Here is the full list of all 19 Heavy Duty Challenge: The Off-Road Truck Simulator achievements.
Finish a section with the highest possible score
Complete your first Section outside of Driving School
Complete Driving School
Complete your first Event outside of Driving School
Complete your first Championship
Buy all 12 trucks
Buy a two-axle truck
Buy a three-axle truck
Buy a four-axle truck
Fully upgrade a truck
Buy a truck upgrade
Fully reinforce a truck
Buy a truck reinforcement
Complete all Events in the same truck
End a section by crashing your truck
Win a platinum Event trophy with a two-axle truck
Win a platinum Event trophy with a three-axle truck
Win a platinum Event trophy with a four-axle truck
Win a platinum Championship trophy