A directionally sensitive control mechanism for a friction engaging device, for example a brake mechanism, adapted to be used in an automatic transmission wherein automatic ratio changes are to be made. The directionally sensitive control mechanism comprises an hydraulic motor having a piston with a fluid chamber on one side thereof which is adapted to engage the friction device. The control mechanism includes a lever and ball mounted in a pocket in the piston on the opposite side thereof from said chamber. The ball is in contact with a rotatable friction plate of the device and with said lever, said lever being in contact with said check valve; whereby when the piston moves to engage the friction device, in one direction of relative rotation between said plate and said piston, said ball will hold said lever in a position to keep open said check valve so that the brake cannot be fully engaged until the direction of relative rotation reverses.
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