Tham khảo tài liệu 'advanced vehicle technology 2 episode 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Fig. Illustration of pulley and belt under- and overdrive speed ratios Fig. Steel belt construction Hydraulic control system Fig. The speed ratio setting control is achieved by a spur type hydraulic pump and control unit which supplies oil pressure to both primary and secondary sliding pulley servo cylinders Fig. . The ratio settings are controlled by the pressure exerted by the larger primary servo cylinder which accordingly moves the sliding half pulley axially inwards or outwards to reduce or increase the output speed setting respectively. This primary cylinder pressure causes the secondary sliding pulley and smaller secondary servo cylinder to move proportionally in the opposite direction against the resistance of both the return spring and the secondary cylinder pressure this being necessary to provide the correct clamping loads between the belt and pulleys walls. The cylinder pressure necessary to prevent slippage of the belt varies from around 22 bar for the pull away lowest ratio setting to approximately 8 bar for the highest overdrive setting. The speed ratio setting and belt clamping load control is achieved via a primary pulley position senser road assembly. 152 Fig. Transaxle continuously variable belt and pulley transmission layout However engine and road speed signals are provided by a pair of pitot tubes which sense the rate of fluid movement this being a measure of speed be it either under the influence of fluid flow caused by the engine s input or by the output drive relating to vehicle speed. Epicyclic gear train construction and description Figs and Drive in both forward and reverse direction is obtained by a single epicyclic gear train controlled by a forward multiplate clutch and a reverse multiplate brake both of which are of the wet type 153 immersed in oil Fig. . The forward clutch is not only used for engagement of the drive but also to provide an initial power take-up when driving away .
