Abstract: In a multi-axle drive vehicle having a first axle which is directly coupled to a power source, and a second axle which is coupled to the power source by way of a coupling such as a viscous coupling which is adapted to transmit torque as a mathematical function of a difference in rotational speed between its input end and output end, to the end of eliminating the problems arising from transmission of braking force between the wheels of difference axles, the vehicle is further provided with a clutch for selectively interrupting transmission of power from the power source to the second axle, a brake sensor for detecting activation of a brake system of the vehicle, and a control unit for activating the clutch when the brake sensor has detected activation of the brake system. The conditions for activating the clutch may further include that the vehicle is running at a high speed which may be detected either directly or from a shift position of the power transmission system of the vehicle.

Abstract: A method and mechanism for selectively transmitting and interrupting power between an input shaft and an output shaft arranged in coaxial relation in which a rotary member is coupled to one of the shafts to provide first and second states therebetween and wherein in the first state the rotary member is free to rotate and rotation is transmitted between the input and output shafts, whereas in the second state the input shaft can rotate relative to the output shaft and transmission of rotation is interrupted. The rotary member and the one shaft are angularly rotated relative to one another between first and second relative positions in the first and second states, and rotation of the rotary member is halted by a disc brake in the second state.

Abstract: A drive power transmission device includes: a first shaft for receiving drive power transmitted from a drive source; a second shaft having a coupling shaft portion at a front end thereof; a coupling housing comprising a cover body having a front portion operatively coupled to a rear end of the first shaft and a rear portion including a central bearing portion in which a distal end of the coupling shaft portion is rotatably supported, and a tubular member having a front open end in which an outer circumference of the cover body is fitted and a rear boss end having a central through hole in which a proximal portion of the coupling shaft portion is rotatably supported, the cover body, the boss end, the coupling shaft portion, and the tubular member jointly defining a cylindrical fluid chamber filled with a fluid; a viscous shear coupling mechanism disposed in the fluid chamber for transmitting the drive power from the first shaft through the fluid to the second shaft; and a centrifugal clutch mechanism disposed

Abstract: To the end of eliminating the problems arising from substantially rigid connection between a front wheel set and a rear wheel set in a four-wheel drive vehicle, there is provided a power transmission system in which a torque-dependent power transmission device is provided between the front wheel set and the rear wheel set so that both the wheel sets are substantially rigidly connected to each other in a low torque range and rotational power is transmitted only from the front wheel set to the rear wheel set in a high torque range. The power transmission device of this kind can be conveniently formed by a parallel combination of a one-way clutch and a torque limiter.

Abstract: A power transmission system suitable for use in a four-wheel drive motorcar. A torque generated from a power source is directly transmitted to a first axle, and it is transmitted to a second axle via a torque transmission device making use of viscosity of fluid. Between the power source and the second axle is provided torque limiter means for limiting a torque transmitted to the second axle to smaller than a preset value. Even if the torque transmission device should take a locked condition, an excessively large torque would not be exerted upon the respective parts in the power transmission system, and hence a torque transmission system can be made light in weight.

Abstract: An improvement is provided in a differential gear which includes an input shaft, a differential casing adapted to be rotated by the input shaft, a differential pinion shaft radially extending within the differential casing and a plurality of differential pinion gears rotatably mounted on the differential pinion shaft. A pair of side gears having a rotation axis common to that of the differential casing and meshing with the pinion gears, and a pair of output shafts fixed to the side gears. The improvement comprises a centrifugal weight member slidably mounted on the differential pinion shaft and radially inwardly biased, and a multiple disc clutch provided between the differential casing and the output shafts. The clutch is adapted to be engaged in response to the radially outward movement of the centrifugal weight member.

Abstract: A drive power transmission device includes an input carrier having a front portion for receiving drive power from a drive source and a tubular rear portion, a planetary gear mechanism having a sun gear disposed coaxially in the tubular portion of the input carrier, a plurality of planet gears meshing with the sun gear and rotatably supported on a periphery of the tubular portion, and a ring gear mounted concentrically on the tubular portion and meshing with the planet gears, a first output shaft coupled to and supporting the sun gear, an intermediate tubular member connectable to the first output shaft and a rear end of the tubular rear portion of the input carrier and disposed concentrically with the first output shaft, an outer tubular member connectable to the ring gear and disposed concentrically with the intermediate tubular member, a viscous shear coupling mechanism interconnecting the outer tubular member and the intermediate tubular member, and a second output shaft coupled to and supporting the outer