Lift device and method of controlling on a grade

A method of controlling a lift device, the method comprising:

• receiving a requested speed for the lift device from a user input;
• propelling the lift device at the requested speed via an electric motor connected to a wheel, the electric motor electrically connected to a traction battery;
• determining that the requested speed is greater than a predetermined speed when the lift device is on a non-zero grade, the predetermined speed being dependent on the grade;
• limiting a speed of the lift device to the predetermined speed by commanding the electric motor to output a braking torque and provide electrical power to the traction battery while the lift device is on the non-zero grade;
• and
• commanding a parking brake to engage to stop the lift device if the speed of the lift device exceeds the predetermined speed while on the non-zero grade.

A propulsion device comprising:

• an electric motor adapted to be coupled to at least one wheel;
• a traction battery in electrical communication with the electric motor;
• a user input to control a speed of the at least one wheel by inputting a requested speed;
• and
• a controller configured to, in response to the device being on a non-zero grade and if the requested speed is greater than a predetermined speed, command the electric motor to output a braking torque and provide electrical power to the traction battery, and limit the speed of the device to the predetermined speed.