Utility Vehicle Having Adaptive Drive Limiting Control

A utility vehicle comprising:

• a. a chassis;
• b. at least first and second laterally-spaced driven ground supports that support the chassis on the ground, each ground support comprising at least one of a wheel and a track;
• c. an engine that is supported on the chassis;
• d. first and second hydraulic drive motors, each of which is supported on the chassis, is operatively coupled to the engine, and is operatively coupled to a respective one of the first and second ground supports, the drive motors being configured to drive the ground supports to propel the vehicle over the ground and to steer the vehicle;
• e. an electronic over hydraulic control system including
• i. an electronic controller;
• ii. a pump assembly that is fluid communication with the first and second hydraulic drive motors, the pump assembly including a pump output control device that is in electronic communication with the electronic controller and that can be actuated to adjust pump output;
• and
• iii. first and second manually-actuated joysticks which are configured to control operation of the first and second drive motors, wherein the electronic controller is configured to
• 1. receive drive command signals from the joysticks, and
• 2. transmit drive signals to the pump output control devices in dependence on the received drive command signals, wherein
• the electronic controller is configured to receive drive command signals from the joysticks, then scale the drive command signals to generate pump output control signals that are calculated to propel the vehicle at a designated limited percentage of a drive speed commanded by the then-prevailing joystick positions, and to then transmit the pump output control signals to the pump output control device so as to
• 1) cause the pump output supplied to the drive motors to remain below a designated percentage at or below that which would propel the vehicle at the designated limited speed percentage for so long as a pump output is beneath a designated percentage of a maximum pump output, and
• 2) cause the pump output to ramp up toward an output percentage that would propel the vehicle at an actual speed commanded by the joysticks when the pump output percentage is above the designated percentage.

A method of operating a utility vehicle including a chassis, at least first and second laterally-spaced driven ground supports that support the chassis on the ground, each ground support device comprising at least one of a track and a wheel, an engine that is supported on the chassis, and a motive drive device that is supported on the chassis and that is operatively coupled to the engine and to at least one ground support, the motive drive device being configured to drive the at least one ground support to propel the vehicle over the ground, the method comprising:

• a. manually translating a drive command device that is electronically coupled to an electronic controller to generate a drive command signal a magnitude of which is dependent upon a degree of actuation of the drive command device;
• and, in response to the translating
• b. using the electronic controller, controlling a drive control system to
• 1) power the motive drive device at a predetermined output that is lower than that that which is commanded by the drive command device for so long as an output of the drive control system is beneath a designated threshold, thereby maintaining vehicle speed lower than a commanded vehicle speed, and
• 2) ramp up the power supply to the motive drive device toward that which is commanded by the drive command device when the output of the drive control system is above the designated threshold, thereby causing the vehicle speed to approach a commanded vehicle speed.