on the spindles but because of the rotation of the rod tangential frictional or shearing contact occurs between the rod 16 and the spindles 20 and this may give rise to excessive clamping or jamming of the tap in the opening position to overcome this disadvantage the invention has proposed a novel tap one embodiment of which is illustrated by way of example in fig2 and 3 this tap is intended for opening and closing communication between two pipes 30 and 32 the tap comprises a body 34 in which is located an opening and closing member 36 co operating with a seat 38 the closing member 36 forms the lower part of a connecting rod 40 which is arranged axially in the body 34 and which is integral with an operating handwheel 42 outside the tap the upper part of the connecting rod 40 is provided with an external thread co operating with a corresponding thread in the head of the body 34 with the result that a rotation of the handwheel 42 causes the rod 40 to rise or fall depending on the direction of rotation according to the present invention the connecting rod comprises an outer radial abutment 44 whilst the body 34 comprises an inner radial counterabutment 46 the abutment 44 and the counterabutment 46 are arranged in such a way that during the rotation of the connecting rod 40 the abutment 44 passes below the counterabutment 46 at the penultimate turn in the rotation of the handwheel 42 in the opening direction.