The invention relates to a carriage (2) that comprises a bearing portion (12) on which the track-laying and maintenance machine is to be mounted, which carriage can travel along the two rails of a railroad. The carriage includes a braking means (13, 17, 21) movable between a release position in which the carriage travels along the rails of the railroad, and a braking position in which the carriage cannot travel along the rails of the railroad, which braking means can be switched into the release position thereof when the track-laying and maintenance machine is positioned on the bearing portion, and switched into the braking position thereof when the track-laying and maintenance machine is withdrawn from the bearing portion. Switching of the braking means is carried out without operator intervention.