This one was mentioned back in the anatomy post, but it comes up often enough in person that I figured it should get its own post.

Question(s): What are those boxes under the seats on the MAX trains? / What’s that buzzing sound?

These boxes sit above either side of the powered wheel trucks and are filled with sand. When the wheels spin or slide on slippery rail, sand is automatically deployed from these to improve traction. This is the source of the buzzing sound you will sometimes hear on the train. Sand is also released to help slow the train in emergency braking situations.

8 responses to “Sandboxes

  1. Not all the trucks, only the power trucks.

    As the cars come from the factory there is also provision for manual sand application. TriMet disables this function and repurposes the foot pedal.

  2. Jessica Bucciarelli

    I’m not much for Twitter, so let me say here that I love the rejected title for this post. (and now it’s stuck in my head) Bonus points for the double meaning of REM!

  3. Can you define “power trucks” in this context? From what I’ve seen, both “A” and “B” ends of the trains seem to have sandboxes.

    • Sure, the power trucks are those at the A & B ends that are equipped with motors. The truck under the C-section (the middle) has no motor and is unpowered. This is the case for each of the 4 types of train cars.

  4. I see. So, the Type-1’s have a C-truck even though they are single-articulated?

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