The table can be power driven to provide travel
6. Be sure the actual shaft size has not been
modified from the blueprint.
perpendicular to the spindle. This makes it possible
to bore, elongate, and slot when you use the table in
After you have completed these steps, send the
conjunction with vertical movement of the head.
bearing to the foundry to be rebabbitted. When you
receive the rebabbitted bearing from the foundry,
You can use a horizontal boring mill to line bore a
rough machine the bearing on a shaper to remove the
split casing pump. You can use a standard boring bar,
excess babbitt extending above the horizontal flanges.
but it is preferable to manufacture dummy bearings
Be extremely careful that you do not damage the base
and install them in the pump's bearing housings.
metal of the horizontal flanges during this operation.
After you have installed the dummy bearings, you
After rough machining, blue the remaining excess
will manufacture a boring bar to fit the bearings. You
babbitt and scrape it until no more excess babbitt
will then modify a tapered shank that fits the boring
extends above the horizontal flanges.
machine spindle so you can have a universal joint
welded to it. The other end of the universal joint will
Next, assemble the two half-shells and set them
be modified to accept the boring bar. By using a
up on the horizontal boring mill. Check the spherical
universal joint, the tapered shank will drive the boring
diameter of the bearing to ensure that it is not
bar without the pump being in perfect alignment. This
distorted beyond blueprint specifications. Generally,
is a long and complicated job, and it is best to consult
the words "BORE TRUE TO THIS SURFACE" are
with someone that has done it before you attempt it.
inscribed on the front face of the bearing shell. When
you dial in the bearing, be sure to dial in on this
Reconditioning Split-Sleeve Bearings
When you have aligned the bearing in the boring
Practically all of the high-speed bearings the
mill, you can complete practically all the other
Navy uses on turbines are the babbitt-lined
operations without changing the setup. Bore the
split-sleeve type. Once a bearing of this type has
bearing to the finished diameter and machine the oil
wiped, it must be reconditioned at the first
grooves as required by blueprint specifications.
opportunity. Wiped means the bearing has been
Figure 8-13 shows a line shaft bearing that has had the
damaged by an abnormal condition, such as
"cheeks" or oil reservoir grooves cut into it
insufficient lubrication. If it has wiped only slightly,
Oil is distributed through the bearing by oil
it can probably be scraped to a good bearing surface
grooves. These grooves may be of several forms; the
and restored to service. If it is badly wiped, it will
two simplest are axial and circumferential.
have to be rebabbitted and rebored, or possibly
Sometimes circumferential grooves are placed at the
replaced. When you receive a wiped bearing for
ends of the bearings as a controlling device to prevent
repair, use the following procedure and follow it as
side leakage, but this type of grooving does not affect
closely as possible:
the distribution of lubricant.
1. Check the extent of damage and wear marks.
When you machine grooves into a bearing, you
2. Take photos of the bearing to show the actual
must be careful in beveling the groove out into the
condition of the bearing and for future
bearing leads to prevent excess babbitt from clogging
reference during machining and reassembly.
the oil passage. The type of grooves used in a bearing
will not be changed from the original design.
3. Check the shell halves for markings. A letter
or number should be on each half for proper
When all machining is complete, both the repair
identification and assembly. (If the shell
activity and the ship's force determine that the bearing
halves are not marked, mark them before you
meets blueprint specifications and has a good bond
disassemble the bearing.)
between the shell and the babbitt metal.
4. Inspect the outer shell for burrs, worn ends,
and the condition of alignment pins and holes.
5. Check the blueprint and job order to be sure
You can cut threads on horizontal boring mills
that have a thread lead arrangement. On some
the required information has been provided to
machines, a thread lead arrangement is available with