Abstract: The intake valve mechanism employs a back-flow valve to prevent undesirable back-flow of gases from a combustion chamber of an internal combustion engine out an intake port of the chamber during a period of time in which a poppet valve for the intake port of the chamber is open. The back-flow valve is positioned between an intake port valve seat and the intake port poppet valve for blocking the intake port in response to pressure in the combustion chamber. To minimize air-fuel resistance through the intake port, a spring is employed for continuously biasing the back-flow valve to track the movement of the poppet valve, the spring having sufficient strength to prevent the back-flow valve from blocking the intake port when the poppet valve is open until the pressure in the combustion chamber reaches a predetermined value.

Abstract: A gear transmission with overtop or overdrive for automotive vehicles includes an overdrive gear mechanism mounted immediately after the rear end wall of a transmission case. The overdrive gear mechanism includes a pair of overdrive gears, one located on the output shaft of the gear transmission and the other on the countershaft of the gear transmission, operable to rotate the output shaft at a higher rotational speed than the input shaft. An overdrive synchronizer assembly is mounted rearwardly of the overdrive gears such that the direction for actuating the overdrive synchronizer assembly coincides with the direction that a gear shift lever of the vehicle is shifted to obtain the overdrive position.