The Ametek Lamb 116765 is the three-stage, 5.7-inch tangential bypass motor on 120 volts, and it is the highest-lift motor in the 5.7-inch bypass range. Published at roughly 137 inches of sealed vacuum and up to 485 air watts, it is what gets specified when a machine has to keep pulling through a long hose, a restrictive wand or a loaded filter. Extractor technicians, central vacuum installers and commercial machine builders buy it as a direct replacement.
Built for
- Carpet extractors and wet recovery machines needing maximum sealed lift
- Central vacuum power units on long tubing runs with a side-discharge housing
- Commercial wet and dry vacuums on 120-volt service
- Machines with restrictive wands, crevice tools or long hose assemblies
- Replacement stock for 5.7-inch three-stage tangential bypass motors
How this motor works
Stage count is the trade-off that decides which motor belongs in a machine. Each additional fan stage buys sealed lift and costs airflow. A single-stage motor moves the most air and is right behind a short hose; a two-stage motor is the general-purpose choice; a three-stage motor is what you want when the hose run is long or the tool is restrictive and the machine has to hold vacuum against that restriction.
A bypass motor carries a separate cooling fan, so the air that cools the armature and field never mixes with the air being pulled through the machine. That separation is the whole reason bypass motors are specified for wet recovery work such as carpet extraction and autoscrubber recovery, where the airstream is carrying water, foam and cleaning solution. It also means the motor is not being cooled by whatever the operator happens to be picking up.
Tangential discharge routes cooling air out through a single side port, which lets the machine builder aim the exhaust deliberately, into a muffler, a sound baffle, or straight out of the cabinet. On extractors and compact commercial machines where the motor sits in a tight enclosure, that directed exhaust is often the difference between a motor that runs cool and one that heat-soaks.
Note the absence of thermal protection on this motor. It is published with no thermostat, which means nothing shuts it down if a blocked hose or a packed filter drives it into overheat. On a machine built around this motor, the operator and the maintenance schedule are the thermal protection, so keep filters clean and clear restrictions promptly.
Carbon brushes are the wear part on any Ametek Lamb motor, not the motor itself. Ametek's own guidance is that a set of brushes can be changed twice before the armature and the rest of the assembly need replacing, with roughly 60 percent of original life left after the first change and about 40 percent after the second. If a machine has begun surging, losing suction intermittently, or throwing sparks at the commutator, brushes are the first thing to check before condemning the motor.
The one symptom that is not a brush job is a burning smell. Technicians on carpet-cleaning and contractor forums are consistent about this: a scorched odor means the armature has overheated where the brushes ride, and the machine should be shut down at once rather than run to the end of the job. A motor that has cooked its armature is a replacement, not a repair.
The other killer is water. Extractor and wet-recovery operators point out that it is effectively impossible to never overfill a recovery tank, and that the solution being picked up often carries degreaser. Water and foam that reach the windings do damage that no brush change undoes, which is why float shut-offs and inline filters matter as much as the motor spec does.
Ametek Lamb part numbers are not interchangeable by diameter alone. Before ordering, pull the old motor and match four things: frame diameter, number of fan stages, discharge configuration and nameplate voltage. Two motors that share a body size can have completely different gasket surfaces, lead lengths and airflow paths, and a mismatch usually shows up as a motor that physically drops in but never reaches its rated suction.
Specifications
- Fan diameter: 5.7 in
- Stages: 3
- Airflow system: bypass
- Air discharge: tangential
- Voltage: 120 V, 60/50 Hz, single phase
- Rating watts: 1,500 W
- Maximum amps: 13.5 A
- Maximum air watts: 485 per the description sheet, 465 per the feature sheet
- Sealed vacuum (water lift): 137.1 in per the description sheet, 136.0 in per the feature sheet
- Airflow: 101.2 CFM at a 2-inch orifice per the description sheet, 95.0 CFM maximum per the feature sheet
- Speeds: 1
- Enclosure: open
- Motor design: universal AC/DC
- Mounting: lug type, all-angle position
- Thermal protection: none
- Insulation: Class A
- Bearings: double ball bearing
- Air seal: yes
- Double insulation: no
- Epoxy paint: no
- Maximum ambient: 40 degrees C
- Overall height: 8-1/3 in
- Mounting brackets: metal
- Duty: intermittent
Fitment
Two source sheets for this motor publish slightly different performance figures, and both are listed above rather than averaged or silently picked between: 485 versus 465 maximum air watts, 137.1 versus 136.0 inches of sealed vacuum, and 101.2 CFM at a 2-inch orifice versus 95.0 CFM maximum. The spread is small and the measurement conditions differ, but it is a real disagreement and worth knowing if you are sizing against a specification. No manufacturer machine compatibility list is published for this part number and none is claimed here. Match diameter, stage count, discharge orientation, voltage and overall height against the motor you are removing.
Frequently asked questions
Why are two different air watt figures listed?
Because two source sheets disagree, publishing 485 and 465 maximum air watts. We list both rather than pick one. The measurement conditions behind the figures are not identical.
Does this motor have thermal protection?
No. It is published with no thermostat, so nothing shuts it down on overheat. Keep filters clean and clear restrictions promptly on a machine using this motor.
How does 116765 differ from 116764?
Both are three-stage 5.7-inch bypass motors on 120 volts. 116765 uses tangential discharge through a single side port; 116764 uses peripheral discharge in a quiet bypass build. Fit is determined by the housing.
Can it be mounted on its side?
Yes. It is rated for all-angle mounting position with lug-type mounting and metal brackets.
What is the overall height?
8-1/3 inches. Three-stage motors are taller than two-stage motors of the same diameter, so confirm clearance in your machine before ordering.
Discount Cleaning Products is a United States based dealer for Ametek Lamb vacuum motors and stocks the matching carbon brush kits, gaskets and mounting hardware alongside them. Our team works with these motors every day across central vacuum systems, extractors, autoscrubbers and shop equipment, and can help you confirm frame size, stage count, discharge style and voltage against the motor already in your machine before you order.
