Komatsu 600-185-5120 Air Filter

The Filter That Is Not a Spare

Every second air element on a construction machine gets treated as a spare, and it is not one. The safety element sits downstream of the main element inside the same housing, and its job is to catch what gets past a torn, badly seated or over-serviced main element. On a machine working in dust, that is the difference between a filter change and an engine rebuild — which is why the housing is designed to keep it there and why Komatsu fits a double-element cleaner as standard on the PC300-8 and PC350-8.

The consequence for buying is simple: 600-185-5120 is ordered with 600-185-5110, not instead of it. A machine cannot run on the safety element alone — it is a restricted-flow backstop, not a working filter — and a service that changes the outer element while leaving a five-year-old inner one in place has kept the barrier but stopped maintaining it.

What Komatsu Does and Does Not Publish

Komatsu publishes a specification block for most of the filters on these machines: a height, a diameter, a thread, a media. For 600-185-5120 the page carries the part name Air Filter and the style Element, and no measurements. Suppliers fill that gap with their own bounding box, which is a box measurement rather than a specification, and it is how an element that is 4 mm too long gets sold as a match.

Our answer is to match it physically. The element is supplied against the 600-185-5110 it sits inside, or against the outside diameter and length of the element you take out. If those figures differ from what a supplier has told you, the physical element wins.

Ordering the Air Service as a Pair

We quote the air service for these machines as the pair — 600-185-5110 main plus 600-185-5120 safety — or as the 600-185-5100 kit after the housing has been measured, because the kit carries different published dimensions (419 × 276 × 276 mm against 405 × 282 × 282 mm) and its contents should be checked rather than assumed. The rest of the set, with Komatsu's published sizes for each number, is in the PC300-8 / PC350-8 filter set guide; the filters catalogue lists stock for the 30-tonne class.

FAQ

Q: What are the dimensions of the Komatsu 600-185-5120 filter?
A: Komatsu publishes no measurement block for 600-185-5120: its parts page gives the part name Air Filter and the style Element, and nothing else. We therefore publish no dimensions either. The element is supplied matched to the 600-185-5110 main element, and if you need a size before ordering, send the outside diameter and the length of the element you remove.

Q: Do I have to replace 600-185-5120 every time I replace the main element?
A: No. The safety element sits inside the main element and is the second barrier, so it does not see the dust load the outer element does. It is replaced when it is damaged, when it has been in service long enough to be loaded, or when the outer element has failed and let dirt past. What it must not be is cleaned and refitted repeatedly: a safety element that has been knocked out and blown off loses the media integrity you are relying on.

Q: Is 600-185-5120 included in the 600-185-5100 kit?
A: Komatsu sells 600-185-5100 as an Air Filter Kit, style Element Kit, published at 419 mm high and 276 x 276 mm in High Efficiency media. Because that kit measures differently from the 405 x 282 mm main element 600-185-5110, we do not treat the two as the same article and we do not assume the kit's contents match this pair. If you order the kit, check what is in the box against the housing before the service window closes.

Q: Can a machine run on the safety element alone?
A: No. The safety element is a restricted-flow backstop designed to protect the engine while a damaged main element is replaced, not a working filter. Running on it alone starves the engine of air and loads a small media area with the full dust stream. If the main element is torn on site and no spare is available, the machine stops until one arrives.