Answer :
Final answer:
The 'Low Air' warning on trucks with air brakes should activate at 60 psi to alert the driver of potentially unsafe braking conditions.
Explanation:
On trucks with air brakes, the "Low Air" warning should operate at 60 psi in the primary reservoir. This means that when the air pressure in the primary reservoir drops below 60 psi, the warning system is activated to alert the driver.
This warning is critical for the safety of the vehicle as it signifies that the air pressure is approaching a dangerously low level where braking capability is compromised.
To ensure safety, drivers should be attentive to the low air warning and take immediate action to address the situation before continuing to operate the vehicle.