When a central vacuum or a commercial extractor loses suction and the hose, bags, gaskets and filters have all been ruled out, the motor is next. The Ametek Lamb 115330 is one of the most widely used replacement motors in that situation: a 7.2-inch two-stage 120-volt unit with peripheral bypass discharge, rated at 115.7 CFM and 84.9 inches of waterlift. It is specified into central vacuum power units, extractors and industrial vacuum equipment, and it is the size and configuration most likely to be sitting in a machine that is ten years old and still worth fixing.
Use Cases
- Central vacuum power unit rebuilds. The most common home for a 7.2-inch two-stage motor, where a replacement is far cheaper than a new power unit.
- Carpet extractors and portables. Vacuum motors in extraction equipment work hard and are a routine service item.
- Commercial and industrial vacuums. Wet/dry and continuous-duty machines built around a Lamb motor of this frame size.
- OEM equipment service. Machine builders and service shops keeping the common frame sizes on the shelf.
- Bypass applications. Peripheral bypass discharge keeps the cooling air path separate from the work air, which is what makes this configuration suitable for wet pickup equipment.
How to know it is the motor
Work through the cheap causes first. A hose leak, a packed filter bag, a split gasket or a clogged inlet all produce the same complaint - the machine barely picks up. If those are clean and it still will not pull, the internal fans or the bearings are the likely fault.
Two symptoms point at the motor specifically. A burning smell means the armature is overheating or shorting; shut the machine off at once rather than running it to see what happens. A motor that cuts in and out under load usually has carbon brushes worn to the point of losing contact with the commutator - and that is worth checking before buying a motor, because brushes are a fraction of the cost. The rule of thumb is that a brush shorter than about 3/16 inch is finished. If the brushes are healthy and the motor still will not run properly, replacement is the repair.
What two stages and bypass mean here
A two-stage motor puts two fans in series, which builds a higher waterlift than a single stage of the same diameter. Waterlift is the number that matters for pulling debris up a long hose run or lifting water in an extractor, while CFM is the number that matters for moving air volume. At 84.9 inches of lift and 115.7 CFM, this motor is configured for lift rather than raw airflow, which is the correct trade for hose-based central vacuum and extraction work.
Peripheral bypass discharge means the motor cooling air is drawn separately from the work airstream and discharged around the periphery of the housing, rather than passing dirty or wet air across the motor windings. That is what allows a motor to be used in wet pickup equipment.
Specifications
- Manufacturer part number: 115330
- Brand: Ametek Lamb
- Diameter: 7.2 inches, 183 mm
- Stages: 2
- Voltage: 120 V
- Discharge: peripheral bypass
- CFM: 115.7
- Waterlift: 84.9 inches
- Air watts: 399
- Amps: 13.4
- Height: 6 inches
- Bolt height: 2.5 inches
- Bearings: double ball, permanently lubricated
- Speed: single speed
- Brackets: aluminum fan end bracket, aluminum commutator bracket
- Duty: intermittent
- Average brush life: approximately 700 hours
Distributor listings for this motor vary slightly on the current draw and air watts figures depending on the test point used. The values above are the ones on our spec sheet; if your application is close to a limit, work from the manufacturer performance curve rather than from a single headline number.
Click here to view a complete spec sheet
Frequently asked questions
Should I check the carbon brushes before buying a motor?
Yes, always. A motor that cuts in and out under load very often just has worn brushes. If a brush is shorter than roughly 3/16 inch it needs replacing, and that repair costs a fraction of a new motor.
What does a burning smell mean?
It means the armature is overheating or shorting. Switch the machine off immediately and do not keep running it - continuing risks a fire, and it will not tell you anything a bench test would not.
Will this fit my machine?
Fitment is decided by diameter, bolt height, discharge type, voltage and the electrical connections. This is a 7.2-inch two-stage 120-volt peripheral bypass motor, 6 inches high with a 2.5-inch bolt height. Compare those against the motor you are removing, and if anything does not line up, call us with the machine model before ordering.
Is 84.9 inches of waterlift good?
For hose-based work, yes. Waterlift is what pulls debris up a long hose run and what lifts water in an extractor. A single-stage motor of the same diameter would move comparable air but would not produce this lift.
What does intermittent duty mean for my machine?
It means the motor is rated for the run-and-rest cycles typical of vacuum equipment rather than continuous operation at full load. Central vacuum and extraction work falls comfortably inside that. Continuous industrial duty is a different specification.
Discount Cleaning Products stocks Ametek Lamb vacuum motors across the common frame sizes and supports the order from the United States. If you are not certain which motor is in your machine, send us the machine model or the numbers stamped on the old motor and we will match it.
