Flow control valve having a motion conversion device

The invention relates to a valve, a motion conversion device for use with a control valve and a method for operating a valve sealing member with the motion conversion device. A motion conversion device is disclosed for converting motion in one direction into motion in another direction. The motion conversion device may include a single-acting cylinder hydraulically or pneumatically coupled to a double-acting cylinder such that movement of the single-acting cylinder along an axis causes movement of the double-acting cylinder along a non-parallel axis. The single-acting cylinder may be mechanically coupled to another single-acting cylinder such that movement of one of the single-acting cylinders in a direction causes movement of the other one of the single-acting cylinders in an opposite direction. In this way, the single-acting cylinders may cooperate to provide reciprocal motion of the double-acting cylinder. Also disclosed is a valve incorporating a motion conversion device for the purpose of moving a closur