A wet/dry vacuum or extractor that has lost its pull almost always needs a motor, not a new machine. This Ametek Lamb 116551 is the 4.8-inch two-stage 120-volt motor that sits at the heart of a long list of commercial vacuums, central vacuum power units, and floor-care equipment, and it is one of the most widely cross-referenced service motors in the industry.
Two-stage construction means two fans in series rather than one, which is what gives the motor its lift under load. That matters to the people who buy it: restoration crews pulling water, carpet cleaners running a portable extractor through a long hose, and shop owners who need a machine back on the truck rather than parked in the corner.
Use Cases
- Rebuilding commercial wet/dry vacuums that have lost lift after years of daily use
- Servicing central vacuum power units where the original motor has failed
- Keeping portable carpet extractors and box extractors in the field instead of replacing the whole unit
- Stocking a service van or shop bench with a common, high-turnover replacement motor
- Repowering custom and OEM equipment built around the 4.8-inch Lamb motor frame
Specifications
The 116551 is a 4.8-inch diameter, two-stage, 120-volt AC motor in the Ametek Lamb service range. Two-stage means the airflow passes through two fan stages in series, trading some open airflow for substantially higher sealed lift, which is why it is the standard choice in water-recovery and long-hose applications rather than in open-flow sweeping. Ametek Lamb has been building this style of motor for decades, and the frame size is one of the most commonly stocked in the aftermarket.
Dash numbers matter on Ametek motors. The 116551 family covers several variants that differ in lead style, discharge, and bearing arrangement, so before ordering, read the label on the motor already in the machine and match the full part number, the frame diameter, the number of stages, and the voltage. Confirm the mounting arrangement and the lead configuration against the old unit as well, since these are what determine whether the replacement drops straight into the housing.
Motors of this type are designed to move clean, filtered air. The single biggest thing that shortens their life is running the machine with a clogged, wet, or missing filter, which starves the motor of cooling air and cooks the windings. When you fit a new motor, fit a new filter with it, and check that the float shut-off in a wet-pickup machine is actually working. If the machine has been sparking heavily at the brushes, inspect the commutator, because a scored commutator will chew through a new set of brushes quickly.
Frequently asked questions
What does two-stage mean on a vacuum motor?
Two-stage means the air passes through two fan stages in series. This produces higher sealed lift than a comparable single-stage motor, which is why two-stage motors are used for water recovery and long-hose extraction work.
How do I confirm this motor fits my machine?
Read the label on the motor currently in the machine and match the part number, the frame diameter, the number of stages, the voltage, and the lead and discharge arrangement before ordering.
What voltage and frame size is the 116551?
It is a 120-volt AC motor in the 4.8-inch Ametek Lamb frame size.
What causes a vacuum motor like this to fail early?
Running the machine with a clogged, wet, or missing filter is the most common cause. The motor relies on clean filtered air for cooling, and starving it of that air overheats the windings.
Should I replace anything else at the same time?
Fit a fresh filter with the new motor and confirm that the float shut-off on a wet-pickup machine is working. Inspect the commutator if the old motor was sparking heavily.
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.
