This achievement requires the player to deliver one of each Heavy Cargo Pack DLC freights.
These jobs require a truck that's capable of hauling such heavy loads. Taking a quick job will always result in trucks that can handle it, but your own truck may need to be modified. The best truck for these jobs imho seems to be the Volvo FH16 Classic. Fully upgraded, that thing's a beast.
In the job screen you can add filters. If you choose the filter on the weight you'll probably get the heavy cargo jobs first.
The freights needed are:
Asphalt Miller, Industrial Cable Reel, Concrete Beams, Crawl Dozer, Locomotive, Metal Centering, Mobile Crane, Transformer
After you delivered at least one of all eight cargo types, you get the achievement.