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

PAR 31-34 OPERATION OF HYDRAULIC SYSTEMS CHAP 2, SEC IV are open. The brake coolant pump is operat- ing but air is being drawn through the open air valves and directed to the brakes. If the brakes are applied (except hydraulically in steering), the air valves close and oil is drawn from the sump, through check valves, and delivered to the brake plates. d. Fig. 7 illustrates partial opening of the throttle which produces TV pressure at the throttle regulator valve. Refer to par. 30f, g , h, and i, above, for a complete explanation of the function of the throttle and throttle regu- lator valves. 32. HYDRAULIC SYSTEM FUNCTION- SECOND GEAR (fig. 8) Note. Refer to par. 48 and fig. 24 for the torque path through the power train. a. The function of the hydraulic system in second gear is the same as that in first gear except that drive to the power train out- puts is through the output clutches rather than through the geared steer clutches. b. When the manual selector valve is shifted to the second gear position, the low- range clutch is engaged but no signal pressure is present. Because no signal pressure exists, the drive clutch relay valve is held downward by the spring at its upper end. This alines the hydraulic system to direct steer pressure to the right- and left -output clutches. c. Fig. 8 illustrates the lockup shift valve in its downward position and shows main pres- sure applying the lockup clutch. Note the branch of the lockup clutch line that directs pressure to the top of the main-pressure regulator valve. Downward movement of the valve exhausts oil to the sump, reducing main pressure. Note. If pump speed is not sufficient to provide a larger volume of oil than that flowing to the converter and lost by leakage, the main-pressure regu- lator valve may not move downward sufficiently to exhaust oil. d. At higher speeds, the shift inhibitor plunger is extended and prevents shifting to first, neutral or reverse gears. 33. HYDRAULIC SYSTEM FUNCTION - THIRD GEAR (fig. 9) Note. Refer to par. 49 and fig. 25 for the torque path through the power train. a. In third gear, the hydraulic system operates as in second gear except that main pressure applies the intermediate-range clutch and that reverse 2, third and fourth signal pressure is directed to the lower end of the steer relay valve. b. When the manual selector valve is in third-gear position, the intermediate-range clutch is charged and signal pressure is di- rected to the steer relay valve. Signal pres- sure pushes the valve upward against spring pressure and a1ines the steer circuit for geared steer. c. At higher speeds, the shift inhibitor plunger wi11 extend and prevent shifting to lower gears, neutral and reverse gears. 34. HYDRAULIC SYSTEM FUNCTION – FOURTH GEAR (fig. 10) Note. Refer to par. 50 and fig. 26 for the torque path through the power train. a. Conditions in the hydraulic system during fourth-gear operation are the same as in third gear except that the high-range clutch is engaged instead of the intermediate-range clutch. The only valve at a different position is the manual selector valve. b. When in the fourth gear position, the manual selector valve lever will permit the shift inhibitor plunger to extend, at higher speeds, and block any shift from fourth gear. c. Full-throttle opening is illustrated, showing how both T and TV pressures are pro- duced. Note that T pressure is equal to maxi- mum TV pressure but that T pressure is di- rected to a different area. 31