RELIEVING ARRANGEMENTS 289
subject to axial thrust on the part of the steam or other motive medium in one
and the same direction, while the radial turbine body &, before its entrance into
the axial turbine body a, experiences a thrust in the opposite direction at its hinder end, the force of which can, at will, be so regulated as to wholly or partially neutralize the thrust of the two turbine bodies first mentioned. For reversing turbines an
engine of this kind for forward motion and one for backward motion may be arranged to work on a common shaft. The drum bearing the pressure vanes of the
body a is enclosed by a case containing the guide vanes, and on the end presented towards the case-lid x bears a ring flange (in the illustration pointing both inwards and outwards) projecting beyond the wall of the drum. On the side
axial turbine
of the ring flange presented towards the lid x the pressure vanes of the radial turbine b are attached, while the inner side of the lid se bears the corresponding
guide vanes. Encircling the ring flange is a suitable ring-shaped extension of the case to which the entrance branch z for the motive medium is attached. / is the The steam entering through the branch z streams through the discharge branch.
Fig. 538.
radial turbine
body
b from without, but does not reach the axial
body a
until
it
has acted upon the rearward side of the radial turbine disc bearing the vanes. It is not necessary that the two turbine todies a and 6, which act together,
should do even approximately the same amount of work. For instance, the axial turbine body a can be arranged for the main work, while the radial body is, for small work, made of such dimensions that the steam acting from b to the
with full pressure on the back of the disc neutralizes the thrust forces acting in the opposite direction in the two turbines a and b, as far as may be desirable. In the relieving arrangement the size of the inner ring flange projecting over the wall
left
of the
drum
of course exerts
an
influence.
In the design of Schulz it is of importance that the high and low pressure turbines be arranged, in relation to one another, in such a manner that their axial 1 pressures act in opposite directions and wholly or partially neutralize each other. In Fig. 538 a steam turbine with axially arranged wreaths is illustrated, which 1
D. R. P. 137,792.
E. P. 8378 of the year 1901.
