Abstract: A lock-up clutch of a torque converter or the like includes an annular clutch outer mounted in a side cover, a clutch inner connected to a turbine impeller, a driving friction plate axially movably connected to the clutch outer, first and second follower friction plates connected to the clutch inner for movement toward and away from each other with the driving friction plate interposed therebetween, an inner chamber defined between the first and second follower friction plates, and an outer chamber faced by outer sides of the first and second follower friction plates. When the inside of the outer chamber is put at a pressure higher than that in the inner chamber, the follower friction plates can be brought into pressure contact with the driving friction plate, and an urging force on the follower friction plates is not applied to the side cover.

Abstract: In a transmitting system for a small-sized vehicle in which a crankshaft of an engine and an input shaft of a multi-stage transmission are connected to each other through a fluid transmitting device, the fluid transmitting device and a shifting clutch are mounted on the crankshaft. One of the fluid transmitting device and the shifting clutch is connected to the crankshaft, while the other is connected to the input shaft of the multi-stage transmission through a primary reducing device. Provided in the crankshaft are an upstream supply oil passage connected to an oil pump, a downstream supply oil passage connected to portions to be lubricated of the engine, a flow-in bore which permits the upstream supply oil passage to communicate with the inside of the fluid transmitting device, and a flow-out bore which permits the inside of the fluid transmitting device to communicate with the downstream supply oil passage.

Abstract: In a transmitting system for a small-sized vehicle in which a crankshaft of an engine and an input shaft of a multi-stage transmission are connected to each other through a fluid transmitting device, a shifting clutch is interposed between the crankshaft of the engine and the multi-stage transmission in a series relation to the fluid transmitting device. A lock-up clutch is interposed between a pump impeller and a turbine impeller of the fluid transmitting device. Thus, when the multi-stage transmission is to be shifted, the shifting operation can be conducted lightly, in spite of a creep phenomenon of the fluid transmitting device, by bringing the shifting clutch into an OFF state. Moreover, during cruising of the vehicle, the slipping of the fluid transmitting device can be inhibited by the OFF state of the lock-up clutch to enhance the transmitting efficiency.

Abstract: In a transmitting system for a small-sized vehicle in which a crankshaft of an engine and an input shaft of a multi-stage transmission are connected to each other through a fluid transmitting device, the fluid transmitting device and a shifting clutch being mounted on the crankshaft and connected in series to each other. One of the fluid transmitting device and the shifting clutch is connected to the crankshaft, and the other is connected to the input shaft of the multi-stage transmission through a primary reducing device. Thus, when the multi-stage transmission is to be shifted, the shifting operation of the multi-stage transmission can be carried out lightly, irrespective of a creep phenomenon of the fluid transmitting device, by bringing the shifting clutch into its OFF state. Moreover, the burden of torque by the fluid transmitting device and the shifting clutch mounted on the crankshaft which is rotated at a higher speed than that of the input shaft of the transmission is relatively small.

Abstract: A torque converter includes a turbine impeller integrally connected to a pump impeller, a side-cover having a boss and covering the turbine impeller, and a turbine shaft extending through the boss and connected to the turbine impeller. A radial bearing and a one-way clutch are disposed axially adjacent to each other between the boss of the side-cover and the turbine shaft. The radial bearing serves to retain the boss and the turbine shaft concentrically, and the one-way clutch connects the turbine shaft and the side-cover to each other, when a back load is applied to the turbine shaft. Therefore, a load received by a clutch element of the one-way clutch such as a sprig between the turbine shaft and the side-cover is equalized. Thus, when a back load is applied to the turbine shaft, a slipping between the turbine impeller and the pump impeller is prevented, thereby providing a good engine brake effect.

Abstract: The inlet and outlet passages communicating with a water-cooled engine oil cooler for a vehicle, such as a motorcycle, are arranged for bypass of a regulated amount of oil from the inlet passage to the outlet passage to enhance the flowability of the cooled oil. Provision is made for a replaceable flow control orifice between the oil inlet and outlet passages to regulate oil viscosity. Also described is an arrangement providing for mounting the cooler to the crankcase or oil pan surface whereby air flowing past the cooler during movement of the vehicle assists the effects of the cooling liquid.

Abstract: The inlet and outlet passages communicating with a water-cooled engine oil cooler for a vehicle, such as a motorcycle, are arranged for bypass of a regulated amount of oil from the inlet passage to the outlet passage to enhance the flowability of the cooled oil. Provision is made for a replaceable flow control orifice between the oil inlet and outlet passages to regulate oil viscosity. Also described is an arrangement providing for mounting the cooler to the crankcase or oil pan surface whereby air flowing past the cooler during movement of the vehicle assists the effects of the cooling liquid.

Abstract: A cam shaft driving device for an engine which is adapted to operably associate a cam gear located on a cam shaft of an upper portion of an engine body with a driving gear on a crank shaft of a lower portion of the engine body, with this association being effected through the intermediary of a cam idling gear. In this device, first and second wall portions, mutually displaced along the axis of crank shaft rotation of the engine and projecting outwardly and laterally from both sides of the engine body, provide a receiving space. This receiving space is provided between adjacent cylinders in the engine body and is larger in laterally extending width than a diameter of the cylinders, with this width extending laterally of the cylinders and transversely of the axis of rotation of the crank shaft. A single gear holder is located in said receiving space, with this gear holder being mounted on at least one of the wall portions.

Abstract: A multi-cylinder internal combustion engine comprising: first and second crankshafts disposed apart from and parallel with each other; first and second pistons operatively connected to the first and second crankshafts through connecting rods, respectively; and first and second cylinders for slidably accommodating therein the first and second pistons, respectively, both the crankshafts being interlocked with each other to rotate synchronously, the first and second cylinders being disposed adjacent to each other in the axial directions of the crankshafts. Vibrations due to the primary inertial force can be eliminated or alleviated without using a special balancer shaft. The size and weight of the engine are greatly reduced as compared with a conventional horizontally opposed type or V type engine.