The Truck You Don't Want Behind You

If a milk truck stops behind you at a red light, hope it's full. A full tank can't slosh, but a milk truck fills up farm by farm, so it often rides half empty. When it brakes, the milk keeps going: the wave slams into the front of the tank and can shove the whole stopped truck forward. Fuel tankers break that wave up with baffles, walls inside the tank full of holes. In the US, a milk tanker isn't allowed a single one: sanitation rules forbid them, because they can't be scrubbed clean. (Some countries' dairy tankers do have baffles.) Sources: US model CDL manual, Section 8, Tank Vehicles (Oregon DMV edition: §8.2.2 ‘Danger of Surge’, §8.2.4 ‘Baffled Tanks’, §8.2.5 ‘Un-Baffled Tanks’) · NTI, ‘Dairy Tanker Basics’ (Australia) #trucks #physics #milk #engineering