is mounted on the regulatable eccentric 17 this connecting rod 19 is pivotally connected to a lever 20 which in turn is pivotally connected to one end of a link 21 the opposite end of link 21 is pivotally connected at 22 to the feed dog support bar 13 the latter completes the aforementioned longitudinal alternating movement in that it is displaced by a block 23 which is slidably disposed in a groove 24 provided in the feed dog support bar per se and which is pivotable on a pin 25 that is supported by the opposed walls 26 and 27 of the base 2 the alternating lifting movement is produced by an eccentric 28 which is fixed on the rotating shaft 18 and to which one end of a connecting rod 29 is operatively attached the opposite end of this connecting rod 29 is pivotally connected to that end of the feed dog support 13 identified by numeral 30 the latter completes the alternating lifting movement by rotating about the pin 25 that is supported by the aforementioned block 23 in the base 2 a control shaft 31 for the conventional hooks of the lower sewing elements not shown is provided and is located beneath the feed dog support bar 13 the feed dog support bar 13 projects from the chamber 32 provided in the base 2 beneath the work surface 33 which hermetically seals this chamber which was cast as a unitary member to prevent lubricant from escaping from the.