Abstract: An automatic power transmission of an automotive vehicle includes various frictional elements and frictional brakes and can prevent a shift shock from occurring by increasing a working hydraulic pressure applied to a certain frictional element (forward clutch F/C) so as to make fast a reengagement of the certain frictional element when a down-shifting from a high gear speed range to a low gear speed range occurs. In a preferred embodiment, the working hydraulic pressure present during the down-shifting is introduced into an accumulator so as to disable a stroke of the accumulator. In another preferred embodiment, a time at which a shifting solenoid (A) is turned from its ON state to its OFF state is retarded after a control valve control solenoid (C) is turned from its OFF state to its ON state in response to an instruction of a controller to shift down the gear speed range. In addition, a fuel consumption of the associated engine is improved by an extension of a lock-up interval off a torque converter.

Abstract: Under a higher speed gear position of the transmission, a control valve can drain a hydraulic pressure of a forward clutch to cause the forward clutch to take a disengaged condition. With this, undesired friction of a forward one-way clutch under such higher speed gear position is suppressed. A fail-safe system is employed for recovering an engaged condition of the forward clutch even when the control valve is stuck at such pressure draining position.

Abstract: Magnetic recording medium is disclosed which comprises a non-magnetic support having coated thereon a magnetic layer mainly containing ferromagnetic metal particles and a binder:(1) wherein the non-magnetic support is a polyester film having a thickness of 4 to 12 .mu.m, (b) an F5 value in a machine direction of 16 kg/mm.sup.2 or more, (c) a breaking strength in a machine direction of 25 kg/mm.sup.2 or more, (d) a breaking elongation in a machine direction of 90% or less, (e) a surface roughness (Ra) of 0.01 to 0.03 .mu.m, and (f) a fish eye (FE), which is shown in terms of height (H), of 6H or more having 0 per 100 cm.sup.2, a fish eye of 5H having 2 or less per 100 cm.sup.2 and a fish eye of 4H having 5 or less per 100 cm.sup.2 ;(2) wherein the ferromagnetic metal particles have (a) a saturation magnetization (.sigma.s) of 110 to 160 emu/g, and (b) a specific surface area measured by the BET method of 25 to 65 m.sup.