Theory Of Operation - Life Fitness 3500 Service Manual

Life Fitness Model 3500 Treadmill

THEORY OF OPERATION

The operational functions of the Life Fitness Model 3500 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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