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A work machine includes a frame, at least one drive wheel carried by the frame, at least one caster wheel assembly carried by the frame, and at least one turn assist arrangement. Each turn assist arrangement is coupled between the frame and a corresponding caster wheel assembly. Each turn assist arr

A work machine includes a frame, at least one drive wheel carried by the frame, at least one caster wheel assembly carried by the frame, and at least one turn assist arrangement. Each turn assist arrangement is coupled between the frame and a corresponding caster wheel assembly. Each turn assist arrangement is configured to bias the corresponding caster wheel assembly during an operator commanded turn, and to be overridden by forces applied by the ground to the caster wheel assembly.

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1. A work machine, comprising: a frame;at least one drive wheel carried by said frame;at least one caster wheel assembly carried by said frame by way of a pivotable shaft that defines a generally vertical pivot axis around which the caster wheel assembly can rotate 360 degrees; andat least one turn

1. A work machine, comprising: a frame;at least one drive wheel carried by said frame;at least one caster wheel assembly carried by said frame by way of a pivotable shaft that defines a generally vertical pivot axis around which the caster wheel assembly can rotate 360 degrees; andat least one turn assist arrangement, each said turn assist arrangement coupled between said frame and a corresponding said caster wheel assembly, each said turn assist arrangement being fluidly coupled with a hydraulic steering circuit of the work machine whereby a pressure differential exists in the turn assist arrangement during a turning of the work machine, the pressure differential causing a turn assist force to be applied to bias said corresponding caster wheel assembly during an operator commanded turn and to be overridden by forces applied by the ground to said caster wheel assembly. 2. The work machine of claim 1, wherein each said turn assist arrangement comprises one of a linear actuator and a rotary actuator. 3. The work machine of claim 1, wherein said at least one turn assist arrangement includes at least one turn assist cylinder, each said turn assist cylinder coupled between said frame and a corresponding said caster wheel assembly, each said turn assist cylinder including a two-way cylinder with a housing defining an inner chamber, a piston slidably disposed in said inner chamber, and a rod extending from said piston through said housing, said inner chamber on each side of said piston being fluidly coupled with the hydraulic steering circuit whereby a pressure differential on opposite sides of said piston exists during turning of said work machine. 4. The work machine of claim 3, wherein each said caster wheel assembly includes a pivotable shaft, a wheel arm and a caster wheel coupled with said wheel arm, each said housing connected to one of said frame and said corresponding shaft, each said rod connected to an other of said frame and said corresponding shaft. 5. The work machine of claim 4, wherein each said caster wheel assembly includes a pivot arm having one end which is coupled with and extends radially from said shaft, and an opposite end which is coupled with a corresponding said turn assist cylinder. 6. The work machine of claim 4, wherein said housing is connected to said frame, and said rod is connected to said corresponding caster wheel assembly. 7. The work machine of claim 3, wherein said at least one drive wheel comprises a pair of drive wheels, and said hydraulic steering circuit is one of: integral with a dual-path hydrostatic system associated with said drive wheels; anda stand-alone hydraulic circuit which is separate from said dual-path hydrostatic system. 8. The work machine of claim 3, wherein said at least one drive wheel includes two drive wheels and two hydraulic drive wheel motors respectively associated with said drive wheels, each said drive wheel motor having an inlet, each said inlet being fluidly coupled with each said turn assist cylinder, such that an inlet of one said drive wheel motor is fluidly coupled with said inner chamber on one side of said piston and an inlet of an other said drive wheel motor is fluidly coupled with said inner chamber on an opposite side of said piston. 9. The work machine of claim 3, wherein said at least one turn assist cylinder comprises two turn assist cylinders, each said turn assist cylinder coupled between said frame and a corresponding said caster wheel assembly. 10. The work machine of claim 9, including a pair of low speed field orifices, each said field orifice being fluidly connected in parallel with a corresponding said turn assist cylinder on opposite sides of said corresponding piston, each said field orifice being open at a ground speed at or below a first threshold value. 11. The work machine of claim 9, including a pair of higher speed transport orifices, each said transport orifice being fluidly connected in parallel with a corresponding said turn assist cylinder on opposite sides of said corresponding piston. 12. The work machine of claim 9, including a pair of high pressure relief valves, each said high pressure relief valve being fluidly connected in parallel with a corresponding said turn assist cylinder on opposite sides of said corresponding piston, each said high pressure relief valve being openable above a predetermined a fluid pressure. 13. The work machine of claim 9, including a pair of machine direction change valves, each said machine direction change valve being fluidly connected in parallel with a corresponding said turn assist cylinder on opposite sides of said corresponding piston, each said machine direction change valve being open during an operator commanded change in direction of said work machine. 14. The work machine of claim 9, including a proportional valve connected in parallel between said two turn assist cylinders, said proportional valve being open below a ground speed at a first threshold value, beginning to close when said ground speed is at said first threshold value, and closed when said ground speed is at a second threshold value, said proportional valve closing linearly proportional to an increase in ground speed between said first threshold value and said second threshold value. 15. The work machine of claim 3, wherein said at least one caster wheel assembly is a pair of caster wheel assemblies, and said at least one turn assist cylinder comprises one of: a pair of turn assist cylinders, each said turn assist cylinder coupled between said frame and a corresponding said caster wheel assembly;a single turn assist cylinder coupled between said frame and one said caster wheel assembly; anda single turn assist cylinder coupled between said frame and one said caster wheel assembly, said one caster wheel assembly coupled via a tie rod with an other said caster wheel assembly. 16. The work machine of claim 3, wherein each said turn assist cylinder includes a second rod extending from said piston through said housing, said rod and said second rod being disposed on opposite sides of said piston, said second rod providing an equal fluid displacement from said inner chamber regardless of a travel direction of said piston. 17. A steering arrangement for a work machine, comprising: a frame;a caster wheel assembly carried by said frame; anda turn assist arrangement coupled between said frame and said caster wheel assembly, said turn assist arrangement being fluidly coupled with a hydraulic steering circuit of the work machine whereby a pressure differential exists in the turn assist arrangement during a turning of the work machine, the pressure differential causing a turn assist force to be applied to: a) apply a biasing force to said caster wheel assembly during an operator commanded turn,b) allow said biasing force to be overridden by forces applied by the ground to said caster wheel assembly, andc) allow said caster wheel assembly to rotate 360° about a generally vertical axis. 18. The steering arrangement of claim 17, wherein said caster wheel assembly includes a pivotable shaft coupled with a wheel arm, a caster wheel coupled with said wheel arm, and a pivot arm having one end which is coupled with and extends radially from said shaft, and an opposite end which is coupled with said turn assist arrangement. 19. The steering arrangement of claim 17, wherein said turn assist arrangement includes a turn assist cylinder with a housing defining an inner chamber, a piston slidably disposed in said chamber, and a rod extending from said piston through said housing, and further including: a low speed field orifice fluidly connected in parallel with said turn assist cylinder on opposite sides of said piston, said field orifice being open at a ground speed at or below a first threshold value; anda higher speed transport orifice fluidly connected in parallel with said turn assist cylinder on opposite sides of said piston. 20. The steering arrangement of claim 19, wherein each said turn assist cylinder includes a second rod extending from said piston through said housing, said rod and said second rod being disposed on opposite sides of said piston, said second rod providing an equal fluid displacement from said inner chamber regardless of a travel direction of said piston. 21. A work machine, comprising: a frame;at least one caster wheel assembly carried by said frame, each said caster wheel assembly including a caster wheel and a pivotable shaft defining a generally vertical axis; andat least one turn assist arrangement, each said turn assist arrangement being coupled between said frame and a corresponding said caster wheel assembly, each said turn assist arrangement fluidly coupled with a hydraulic steering circuit of the work machine whereby a pressure differential exists in the turn assist arrangement during a turning of the work machine, the pressure differential causing a turn assist force to be applied biasing said corresponding caster wheel during an operator commanded turn and allowing said caster wheel to rotate 360° about said axis of said shaft. 22. The work machine of claim 21, wherein each said turn assist arrangement comprises one of a linear actuator and a rotary actuator. 23. The work machine of claim 22, wherein each said turn assist arrangement includes at least one of: a) at least one fluid orifice;b) at least one clutch; andc) at least one brake. 24. The work machine of claim 21, wherein said biasing applied to said corresponding caster wheel assembly during an operator commanded turn may be overrode by forces applied by the ground to said caster wheel. 25. The work machine of claim 21, wherein each said caster wheel assembly includes a pivot arm having one end which is coupled with and extends radially from said shaft, and an opposite end which is coupled with a corresponding said turn assist arrangement.