A method of controlling a power feed to a load, wherein the load can be connected to an apparatus for the power feed and the power fed to the load has clock-controlled signals. Through the use of digitalink-jet print technology, retailers, such as pharmacies and fast food restaurants apply store-specific, localized advertising and promotional material to bags, trayliners and other materials. The steering mechanism is provided with a rotation angle sensor for detecting a steering angle \u03b8 of the left front wheel and a proximity switch for detecting whether or not the front wheel is in a straight-ahead state. The display apparatus displays an image using the modified image data by the data modifier.