Vacuum motors rarely fail all at once. More often the fan goes first, and the symptom is a machine that has become loud, that vibrates through the housing, and that no longer moves the air it used to even though the motor still spins freely. This Ametek Lamb rotating fan is the replacement impeller for that failure on 114-787 and 114-789 series motors.
It is a repair part for service technicians and equipment shops, and its value is simple arithmetic: replacing a damaged impeller restores airflow on a motor that is otherwise sound, instead of scrapping a whole motor over one component. Central vacuum installers, wet/dry vacuum service shops, and blower-equipment technicians are the usual buyers.
Use Cases
- Restoring airflow on a 114-787 or 114-789 motor with a damaged or out-of-balance impeller
- Quieting a vacuum or blower that has become loud and rough through the housing
- Rebuilding a motor as part of an armature or bearing service rather than replacing the whole unit
- Service shops repairing central vacuum power units and commercial wet/dry vacuums
- Keeping older equipment in service where a complete replacement motor is hard to source
Specifications
The 31281 is a rotating impeller for Ametek Lamb vacuum and blower motors, notably the 114-787 series, and it is cross-referenced with impeller models 14786 and 14787. It is precision balanced so the motor runs smoothly and without vibration once fitted, which is the whole point of using a proper replacement rather than a generic part. The fan measures approximately 6.75 inches in outside diameter.
Replacement is straightforward on the bench: remove the old fan, install the 31281, confirm the fit is secure, and run the motor in accordance with the service guide before returning it to the machine. Because the impeller sits at the end of the armature shaft, this is also the natural moment to check the shaft bearings, since a fan that has been running out of balance will have been working the bearings hard. If the bearings are rough, service them at the same time or the new fan will be running in the same conditions that damaged the last one.
The failures that lead here are usually ingestion damage or imbalance. A machine that has swallowed a screw, a coin, or a piece of debris past a missing filter will have chipped a blade, and a chipped impeller can never be balanced again. If the motor also shows heavy sparking at the brushes or a scored commutator, address that before deciding the fan alone will fix the machine, because a fan will not solve an electrical fault. Fit filtration correctly on reassembly so the same debris path does not repeat.
Frequently asked questions
Which motors does the 31281 fan fit?
It is the rotating impeller for Ametek Lamb vacuum and blower motors in the 114-787 and 114-789 series, and it cross-references with impeller models 14786 and 14787.
What size is the impeller?
The fan measures approximately 6.75 inches in outside diameter.
Why replace the fan instead of the whole motor?
If the windings, commutator and bearings are sound, replacing a damaged impeller restores airflow for the cost of one component rather than a complete motor.
What damages a vacuum motor fan?
Ingesting debris past a missing or failed filter is the usual cause. A chipped blade throws the impeller out of balance, which produces noise, vibration and accelerated bearing wear.
Should I check anything else while the fan is off?
Check the armature shaft bearings, since a fan running out of balance works the bearings hard. Also inspect the commutator and brushes if the motor has been sparking.
Discount Cleaning Products is an authorized dealer for the brands we carry, with US-based product support from people who know this equipment. If you are unsure whether this part matches the machine you are servicing, contact us with the model and serial number and we will confirm the fitment before you order.
