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H3: BEARINGS
TROUBLE SOURCE
PROBABLE CAUSE
REMEDY
Bearing seized or galling
on shaft
Running dry without lubrication
Check lubrication, look for plugged suction or evidence of
flashing.
Bearing failure or bearing
seized
High temperature failure
Check pump manufacturer for bearing temperature limits
Excessive shaft wear under
rubber
Rubber bearings will swell in hydrocarbon, H.S., and high
temperature
Change bearing material
Premature bearing wear
Abrasive action
Consider conversion to water flushing on all bearings,
pressure grease or oil lubrication.
Uneven wear on bearings,
uniform wear on shaft
Pump’s non-rotating parts misaligned
Check mounting and discharge pipe connection, dirt
between column joints.
Correct misalignment, replace bearings and repair or
replace shaft.
Uniform wear on bearings
and shaft
Abrasive action
Replace parts. Consider changing materials or means of
lubrication.
Uniform wear on bearings,
uneven wear on shaft
1. Shaft run-out caused by bent shafts, shafts not butted
on couplings, dirt or grease between the shafts
2. Shaft ends not properly faced
1. Straighten shaft or replace, clean and assemble cor-
rectly.
2. Face parallel and concentric.
H4: SHAFT AND COUPLING
TROUBLE SOURCE
PROBABLE CAUSE
REMEDY
Bent shaft
Mishandling in transit or assembly
Check straightness. Correct to .005”/ft total run-out or
replace.
Shaft coupling elongated
(neck down)
1. Motor is started while pump running in reverse
2. Corrosion
3. Pipe wrench fatigue on reused couplings
4. Power being applied to shafts that are not butted in
coupling
Look for faulty check valve. Could also be momentary
power failure or improper starting timers.
Shaft coupling unscrewed
Pump started in reverse rotation
Shafts may be bent. Check shafts and couplings. Correct
rotation.
Broken shaft or coupling
1. Can be caused by same reasons listed for coupling
elongation
2. Can also be caused by bearings seized due to lack of
lubrication
3. Foreign material blocking impellers or galling wear rings
4. Metal fatigue due to vibrations
5. Improper impeller adjustment or continuous up-thrust
conditions causing impeller drag
1. Same as above
2. Same as above for bearing seizure
3. Add strainers or screens.
4. Check alignment of the pump components to eliminate
vibration.
5. See Section F (Engineering) for correction.
H5: BOWLS
TROUBLE SOURCE
PROBABLE CAUSE
REMEDY
Wear on bowl vanes
Abrasive action
Coat bowls. Upgrade material or rubber line.
