Abstract: An articulated train rake includes a plurality of longitudinally aligned cars, each having leading and trailing longitudinal ends, for each car a ball joint between the leading end of said car and the trailing end of the preceding car in the row, each car including a body, at least a bogie on which the body rests, and pivot joint means for connecting the body to the bogie. The ball joints are disposed at a vertical level lower than or equal to the pivot joint means relative to the rolling plane of the rake.

Abstract: A convertible first/second-class seat offering a given number N of seating spaces convertible into a second/first-class N-seater seat, provides N seats with N seat cushions and 2N armrests, the first/second-class convertible seat includes a device for translating at least one of the N seat cushions and at least one of the 2N armrests, the N seat cushions and the 2N armrests remaining mutually aligned, translations T obtained by the translation device allowing the seat cushions that are to be translated to be moved further apart when the second-class convertible seat is converted into a first-class seat, or allowing the seat cushions that are to be translated to be moved closer together when the first-class convertible seat is converted into a second-class seat.

Abstract: A second-class two-seater seat (1) that can be converted into a first-class single-seater seat, and vice versa. The second-class two-seater seat comprises two seats (2) two seat cushions (3) and two armrests (4). The two-seater (1) comprises elements (5) for translating at least one of the seat cushions (3) and at least one of the two armrests (4), the seat cushions (3) and the armrests (4) remaining mutually aligned. Translations of the seat cushions and the armrests are obtained by the translation element's (5), allowing the seat cushions that are to be translated and the armrests that are to be translated to be brought closer together when the second-class two-seater seat is converted into a first-class single-seater seat, or the seat cushions that are to be translated and the armrests that are to be translated to be moved further apart when the first-class single-seater seat is converted into a second-class two-seater seat.

Abstract: A regulating apparatus and a regulating method for regulating the internal pressure P.sub.i of a ventilated, closed volume subjected to variations in external pressure P.sub.e, the apparatus including at least two compensation circuits enabling the intake air flow rate q.sub.1 and the extraction air flow rate q.sub.2 to be adjusted in real time so that the difference between these two flow rates algebraically compensates for the leakage flow rate q.sub.f, and maintains the internal pressure P.sub.i inside the volume at a constant level.