Four-wheel vehicle drive system.

摘要

A four-wheel vehicle drive system, comprising an engine having an output shaft (1a) in a lateral direction of the vehicle, a power transmission gear unit (3) including transmission input and output shafts (7,8) having axes of rotation parallel with the engine output shaft (1a), a final reduction gear (25) rotatable about an axis parallel with the transmission input and output shafts (7. 8), the transmission output shaft (8) being in driving engagement with the final reduction gear (25), a gear housing (28) rotatable with the final reduction gear (25). a main transaxle casing (6) having enclosed therein the transmission gear unit (3). final reduction gear (25) and gear housing (28), an auxiliary transaxle casing (27) secured to the main transaxle casing (6), a first wheel drive gear unit (4) to split driving power from the final reduction gear (25) into two components and including a differential gear assembly (38) enclosed in the auxiliary transaxle casing (27) and operative to transmit one of the power components to a pair of road wheels (46, 46 a a second wheel drive gear unit enclosed in the auxiliary transaxle casing (27) and operative to transmit therethrough the other of the two driving power components in a fore-and-aft direction of the vehicle to drive another pair of road wheels (75. 75). and low-and-high speed shifting means (26, 48) including a shift gear assembly enclosed within the gear housing and operative to transfer driving power from the final reduction gear (25) to the differential gear assembly (38) selectively with two different gear ratios