Abstract: Tunnel boring machine for reaming of a pilot tunnel (11). The machine housing (12) is provided with a projecting part in front of the boring head (13), said projecting part comprising a part (20) being fixed relative to the machine housing and a shield (19) being separable from the fixed part.This arrangement permits substantially uninterrupted excavation of the tunnel and prevents the excavated soil from becoming wedged between the boring head and the tunnel front.

Abstract: The present invention provides a process for the preparation of thamphenicol (I) from D,L-threo-1-(p-methylsulphonylphenyl)-2-aminopropane-1, 3-diol hydrochloride (V) and intermediates thereof. The process comprises conversion to a corresponding benzal compound followed by hydrolysis to D,L-threo-aminodiol.

Abstract: A tunnelling machine has a swing unit (31) that is swingable about a horizontal axis (I). The swing unit has a head (50) that rotates about an axis (II) that is transverse to said horizontal axis and passes the horizontal at a distance below the horizontal axis. The head is equipped with a plurality of disc-cutters (53-58, 63) that are arranged to have their cutting edges on an imaginary sphere with a radius of about the same length as the swing radius. Upon simultaneous upward swinging of the swing unit and rotation of the head, the cutters cut both when on the leading side of the head and when on the trailing side. No cutting occurs during the return swing stroke. When the swing unit has been returned, the machine is advanced a step which is somewhat larger than the distance between the two axes, and another upward cutting stroke can be effected.