A switching unit for switching an electrical current, the unit comprising separable fix and mobile electrical contacts and a mechanism capable of switching over the contacts between a closed state and an open state. The mechanism comprises a switching shaft coupled to a mobile electrical contact, a trip hook mounted to be pivoted on a fixed support of the mechanism and comprising a bore in which is housed an abutment and a link system coupling the switching shaft to the trip hook. The link system comprises an articulated linkage, which is rotationally linked with respect to the trip hook and which comprises a main bearing surface, which bears on the abutment when the switching mechanism is in the closed state. The abutment is configured to be elastically deformed when the switching mechanism passes from the open state to the closed state and the linkage exerts an effect on the abutment, so as to damp the impact of the linkage on the abutment.