The machine uses 4 drum units (Y, M, C, Bk), each consisting of a drum unit, developing cylinder, primary charging roller, and carrier and housed under the ITB.

The machine supplies toner as follows:

The toner coming from the hopper assembly is moved to the toner transport feedscrew A of the drum unit; then, it is moved farther by the toner transport feedscrew

B while being mixed with carrier to reach the developing cylinder. During printing, a layer of toner is formed on top of the layer of carrier deposited on the devel-

oping cylinder; the toner then jumps (toner projection) to the photosensitive drum for development.

The residual toner on the developing assembly after development is scraped off by the cleaning blade, and is moved by the waste toner feedscrew for collection

inside the waste toner case.

The following 3 types of electrical loads are associated with the supply path:

- motor: 2 types (development motor, drum/ITB motor)

- clutch: 1 type (developing sleeve clutch)

[1] Developing cylinder

[2] Photosensitive drum

[3] Waste toner feedscrew

[4] Primary charging roller

[5] Carrier

[6] Toner transport feedscrew A

[7] Toner transport feedscrew B

M1: drum/ITB motor