Abstract: The invention relates to an electrical contactor intended to be connected to an electrical brake warning circuit and to be mounted with sealing engagement in an orifice (5) in a rear wall (1) of a pneumatic brake booster housing divided into a front chamber (3) and a rear chamber (4) intercommunicating selectively via a piston mechanism (2) movable from a rest position near the rear wall (1), the contactor comprising a plastic body with a first body part (6) intended to be engaged into the orifice (5) in the rear wall (1) and a second body part (7) remaining outside the housing and containing at least one pair of metal electrical contacts (20, 21) actuable by way of a follower (13) equipped with a head (14) and slidably mounted in a bore (11) of the first body part (6) and stressed by a spring (19) toward the outside of the first body part, so that its head normally bears against the piston means (2) in the vicinity of its rest position, the pair of contacts comprising a stationary contact blade (20) and a mo

Abstract: The invention relates to a device for measuring the position of a movable member relative to a stationary member, the stationary member being one of the walls of a booster housing (14), and the movable member being a piston mechanism (16) dividing the housing into a front chamber and a rear chamber, comprising a movable first mechanism (42) which is movable together with the movable member (16) and the movement of which is detected in relation to a second mechanism (26) stationary relative to the stationary member (14). According to the invention, the stationary second mechanism (26) is fastened to the stationary member (14) outside the housing (14) of the booster, the movable first mechanism (42) sliding relative to the stationary second means (26), so as to vary at least one electrical quantity as a function of the position of the movable first mechanism (42) relative to the stationary second mechanism.