Each feed of this oiler is provided with a separate pump element consisting of a pump body plunger and a piston valve, the suction and feed ducts connecting directly with the pump body of their respective elements. With this construction, pump elements may be replaced or added. The oiler requires no attention other than to be supplied with oil; and the opening and closing of the valves, pet cocks, etc., on starting and stopping the machine is rendered unnecessary. The correct and regular operation of the elements may be verified by observation of the reciprocating movements of the regulating screws. Each pump plunger is provided with an adjusting screw through which the feed may be regulated from 0 to 0.2 cubic centimeters for each stroke. The Bosch Oiler (Fig. 121) being positively driven by the machine that it supplies, the oil fed is in all cases proportional to the engine speed; overloads are thus automatically taken care of. The circular arrangement of the elements of the Bosch Oiler permits the device to be driven by a single shaft, and the oil is forced through the feeds from a single reservoir to the required points of application. A pump element consists of a pump body 1, a pump plunger 2 and a piston valve 3, and is supported on the base plate 13. The elements are arranged concentrically about the drive shaft in such a manner that the pump plungers form a circle around the circle formed by the piston valves. [Illustration: Top View of Bosch Force Feed Oiler. ] [Illustration: Fig. 121. Cross-Section Bosch Oiler. ] The pump cam disk 20 and the valve cam disk 22 are set on the drive shaft at other than a right angle with its axis, and the rims of the disks are gripped by slots formed in the heads of the pump plungers and piston valves. The relation of these cam disks is such that the valve cam disk is 90° in advance of the plunger cam disk. The valve cam disk is solid on the drive shaft, but the pump cam shaft is loose and driven through a lug on the valve cam disk. When the drive of the pump is reversed, the lug on the valve cam disk frees itself and again takes up the drive of the pump cam disk, after the drive shaft has made a half revolution. Regulating screws 4 are set in the slotted heads of the pump plunger, and by means of this the back-lash or play of the cam disk may be regulated. The regulating screws are provided with lock nuts, and project through the cover of the oil tank housing, being exposed by the removal of the filler cover 42. The filler opening is provided with a removable strainer to prevent the entrance of foreign particles into the oil tank. Pump shaft 14 is driven through worm gear 23 which meshes with worm 24 on drive shaft 25; drive shaft 25 projects from the oiler housing, and is coupled with the driving shaft of the machine to be lubricated. Base plate 13 is attached to the oiler cover by three stud bolts, thus permitting the removal of the entire oiler mechanism from the housing.