TM 9-2910-226-34 NOTE The hydraulic heads on code F and G in- jection pumps, (fig. 1-14 and 1-15) had additional passages that directed the flow of lubricating oil to the lower portion of the fuel plunger and the plunger drive gear. If these hydraulic heads are replaced by later model heads it will be necessary to plug the oil passage in the injection pump housing with parts kit 5704374. d. The fuel plunger is lapped and fitted into the hydraulic head as well as in the plunger sleeve. Two parallel flat surfaces on the lower extension of the fuel plunger lock the plunger drive gear with the plunger guide (M). The plunger guide is designed to shear if the fuel plunger freezes, e. The drive gear thrust washer (Q) is placed between the drive gear and hydraulic head to take the thrust of the plunger drive gear, The spring upper and lower seats (L and H) and plunger inner spring (K) are held on the plunger by two plunger locks (J), The plunger button (X) mates the round surface of the fuel plunger end to the flat surface of the tappet guide (G). The preceding components are fastened to the head by the drive gear retainer (N). This retainer is cut away to permit the meshing of the plunger drive gear with the quill shaft gear and is also used for fuel pump timing. 1-9. Overflow Valve Assembly. The overflow valve assembly (A, fig. 1-13 ) returns the excess fuel from the hydraulic head to the vehicle fuel tank. The valve assembly is located on the fuel outlet passage of the hydraulic head. It consists of an overflow valve and valve spring which maintains a constant fuel pressure in the hydraulic head. The overflow valve has a small opening which allows any air ac- cumulation in fuel passages to escape. The opening also serves as a continuous bleed of fuel to permit cooling of the pump. 1-10. Camshaft. NOTE The key letters shown in parentheses refer to figure 1-16. The camshaft (ZZ) is supported at the front of the fuel pump housing by the camshaft ball bearing (AB) and at the rear by the camshaft bushing type bearing (XX). The camshaft is comprised of a shaft with a three-lobed cam and a spiral worm gear. The worm gear drives the quill shaft and the fuel supply pump. 1-11. Tappet Assembly. NOTE The key letters shown below in parentheses refer to figure 1-16. The tappet assembly is located between the camshaft and the lower end of the fuel plunger. It consists of a tappet roller (YY), tappet roller pin (F), and a tappet guide (G). The tappet guide con- tains a slot which rides on the tappet guide pin in the injection pump housing. 1-12. Quill Shaft Assembly. NOTE The key letters shown below in parentheses refer to figure 1-13. The quill shaft assembly transmits the rotary motion of the camshaft to the fuel plunger at one-half camshaft speed. The quill shaft assembly consists of a quill shaft (L), quill shaft bushing (K) two shaft spacers (H), and a camshaft driven gear (G). The quill shaft assembly is held in position in the injection pump hous- ing by a machine screw (J). 1-13. Governors (Typical). NOTE The key letters shown below in parentheses refer to figures 1-16 and 1-17, except where otherwise indicated. a. The governor, with its weight and spider assembly attached to the camshaft, is an integral part of the fuel injection pump. The governor is a variable speed, mechanical and centrifugal type. The governing action is accomplished by two governor weights (UU) acting against a movable sliding sleeve (VV) which is backed up by governor inner and outer springs (RR and SS) loaded in opposite directions. (1) The governor on code A injection pump (fig. 1-1 7) is the same except a torque control link ((D), fig. 1-18) has been added. (2) The control link retards governor action during automatic transmission shift and does not allow engine speed or torque increase during the change of gear ratios within the transmission. This action alleviates shift shock to the transmission. KEY to fig. 1-18 G A B C D E F E J K L M N P Weight and spider assembly Oil baffle Torque link spring Torque link Guide Sliding stop wedge Smoke limit Stop plate Fulcrum lever assembly Torque link pin Contact surface Operating shaft Torque link pin Contact surface 1-20