve; and    a second operable control coupled to the hydraulic pump.    
     
     
         6 . The system of  claim 3  having a first clutch disposed between the engine and the hydraulic pump.  
     
     
         7 . In a turf machine including a base mounted on a plurality of wheels, a hydraulic control system for regulating the speed and direction of the mower comprising: 
 a hydraulic pump, having an outlet and an inlet, for controlling hydraulic fluid flow;    a first valve set having a first and second inlet connected to the hydraulic pump outlet and a first and second outlet;    a first hydraulic motor having an inlet connected to the first outlet of the first valve set and an outlet connected to the second inlet of the first valve set;    a second valve set having a first and second inlet, the first inlet being connected to the second outlet of the first valve set, and further having a first and second outlet, the second outlet being connected to the inlet of the hydraulic pump;    a second hydraulic motor having an inlet connected to the first outlet of the second valve set and an outlet connected to the second inlet of the second valve set, wherein the first and second hydraulic motors are coupled to the hydraulic pump in series.    
     
     
         8 . The system of  claim 7 , wherein said first valve set contains a first variable volume control valve which regulates volume and direction of fluid flow to the first hydraulic motor; and 
 wherein the second valve set contains a second variable volume control valve which regulates volume and direction of the fluid flow to the second hydraulic motor.    
     
     
         9 . The system of  claim 7 , wherein the pump is a single direction variable volume pump.  
     
     
         10 . The system of  claim 9 , wherein the first variable control valve contains a first forward setting for driving the first hydraulic motor in a forward direction, a neutral position for not allowing fluid to flow to the first hydraulic motor, a reverse setting for providing flow for driving the first hydraulic motor in a reverse direction and; 
 a second variable control valve contains a first forward setting for driving the second hydraulic motor in a forward direction, a neutral position for not allowing fluid to flow to the second hydraulic motor, a reverse setting for providing a flow for driving the second hydraulic motor in a reverse direction.    
     
     
         11 . The system of  claim 9  having a first clutch disposed between the internal combustion engine and the variable volume pump.  
     
     
         12 . The system of  claim 11  further having cutter blades and a second clutch disposed between the engine and the cutter blades.