RELIEVING ARRANGEMENTS 291
pressure of the shaft c on the thrust-bearing can, within certain limits, be altered.
Manometers attached to the turbine bodies enable the steam pressures to be read off
at any time.
1
In the design of Fullagar (Fig. 540) the working wheel is provided on the
steam discharge side with a counter-pressure disc b in order to relieve the pressure
of the steam streaming in the axial direction through the turbine. Between this
dise and the wall of the case a small space is left, which is divided by labyrinth
packings & into concentric rings e. The pressure stages of the turbine are collected
into groups of different diameters, and the annular chamber e is connected, by means
of the longitudinal channels arranged symmotrically in the shaft, with the steam
chamber in front of the group in question. This is done in such a manner that
. the innermost annular chamber c receives steam from the chamber in front of the
FEMINISra
Fig. 540.
first group through the channel f, while the outermost annular chamber e, on the
other hand, receives it from the chamber in front of the last group through the
channel g. By this arrangement it clearly becomes possible to attain effectual
relief without losses of any considerable importance being brought about at the
packings, since one of the salient points of the labyrinth packing is the prevention
of the passage of steam of a certain pressure into a neighbouring chamber in which
there is a pressure only slightly less in degree. If the shaft as assumed in
Fig. 540-be made up of separato sleeves, the longitudinal channels for leading the
steam are hollowed out of the inner surfaces of these.
For his multi-stage radial turbine Lindmark (1902) has, for the relief of the
axial pressure which is produced by reason of the increase of the sectional areas of
the central inlets for the motive medium, also made use of discs loaded by steam
and arranged to act in opposition to the axial pressure. The relieving discs or
E. P. 7184 of the year 1901. D. R. P. 152,259. S. P. 24,039.
2 Compare p. 39.
D. R. P. 152,981.
