Carbon brushes are the wear item that decides how long a vacuum motor lasts, and they are also the cheapest thing on the machine to replace. This Ametek Lamb carbon brush assembly is the service part for a very wide range of Lamb motors used in commercial vacuums, central vacuum power units, extractors, and dust collection equipment.
Service technicians buy these on a schedule rather than in a crisis, and the reason is worth understanding. A brush worn past its limit lets the metal brush holder reach the commutator, and once the commutator is scored, the repair stops being a set of brushes and becomes a motor. Changing brushes in time is the difference between a small consumable and a large one.
Use Cases
- Scheduled preventive maintenance on commercial vacuum and extractor motors
- Restoring a motor that has started sparking heavily at the brush window
- Servicing central vacuum power units that have lost power or run intermittently
- Shop and service-van stock for a common wear part across many Lamb motor models
- Rebuilding dust collection and floor-care equipment built around Ametek Lamb motors
Specifications
The assembly carries a carbon block, a metal connector, and an insulated holder, which together maintain steady electrical contact once the original brush is worn. Each carbon brush measures approximately 28mm by 11mm by 6mm. The part is cross-referenced as 333261, 33326-1, 2311480 and 833326-51, and it fits a broad list of Ametek Lamb motors including the 115737, 115750, 115792, 115757-P, 116114-00, 116146-00, 116197-00, 116207-00, 116210-50, 116210-85, 116212-00, 116212-07, 116212-08 and 116212-09 among many others. Brushes work in pairs, so plan on replacing both at once.
Knowing when to change them is the practical skill. Service guidance across the trade is to check motor brushes every couple of years and replace them when they are down to about 3/16 inch. A brush is roughly 3/4 inch long when new, so there is a long service life and then a definite limit. A slight blue spark right at the brush is normal. A large blue spark that wraps around the commutator is not, and it means the brushes need attention now.
One caution matters more than any other. The point of changing the brush early is to get it out before the holder tears into the commutator. If you pull the brushes and find the commutator is no longer smooth, do not fit new brushes and put the motor back into service, because a scored commutator will destroy them and the underlying fault is the motor itself. Excessive sparking on an old motor with a blackened, pitted commutator usually means the motor is failing rather than the brushes. Before ordering, compare the size, the connector style, and the motor part number against the brush currently fitted.
Frequently asked questions
Which motors does this carbon brush assembly fit?
It fits a broad range of Ametek Lamb motors used in vacuum cleaners, central vacuum units and dust collection systems, including the 115737, 115750, 115792, 115757-P, 116114-00, 116146-00, 116197-00, 116207-00, 116210-50, 116210-85 and 116212 series among many others.
What size is the carbon brush?
Each carbon brush measures approximately 28mm by 11mm by 6mm. Compare the size, connector style and motor part number against the brush currently fitted before ordering.
When should carbon brushes be replaced?
Check them every couple of years and replace when they are worn down to about 3/16 inch. A new brush is roughly 3/4 inch long.
Is sparking at the brushes normal?
A slight blue spark right at the brush is normal. A large spark that wraps around the commutator means the brushes need replacing, or that the motor itself is failing.
What if the commutator is not smooth?
Do not fit new brushes. A scored or pitted commutator will destroy a new set quickly, and the correct repair at that point is to replace the motor.
Do I replace one brush or both?
Both. Motors of this type use a pair of brushes and they should be replaced together so they wear evenly.
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.
