revolved without sliding back the latch
L{3}. To do this the pin P{4} must be withdrawn, for which purpose the
bearing cover must be removed.

In general this adjustment should not be changed except when there has
been some wear of the collars in the thrust bearing; nevertheless, it is
a wise precaution to go over the adjustment at intervals. The method of
doing this is as follows: The machine should have been in operation for
some time so as to be well and evenly heated and should be run at a
reduced speed, say 10 per cent. of the normal, during the actual
operation of making the adjustment. Adjust the upper screw which, if
tightened, would push the spindle away from the thrust bearing toward
the exhaust. Find a position for this so that when the other screw is
tightened the balance pistons can just be heard to touch, and so the
least change of position inward of the upper screw will cause the
contact to cease. To hear if the balance pistons are touching, a short
piece of hardwood should be placed against the cylinder casing near the
balance piston. If the ear is applied to the other end of the piece of
wood the contact of the balance pistons can be very easily detected. The
lower screw should then be loosened and the upper screw advanced from
five to fifteen one-thousandths, according to the machine, at which
position the latter may be considered to be set. The lower screw should
then be advanced until the under half of the thrust bearing pushes the
rotor against the other half of the thrust bearing, and from this
position it should be pushed back ten or more one-thousandths, to give
freedom for the rotor between the thrusts, and locked. A certain amount
of care should be exercised in setting the dummies, to avoid straining
the parts and thus obtain a false setting.

The object in view is to have the grooves of the balance pistons running
as close as possible to the collars in the cylinder, but without danger
of their coming in actual contact, and to allow as little freedom as
possible in the thrust bearing itself, but enough to be sure that it
will not heat. The turbine rotor itself has scarcely any end thrust, so
that all the thrust bearing has to do is to maintain the
above-prescribed adjustment.

The blades are so gaged that at all loads the rotor has a very light but
positive thrust toward the running face of the dummy strips, thus
maintaining the proper clearance at the dummies as determined by the
setting of