REVERSING GEAR 231
such a manner that they may be impinged upon from the nozzle d, say, for the
left-hand direction of rotation, while the outer parts b are by the arrangement of the
nozzle f made to produce right-hand motion.
Case arranges two pairs of concentric vane wreaths at the side of a disc. The inner wreath on the one side of the disc forms, with the outer wreath on the other, a two-stage turbine, the stages of which stand in connection with one another by means of channels which cross each other diagonally.
Fig. 595.
In general it will be possible to effect the
reversal by the turning off and on of the
organs for the admission and discharge of the steam. When, then, the cocks are
turned from the positions for forward motion to those for backward motion, the
steam in the backwards turbine will in the first place exercise a braking action like
that of an elastic buffer, before the reversal of the direction of motion takes place.
The duration of this transition period depends in the main upon the magnitudes of
the rotating masses the kinetic energy of which has to be overcome. But the
steam just cut off continues to act until its expansion is complete, and accordingly
to some extent also delays the change of motion. Windhausen (1903) had the
idea of weakening the influence of the last factor in the following manner: The
steam, which at the time of reversing or throwing ont of gear still remains in the
working chambers of the turbine that is to be reversed or laid off in all the stages,
is led from each of these latter direct to the exhaust pipe or to the condenser.
For this purpose the working chambers, from the first to the last of the stages of
the multi-stage turbine, are connected with the exhaust pipe or with the condenser
by means of suitable pipes fitted with checking appliances.
› E. P. 8986 of the year 1903.
D. R. P. 151,880.
