Tham khảo tài liệu 'lubricants and lubrication part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 258 10 Gear Lubrication Oils is used which allows to determine the load dependence of the static and dynamic friction and friction stability during a certain period of time. Figure shows typical friction coefficients of a four-stage load-collective test. Figure compares the friction charcteristics at the 1st and at the 50th cycle of two different ATF technologies. In order to achieve a smooth and soft gear-shifting it is tried to reach a relatively high dynamic friction coefficient at the beginning of the gear-shifting operation which will decrease during braking and then fade to an even slightly lower static friction coefficient. During the test oil A at first shows such a desired friction curve in the 1st cycle. It is however not able to constantly maintain this behavior as shows the 50th cycle. The longterm friction coefficient of oil A towards to the 50th cycle sinks as well. In this 0 00 0 B 0 20 A LSI - Cycle 10 LS2 - Cycle 15 LS3 - Cycle 20 LS4 - Cycle 21 0 20 0 16 o 0 12 o 0 08 0 04 OilA Oil A Oil A Oil A OilB Oil b Oil b Oil b 1 0 0 1 0 2 0 0 0 1 0 2 0 0 0 1 0 2 0 0 0 1 0 2 0 16 o 0 12 0 08 0 04 Time s 0 00 0 0 0 1 0 2 0 0 0 1 0 2 0 0 0 1 0 2 0 0 0 1 0 2 LS Loadstage Time s Fig. DKA 1B test run different ATF technologies. Wet clutch-loadstage test A. Run-through No. 1 at 4 Loadstages LS 1 to LS 4 66 cycles analogous to 1st run B. Run-through No. 50 at 4 loadstages LS 1 to LS 4 3300 cycles analogous to 50st run multiplied with 66 cycles each. Gear Lubrication Oils for Motor Vehicles 259 case the user will prefer oil B which even after the 50th cycle does not display such a high increase in the static friction and the long-term friction of which shows a relatively constant behavior over all. To test the gearshift and friction behavior especially in case of permanent slip of the friction partners the gear manufacturer ZF has developed another test bench. The so-called GK test bench or CSTCC continuously slipping torque converter clutch
