|
|
|
CHERY AUTOMOBILE CO., LTD Automatic Transmission Fault Diagnosis Manual 174 scope of 1 st gear. The lock valve also prevents the manual downshift from 2 nd to 1 st gear when it is beyond the scope of 1 st gear by controlling the pressure in brake C’s oil circuit.
11. 2 nd gear lock valve When the control handle is in position 2, the lock valve controls the linear oil pressure at 2 nd -3 rd
shift valve and prevents it from upshift to 3 rd gear. Hence, the vehicle speed is limited within the scope of 2 nd gear. The lock valve also prevents the manual downshift from 3 rd to 2 nd gear when it is beyond the scope of 2 nd gear by controlling the pressure in brake C’s oil circuit.
12. 2 nd -3 rd -4 th upshift valve 2 nd -3 rd –4 th upshift valve ensures that the transmission has upshift in the order of 2 nd –3 rd –4 th gear. When the planetary mechanism engages at 3 rd gear drive ratio, the upshift valve releases the oil pressure given by governor on 3 rd -4 th shift valve. Since the transmission could not jump directly from clutch A to brake C for engagement, the direct upshift from 2 nd to 4 th gear is also impossible.
13. 4 th -3 rd -2 nd downshift valve 4 th -3 rd -2 nd downshift valve ensures that the transmission has downshifts in the order of 4 th –3 rd –2 nd
gear. The downshift valve controls the pressure on 2 nd -3 rd shift valve’s oil circuit and maintains it at position 3 until the planetary gear engages at 3 rd gear. Since the transmission could not jump directly from clutch A to brake C for engagement, the direct downshift from 4 th to 2 nd gear is also impossible. 14. 3 rd -4 th traction valve 3 rd –4 th traction valve controls the brake A’s oil pressure at 4 th gear. When 3 rd -4 th upshift valve works, clutch A drains the oil through the traction valve. Only when brake C could transfer the engine’s output torque, the traction valve drains the oil.
15. 4 th -3 rd traction valve 4 th –3 rd traction valve works as the oil feed valve on clutch A’s shuttle valve. When 4 th -3 rd
downshift valve works, it fills the hydraulic fluid required by clutch A in advance.
16. 4 th –3 rd downshift valve 4 th –3 rd downshift valve works as the oil pressure maintaining valve for brake C until clutch A is full of oil. Brake C also drains the oil through 4 th –3 rd downshift valve.
17. Time control valve During transition between clutches, the time control valve controls the delay time for the clutch’s engagement and disengagement. The delay time is same with the shuttle valve’s buffer time and irrelevant with 4 th -3 rd traction valve and 4 th -3 rd downshift valve.
18. Throttle control valve The throttle control valve is on the power transfer oil circuit and controls the oil pressure on time control valve and brake C by controlling the time of oil feed. |