bricant is forced up through this hole and out between the
raised edges in a film, floating the rotating parts of the machine on a
frictionless disk of oil or water. The upper step-block has two
dowel-pins, also a key which fits into a slot across the bottom end of
the shaft.

[Illustration: FIG. 4]

The upper side of the top block is counterbored to fit the end of the
shaft. The counterbore centers the block. The dowel-pins steer the key
into the key-way across the end of the shaft, and the key compels the
block to turn with the shaft. There is also a threaded hole in the under
side of the top block. This is for the introduction of a screw which
is used to pull the top block off the end of the shaft. If taken off at
all it must be pulled, for the dowel-pins, key and counterbore are close
fits. Two long bolts with threads the whole length are used if it
becomes necessary to take down the step or other parts of the bottom of
the machine. Two of the bolts holding the cover-plate in place are
removed, these long bolts put in their places and the nuts screwed up
against the plate to hold it while the remaining bolts are removed.

How to Lower Step-Bearings to Examine Them

Now, suppose it is intended to take down the step-bearings for
examination. The first thing to do is to provide some way of holding the
shaft up in its place while we take its regular support from under it.
In some machines, inside the base, there is what is called a "jacking
ring." It is simply a loose collar on the shaft, which covers the holes
into which four plugs are screwed. These are taken out and in their
places are put four hexagonal-headed screws provided for the purpose,
which are screwed up. This brings the ring against a shoulder on the
shaft and then the cover-plate and step may be taken down.

While all the machines have the same general appearance, there are some
differences in detail which may be interesting. One difference is due to
the sub-base which is used with the oil-lubricated step-bearings. This
style of machine has the jacking ring spoken of, while others have
neither sub-base nor jacking ring, and when necessary to take down the
step a different arrangement is used.

[Illustration: FIG. 5]

A piece of iron that looks like a big horseshoe (Fig. 5) is used to hold
the shaft up. The flange that covers the entrance to the exhaust base is
taken off and a man goes in with the horseshoe-shaped shim and an
electric light. Othe