TM-9-2520-234-35 Technical Manual for M109 Transmission XTG-411-2A Download
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*C2 CHAP 2, SEC V TORQUE PATHS PAR 40-43 40. HYDRAULIC SYSTEM FUNCTION - DURING TOW OR PUSH STARTS OF VEHICLE (fig. 19) a. When it is necessary to start the ve- hicle engine by towing or pushing the vehicle (refer to TM 9-2300-216-10), the manual se- lector valve must be placed in second gear position. b. The function of the hydraulic system in second gear during a tow- or push -starting operation is the same as that described for second gear in par. 32, above, and illustrated in fig. 8. However, during such an operation (until the engine begins to rotate), the input driven pressure pump can not supply main pressure to the system. The output driven pressure pump must supply main pressure until the clutches (output and low range) engage and until torque is transmitted to the vehicle engine. c. The output driven pressure pump draws oil, through the sump screen, from the power train sump. The output of the oil pump unseats a check valve and flows into the cavity surrounding the main oil screen assembly. Thereafter, the oil flow is the same as main pressure oil flow for second gear under any other condition. d. The purpose of the check valve in the output driven pressure pump output line is to prevent a back flow of main pressure into the output driven pump. In neutral, the output driven pump is not rotating and there is some loss by leakage through the pump. In reverse gears, the pump rotates in a reverse direc- tion and would (except for the check valve) actually pump oil out of the main pressure line and return it to the sump. Section V. TORQUE PATHS THROUGH POWER TRAIN 41. GENERAL a. Figure 20 is a schematic view of the power train without the output drive assem- blies. All of the principal components through which torque flows are identified. Figure 21 is a cutaway view of the left-output drive as- sembly, colored to indicate the torque path. Subsequent figures, 22 through 34, are colored schematic views, illustrating the torque paths for the conditions indicated in each view. Ar- rows on components indicate the direction of rotation of such components. b. Explanations of hydraulic actions under corresponding conditions are in pars. 28 through 40 of this chapter. c. To avoid needless repetition, refer- ences are made to preceding explanations where applicable. 46 42. TORQUE PATH - INPUT TRANSFER GEARING (fig. 20) Torque is transmitted from the engine to the input transfer gearing by a splined coup- ling shaft. Two idler gears transmit torque from the input transfer drive gear to the con- verter cover drive gear. The input rotation (at coupling shaft) is counterclockwise when viewed from the left side of the power train. Rotation of the torque converter is clockwise, There is a speed increase ratio of 0.611 to 1.000 between the engine and torque converter. 43. TORQUE PATHS - TORQUE CONVERTER AND LOCKUP CLUTCH (fig. 20) a. Torque is transmitted from the input transfer gearing to the range gearing by either the torque converter or lockup clutch. When the lockup clutch is released, torque is trans-