Which statement about exhaust system orientation is correct?

• A. Vertical exhaust systems have longer service life and do not allow exhaust gases to drift upward into the cab or bunk.
• B. Horizontal exhaust systems are advantageous because they are not damaged by low bridges or tree branches.
• C. Vertical exhaust systems are cheaper to install.
• D. Horizontal exhaust systems reduce engine durability.

Answer: (B)

Exhaust orientation affects how the exhaust path handles external hazards and keeps fumes away from the operator. A horizontal exhaust runs out to the side at a lower height, which makes it less likely to be damaged by low-clearance obstacles such as bridges or overhanging branches that would strike something higher up. This side-mounted, low profile helps protect the exhaust system and reduces the chance of damage from those kinds of obstacles, while also keeping the outlet away from the cab area. In contrast, vertical exhausts rise higher and are more exposed to being struck by tall obstructions, so the horizontal arrangement is advantageous in environments with such hazards.