Theory Of Operation - Life Fitness 4000 Service Manual

Life Fitness Model 4000 Treadmill

THEORY OF OPERATION

The operational functions of the Life Fitness Model 4000 Treadmill are accomplished by four main components: the
Control Board, the Display Console, the Drive Motor and the Lift Actuator. The Treadmill user and the control
board provide input to the display console. The display console then determines the appropriate action to be taken
and passes low level signals to the control board. The control board converts low level signals to high level signals
and forwards them to the drive motor and the lift actuator to execute the requested command. All of the
"Intelligence" within the Treadmill is located in the display console.
Control Board
The control board provides power for the Treadmill, acts as an interface between the display
console, drive motor and lift actuator, and also acts as an additional interface between the speed
sensing and lift limit switches. The drive motor trigger, lift actuator time and direction, and safety
power relay signals are received from the display console and routed through the control board to
execute a command. Speed sensing and lift limit signals are also passed through the control board
to the display console.
Display Console
The display console is the user interface that allows selection from the various programs and options
offered by the Treadmill. The display console provides all of the "Intelligence" within the Treadmill,
controls the information displays, and monitors the keypad and safety switches. It determines the
drive motor and lift actuator actions to suit the chosen Life Fitness aerobic training program and it
also accommodates the optional heart rate receiver.
Drive Motor
The drive motor is the component responsible for moving the striding belt. The speed sensor, located
on the drive motor, sends pulses through the control board to the display console which converts
them to the striding belt speed. The display console adjusts the power to the drive motor to maintain
a constant speed to the striding belt resulting in a more comfortable "feel".
Lift Actuator
The lift actuator is the component responsible for raising and lowering the incline level of the
Treadmill. The display console, through the control board, will raise and lower the lift actuator for the
appropriate amount of time and incline required by a specific command. The "Home" lift limit switch
signals the display console when the lift actuator is at 0% incline. The lift actuator also has its own
internal built-in limit switches.
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