A latch mechanism (Mi) for a control device for high or medium voltage switchgear having at least one interrupter, the latching mechanism comprising: - a control shaft; - a first rotary member (1, 2, 3), referred to as a combined actuating, arming, and opening wheel, that is fastened to the control shaft and adapted to be set in rotation by a manual key; - a second rotary member referred to as an output and closing wheel, mounted for free rotation around the control shaft, with an output shaft being fastened to the output and closing wheel; - two spiral springs (5, 6), one of which, referred to as the opening spring, is adapted to open the interrupter of the switchgear by being released from a compressed state, the other of which, referred to as the closing spring, is adapted to close the interrupter of the switchgear by being released from a compressed state, with each of the inner ends of the opening spring and closing spring being fastened to the control shaft, while the outer end of the opening spring is fastened to the body of the mechanism and the outer end of the closing spring is fastened to the closing wheel; - closing latch means and opening latch means, both of which are mounted for pivoting movement between two states, one of which states is a state in which one said latch means is enabled to block movement of the output and closing wheel and then of the combined actuating, arming, and opening wheel (1, 2, 3), by simultaneous compression of the closing spring and opening spring, effected by rotation of the manual key in one direction, the other state permitting, in succession, the rotation of the output and closing wheel and the rotation of the combined actuating, arming, and opening wheel in the opposite direction by the release, in succession, of the closing spring and the opening spring; and - coupling means (11, 110, 111) between the manual key and the combined control, arming, and opening wheel, said coupling means being incorporated within the thickness of the combined actuating, arming, and opening wheel, and being designed for uncoupling said combined wheel (1, 2, 3) from the manual key at the end of the arming movement. - a control shaft; - a first rotary member (1, 2, 3), referred to as a combined actuating, arming, and opening wheel, that is fastened to the control shaft and adapted to be set in rotation by a manual key; - a second rotary member referred to as an output and closing wheel, mounted for free rotation around the control shaft, with an output shaft being fastened to the output and closing wheel; - two spiral springs (5, 6), one of which, referred to as the opening spring, is adapted to open the interrupter of the switchgear by being released from a compressed state, the other of which, referred to as the closing spring, is adapted to close the interrupter of the switchgear by being released from a compressed state, with each of the inner ends of the opening spring and closing spring being fastened to the control shaft, while the outer end of the opening spring is fastened to the body of the mechanism and the outer end of the closing spring is fastened to the closing wheel; - closing latch means and opening latch means, both of which are mounted for pivoting movement between two states, one of which states is a state in which one said latch means is enabled to block movement of the output and closing wheel and then of the combined actuating, arming, and opening wheel (1, 2, 3), by simultaneous compression of the closing spring and opening spring, effected by rotation of the manual key in one direction, the other state permitting, in succession, the rotation of the output and closing wheel and the rotation of the combined actuating, arming, and opening wheel in the opposite direction by the release, in succession, of the closing spring and the opening spring; and - coupling means (11, 110, 111) between the manual key and the combined control, arming, and opening wheel, said coupling means being incorporated within the thickness of the combined actuating, arming, and opening wheel, and being designed for uncoupling said combined wheel (1, 2, 3) from the manual key at the end of the arming movement.