TM-9-2520-234-35 Technical Manual for M109 Transmission XTG-411-2A Download

PAR 18-19 DESCRIPTION AND OPERATION OF CHAP 2, SEC II MAIN TRANSMISSION ASSEMBLY blies 10 and 69 are installed through lugs on the rotating brake apply cams. Adjust- ing nuts 20 (fig. 378, fold-out 7) and 14 (fig. 380, fold-out 9) are installed on the threaded ends of link assemblies 10 and 69 (fig. 379, fold-out 8). Ratchets 21 (fig. 378, fold-out 7) and 15 (fig. 380, fold-out 9) are held in engagement with the adjust- ing nuts by springs 22 (fig. 378, fold-out 7) and 16 (fig. 380, fold-out 9), washers 23 (fig. 378, fold-out 7) and 17 (fig. 380, fold- out 9), and pins 24 (fig. 378, fold-out 7) and 18 (fig. 380, fold-out 9). (3) Two air valve plate assem- blies 36 and 43 (fig. 379, fold-out 8) are pivoted on pin 45 in bracket 40. Springs 39 and 42 hold the valves in a closed posi- tion over passages in the transmission rear housing when the brakes are mech- anically applied. b. Operation (fig. 379, fold-out 8) — (1) When either of brake apply shafts 84 or 97 are rotated (clockwise viewed from right of transmission), brake apply cam 75 or 83 moves the cam follow- er 6 or 62 and cam follower link 3 or 60 forward. Link assembly 10 or 69, being connected to the cam follower link, moves forward. This rotates the rotating brake cam clockwise, applying the brake. (2) Simultaneous with rotation of the brake cam to apply position, brake air valve 36 or 43 is forced to closed position by its spring. Note that the valves are held open (upward) against spring pressure (by the brake cam extensions) when the brakes are released. The air valves control the admission of air to the intake side of the brake coolant pump. Thus, when brakes are applied, no air is admitted and oil is pumped. When brakes are released, air is admitted, preventing the pumping of oil. (3) Brake adjustment is made by rotating the brake adjusting nuts. A large screwdriver can be inserted in radial slots in the nuts. The spring-loaded ratchets re- tain the nuts in the position to which they are adjusted. 19. RELAY VALVE BODY ASSEMBLY a. Components (fig. 382, fold-out 11) — (1) The relay valve body assembly includes valve body 73, cover assembly 60, cover 68, plug 78, springs 66 and 75, pin 74 and valves 64, 65 and 76. In addition, bolts, gaskets, plugs, washers and minor parts are included. Valves 64, 65 and 76 are identical. Springs 66 and 75 are iden- tical. The valves and valve body are aluminum. (2) Valves 64 and 65 are installed in a common bore in valve body 73. The short stem ends of these valves butt to- gether and both valves move lengthwise as a unit in their bore. Spring 66 moves them to one end of the bore when no hy- draulic pressure acts at that end. Cover 68 closes the spring end of the bore. Cover assembly 60 closes the opposite end. (3) Valve 76 is installed in another bore which is parallel to the first bore. Spring 75 moves the valve to the end of the bore opposite the spring when no hydraulic pressure acts at that end. Pin 74 limits the movement of the valve against spring 75. Plug 78 closes the bore. (4) The bores in which the valves operate have annular channels which re- ceive oil from or direct oil to passages which register with passages in oil transfer plate 79 upon which the valve body assem- bly is mounted. Transfer plate 79 is, in turn, mounted upon transmission rear housing cover 95 and directs oil to various passages in the cover. (5) Valves 64, 65 and 76 each have five lands which separate the various oil passages. Lengthwise movements of the valves interconnect certain passages when the valves are at one end of the bore, and other when at the opposite end. b. Operation (fig. 372, fold-out 1 and fig. 382, fold-out 11) (1) Valve 76 is the drive clutch relay valve. Its position in the valve body bore determines whether the output clutches or the geared steer clutches are Change 2 19