Understand any stock in simple English
Enter a ticker to learn what the company does and how it makes money.
Donaldson makes filters and filtration systems that clean air and liquids for engines, factories, and labs, and sells replacement filters for them.
Donaldson is a filtration company. If something has dirty air or dirty liquid that needs cleaning, there is a decent chance Donaldson makes the thing that does the cleaning. It sells air filters for truck and heavy-equipment engines, industrial dust collectors for factories, and specialized filters used in life sciences like bioprocessing and medical devices.
The business works on a simple, repeating rhythm. Donaldson sells the original filter as part of a new machine or engine, then keeps selling replacement filters for as long as that machine runs. That replacement cycle is the heart of the company: filters wear out on a schedule, so customers come back again and again. Customers pick Donaldson for the same reason people buy anything that has to work reliably in a hot, dusty, greasy place — it holds up, and it's available when they need it. Donaldson's biggest customers are equipment makers and the people who run fleets and plants. Truck and engine builders like Caterpillar, Cummins, and Deere use Donaldson filters, and their customers buy the replacements. Competitors include Parker Hannifin and Mann+Hummel, though Mann+Hummel is private. The reach is global: Donaldson sells in more than 40 countries, and about half its sales come from outside the United States.
Donaldson's real moat is boring and durable: decades of engineering know-how, a huge catalog of part numbers, and relationships with manufacturers that are hard to dislodge. It is not a fast-growing story stock; it grows modestly and throws off steady cash. It uses that cash to pay a growing dividend, buy back shares, and make acquisitions like the recent solar-energy filter deal. It is the kind of company that doesn't make headlines, but quietly keeps the world's engines and factories running clean.
Saved answer · last researched 15 Nov 2026