System for controlling a power output

1. A system for controlling power output comprising:

a first hydraulic actuator configured to output a first torque to a geared transmission;

a source of pressurized fluid configured to supply a first flow of pressurized fluid to the first hydraulic actuator;

a second actuator configured to receive a second flow of pressurized fluid;

a first sensor configured to sense the first torque;

a second sensor configured to sense a first pressure of the first flow of pressurized fluid; and

a controller configured to selectively vary the first flow of pressurized fluid as a function of the movement of the second actuator in response to the sensed first torque, a predetermined torque, and the sensed first pressure.

2. The system of claim 1 , wherein the source of pressurized fluid is a variable displacement pump and the controller is configured to adjust a displacement of the pump to vary the first torque.

3. The system of claim 1 , wherein the controller is configured to control the first flow of pressurized fluid to establish the first torque to be substantially equal to the predetermined torque.

4. The system of claim 3 , wherein the predetermined torque is a desired torque corresponding to a first signal indicative of a position of an operator interface device.

5. The system of claim 4 , further including: the first sensor configured to communicate a second signal, indicative of the first torque, to the controller;

wherein the controller is further configured to compare the first signal with the second signal.

6. The system of claim 1 , further including a power source configured to output a second torque to the source of pressurized fluid and output a third torque to the geared transmission.

7. The system of claim 1 , wherein:

the source of pressurized fluid is a variable displacement pump having a swashplate configured to adjust the flow of pressurized fluid as a function of an angle of the swashplate;

the second actuator includes a piston movable relative to a cylinder; and

movement of the piston relative to the cylinder changes the angle of the swashplate.

8. The system of claim 1 , wherein the second actuator includes a cylinder and a piston movable relative to the cylinder and the controller is further configured to determine a pressure differential across the piston, the pressure differential configured to affect control of the flow of pressurized fluid.

9. A method for controlling a power output comprising:

supplying a first flow of pressurized fluid to a first hydraulic actuator and generating a first torque, the first torque selectively changing as a function of a load operatively connected to the hydraulic actuator via a geared transmission;

selectively supplying a second flow of pressurized fluid to a second actuator;

selectively varying the first flow of pressurized fluid as a function of the movement of the second actuator;

sensing the first torque;

sensing a first pressure of the first flow of pressurized fluid; and

selectively moving the second actuator as a function of the sensed first torque and first pressure.

10. The method of claim 9 , further including:

generating a second torque;

supplying a first portion of the second torque to a source of pressurized fluid; supplying a second portion of the second torque to the geared transmission; and

supplying the first torque to the transmission;

wherein the transmission is configured to supply a third torque to the load, the load operatively connected to the geared transmission.

11. The method of claim 10 , wherein the source of pressurized fluid is configured to supply the first flow of pressurized fluid to the hydraulic actuator.

12. The method of claim 10 , wherein the load operatively connected to the transmission changes.

13. The method of claim 10 , wherein the geared transmission operatively combines the first and second torques to establish the third torque, the third torque being continuously variable at least within a predetermined range of torques.

14. A transmission system comprising:

a power source configured to produce a torque and a speed;

a first transmission device operatively connected to the power source and configured to output a first power output to a load;

a second transmission device operatively connected to the power source and the first transmission device, the second transmission device configured to output a second power output to the first transmission device as a function of a first flow of pressurized fluid;

an actuator configured to selectively receive a second flow of pressurized fluid;

a sensor configured to sense the second power output;

a sensor configured to sense the pressure of the first flow of pressurized fluid; and

a controller configured to selectively move the actuator as a function of the sensed first torgue and first pressure to vary the second power output.

15. The transmission of claim 14 , wherein the second power output changes in response to changes in the load.

16. The transmission of claim 14 , wherein the second transmission device includes:

a hydraulic motor configured to produce the second power output; and

a variable displacement pump configured to supply the first flow of pressurized fluid to the hydraulic motor.

17. The transmission of claim 14 , wherein the actuator includes first and second chambers separated by a piston, the transmission further including:

a valve configured to selectively communicate pressurized fluid to and from the first and second chambers to affect movement of the piston wherein movement of the piston varies the first flow of pressurized fluid.