초록 ▼

Disclosed are horsepower management systems and methods for use on power machines with an engine that powers a drive system. An engine speed control device controls the engine speed. A variable displacement drive pump controlled by a displacement control member provides pressurized fluid to a drive

Disclosed are horsepower management systems and methods for use on power machines with an engine that powers a drive system. An engine speed control device controls the engine speed. A variable displacement drive pump controlled by a displacement control member provides pressurized fluid to a drive motor. A control system communicates with the engine speed control device and the pump displacement control member. The control system includes a user input device and a command lever rotatably coupled to the displacement control member and capable of receiving the user input. The command lever provides a signal to the engine speed control device in response to the user input. The command lever also commands a given displacement via the displacement control member subject to load forces on the hydrostatic pump transmitted to a limiting mechanism coupled to the command lever and the displacement control member.

대표청구항 ▼

1. A power machine having an engine and a drive system powered by the engine, comprising: an engine speed control device coupled to the engine and configured to control engine speed;a variable displacement drive pump driven by the engine and having a displacement control member for controlling displ

1. A power machine having an engine and a drive system powered by the engine, comprising: an engine speed control device coupled to the engine and configured to control engine speed;a variable displacement drive pump driven by the engine and having a displacement control member for controlling displacement of the drive pump;a drive motor that receives pressurized fluid from the drive pump; anda control system configured to communicate with the engine speed control device and the displacement control member, including: a user input device capable of providing a user input signal;a command lever rotatably coupled to the displacement control member and capable of receiving the user input, wherein the command lever provides an engine speed command signal to the engine speed control device in response to the user input;a limiting mechanism coupled to the command lever and the displacement control member;wherein the command lever commands a given displacement of the drive pump via the displacement control member in response to actuation of the user input subject to load forces on the drive pump transmitted to the limiting mechanism via the displacement control member. 2. The power machine of claim 1, wherein the command lever, displacement control member, and limiting mechanism are configured such that when load forces from the drive pump reach a given level, the limiting mechanism allows movement of the displacement control member relative to the command lever to reduce pump displacement in response to the load forces above the given level. 3. The power machine of claim 1, wherein the user input device is a foot pedal positioned in an operator compartment of the power machine. 4. The power machine of claim 1, wherein the command lever is coupled to the engine speed control device through first and second cables connected to first and second ends of the command lever, respectively. 5. The power machine of claim 1, wherein the user input device is mechanically coupled to the command lever. 6. The power machine of claim 1, wherein the limiting mechanism comprises a spring. 7. The power machine of claim 6, wherein the limiting mechanism comprises a torsional spring. 8. The power machine of claim 6, wherein the limiting mechanism is selected from one of an extension spring and a compression spring. 9. The power machine of claim 2, and further comprising a stop positioned to limit a reduction in the displacement of the drive pump via the limiting mechanism. 10. The power machine of claim 9, wherein the stop comprises one of a tab and a slot form on the displacement control member and the other of a tab and a slot formed on the command lever, wherein the tab engages the slot to limit movement of the displacement control member relative to the command lever via the limiting mechanism. 11. The power machine of claim 2, wherein when load forces from the drive pump reach the given level, the engine speed command signal is not reduced by the limiting mechanism. 12. A control system for controlling an engine and a hydrostatic pump of a power machine, a rotational speed of the engine being controlled by an engine speed control device in response to a user input, and displacement of the hydrostatic pump being controlled by a position of a swash plate actuated by a rotatable actuator, the control system comprising: a command lever rotatably coupled to the rotatable actuator and coupled to the user input and to the engine speed control device such that movement of the user input causes rotational movement of the command lever about the rotational actuator, the rotational movement of the command lever being transmitted to the engine speed control device to control the engine speed;a pintle lever fixed to the rotatable actuator such that rotation of the pintle lever controls the position of the swash plate; anda spring mechanism coupling the command lever to the pintle lever such that when the command lever is rotated by movement of the user input, the pintle lever is rotated to change the displacement of the hydrostatic pump subject to load forces on the hydrostatic pump transmitted to the spring mechanism that limit rotation of the pintle lever in response to rotation of the command lever. 13. The control system of claim 12, wherein the command lever, pintle lever and spring mechanism are configured such that when load forces from the hydrostatic pump surpass a given level, the spring mechanism allows movement of the pintle lever relative to the command lever to reduce the displacement of the hydrostatic pump when the load forces remain above the given level. 14. The control system of claim 12, wherein the command lever is coupled to the engine speed control device through first and second cables connected to first and second ends of the command lever, respectively. 15. The control system of claim 12, wherein the command lever is mechanically coupled to the user input device. 16. The control system of claim 12, wherein the spring mechanism comprises a torsional spring. 17. The control system of claim 12, wherein the spring mechanism comprises one of an extension and a compression spring. 18. The control system of claim 13, and further comprising: a stop positioned to limit movement of the pintle lever relative to the command lever in response to load forces transmitted to the spring mechanism. 19. The control system of claim 18, wherein the stop comprises a tab on one of the pintle lever and the command lever and a slot formed in the other of the pintle lever and the command lever, and wherein the tab engages the slot to prevent further movement of the pintle lever relative to the command lever. 20. The control system of claim 12, wherein the transmission of rotational movement from the command lever to the engine speed control device is unaffected by the spring mechanism.