A gyroscopically-responsive power assisted moment arm is disclosed for use in connection with vehicles such as load carrying devices. A moment arm extends to a pivot point such that when a longitudinal force is applied at the moment arm, a sensor senses such force and outputs an energizing signal to a motor to drive a wheel. If a rotational or vertical force is applied to the moment arm, the motor need not be driven. According to the invention, therefore, a power assist can be provided to a user to drive a wheel in a desired direction of transport while not causing drive during tipping or unloading of the load carrying portion of the vehicle. Such an apparatus can be advantageously applied to a power assisted wheelbarrow, as one exemplary application.