Manitoba Airbrake Practice Exam

It is important to regularly check and maintain the air pressure in vehicles like straight trucks, tractors, and buses as it affects the overall performance and safety on the road. The acceptable air loss within one minute is a maximum of 3 psi. Any loss beyond that can lead to difficulties in operating the vehicle and can be hazardous. Option A, 1 psi, is too low and may indicate a larger problem with the vehicle's air system. Option B, 2 psi, is slightly low but could be a cause for concern if it continues to drop. Option D, 4 psi, is too high and could indicate a potential issue with the air system. Therefore, C is the best answer as it falls within the acceptable range of air loss.