5 inclusive depict the development apparatus employed in the fig1 of the printing machine turning now to fig2 there is shown the detailed structure of developer unit 28 as shown therein housing 62 has a chamber 64 for storing a supply of developer mix therein paddle wheel 66 includes a substantially tubular member 68 having vanes 70 extending outwardly in a radial direction therefrom paddle wheel 66 rotates in the direction of arrow 72 to advance the developer material to magnetic brush 30 magnetic brushes 30 32 34 and 36 form a blanket of developer material moving in the direction of arrow 12 and positioned closely adjacent to the latent image recorded on belt 10 in this manner the toner particles are attracted electrostatically from the carrier granules to the latent image in image configuration each of the developer rollers rotate in the direction of arrows 74 76 78 and 80 respectively after the first original document has been reproduced in the first color for example black the next successive original document may be reproduced in a second or different color on the same or another copy sheet changing developer material colors requires s cleaning the initial charge of developer material from chamber 64 of housing 62 mounted for rotation within chamber 64 of housing 62 are four magnetic brush developer rollers 30 32 34 and 36 positioned with their axis parallel with one another below belt 10 each magnetic brush developer roller comprises an outer cylinder or tubular member 82 made of a non magnetizable.