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Gear Reprofiling |
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Penn Machine specializes in restoring the profiles
of EMD and GE bull gears. Our CBN grinding procedure
re-establishes the true involute tooth form for
proper gear contact.
Minimal stock is removed to restore the profile.
Typically, we grind in increments of .015 inches or
approximately 3% of the tooth thickness. The
reprofiled surface will have sufficient hardness and
case depth to provide additional gear life. A
maximum radius is provided below the bottom of the
gear mesh to reduced stress concentration. |
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| When to Reprofile Gears |
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It
is very important to recycle used gears by grinding
worn areas and to re-establish a true involute
profile form. Penn Machine recommends reprofiling
gear teeth to industry standards when wear exceeds
0.010 inch of tooth profile (0.020 inch of tooth
thickness at the pitch line). Gears should then be
ground just enough to restore the profile. |
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| Inspection |
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When shipping gears to Penn Machine
for reprofiling, gears should be free of any grease,
grime or crater compound. All gears are visually
inspected upon arrival for cracks in the teeth and
bore. If a visible crack is found, we will notify
you and ask for disposition. If there are no visible
cracks and if specified, we will do a magnetic
particle inspection for microscopic cracks. If
cracks are found, we will determine if they can be
removed by grinding. When cracks are too deep, we
will notify you and request disposition.
Penn Machine has the capability to remove pitting
from gear teeth, depending on the severity. When
three or more individual pits on the same tooth are
greater than 1/8 inch in diameter or 1/16 inch in
depth, we will recommend that the gear be scrapped
and request disposition. If there are three pits
together that form a pit longer than ¼ inch or
greater than 1/16 inch in depth, we will also
recommend the gear be replaced. |
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| Restoring Gears to
Specifications |
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If the bore size is out of
tolerance, we will shrink the bore back to OEM or
railroad specification to obtain required
interference. If this is not possible because of the
gear design, we will notify you and recommend that
the gear be scrapped. Bores will be honed to bring
the finish back to your specifications.
The hub face and ring diameter will be reground and
burnished to restore tolerance and proper finish. |
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| Recycled Gears |
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| Penn Machine will verify that the
gear tooth profile is correct, record tooth size and
check for tooth spacing. For traceability purposes,
all gears will be stamped with reworking information
including an ID number for the year of reprofiling,
machine ID that gear was ground on, gear’s
serialized number, grind number classification and
hub machining verification. A detailed inspection
report will be supplied with all returned reprofiled
gears and this report will be maintained for a
minimum of five years. Prior to shipment, gears will
be coated with a rust preventative that protects the
gears for a minimum of six months when stored under
cover in a conditioned environment. |
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