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

CHAP 2, SEC IV OPERATION OF HYDRAULIC SYSTEMS PAR 37 feed pressure. Maximum downward movement will produce maximum steer feed pressure. (3) Right-steer feed pressure flows to the steer relay valve which directs it to the right brake. The clutch-brake method is used for first-gear steer. In right steer, the right brake is applied. Full-right steer stops the right output of the power train. Partial-right steer slows the right output. (4) Upward movement of the left-steer valve does not interrupt the flow of steer pres- sure to the left-drive clutch (geared steer clutch). This upward movement, however, does open a passage through which oil can flow, through an orifice, to the steer coolant feed line. The steer coolant feed line carries oil to the steer relay valve, where it is sent to the right brake, through the clutch-brake steer coolant line. (5) A ball-type check valve is located between each of the steer feed lines and steer coolant feed lines. The upper check valve opens when the application of right steer is discontinued, and allows the brake apply pres- sure to exhaust through the clutch-brake steer coolant line. (6) In right steer in first gear, the right- drive clutch (geared steer clutch) is released, the right brake is applied and cooled, and the left-drive clutch (geared steer clutch) remains engaged and continues to drive. b. Second Gear, Full-left Steer — (fig. 14) Note. Refer to par. 54 and fig. 30 for the torque path through the power train. (1) The hydraulic system will function in second gear steer in the same manner as described for second-gear straight travel in par. 32, above, except for the position of the steer valves and the flow of oil to the drive clutches and brakes. (2) In left steer, the steer control shaft is rotated counterclockwise. This rotation moves the right- steer valve upward while, the left-steer valve moves downward. Flow to the left-drive clutch (output clutch) is blocked. A regulated steer feed pressure is sent to the steer relay valve. The steer relay valve sends oil to the left brake through the left-brake apply line. (3) The flow to the right-drive clutch (output clutch) is not interrupted and the clutch continues to drive the right output. The right- steer valve supplies steer coolant feed to the left brake. The left-brake apply pressure can exhaust through the lower check valve (between steer feed and steer coolant feed lines) and the clutch-brake steer coolant line, when applica- tion of steer is discontinued. 38. HYDRAULIC SYSTEM FUNCTION – THIRD AND FOURTH GEARS, STEER a. Third Gear, Full-right Steer — (fig. 15) Note. Refer to par. 55 and fig. 31 for the torque path through the power train. (1) The hydraulic system will function in third-gear steer in the same manner as de- scribed in par. 33, above, except for the posi- tion of the steer valves and the flow of oil to the drive clutches and steer clutches. (2) Downward movement of the right- steer valve and the resulting oil flow is de- scribed in par. 37a(2), above. — (3) Right-steer feed pressure flows to the steer relay valve which directs it to the right- geared steer clutch, through the geared steer clutch apply line. The geared steer method is used in third-gear steer. In right steer, the right-geared steer clutch is applied. Full-right steer fully applies the steer clutch so that no slippage occurs. Partial-right steer allows the steer clutch to slip somewhat. (4) Upward movement of the left-steer valve does not interrupt the flow of steer pres- sure to the left-drive clutch (output clutch). This upward movement, however, does open a passage through which oil can flow, through an orifice, to the steer coolant feed line. The steer coolant feed line carries oil to the steer 38