21. The air loss rate for a straight truck or bus with the engine off and the brakes on should not be more than:
3 psi in one minute
22. The driver must be able to see a low air pressure warning which comes on before the pressure in the service air tanks falls below ____ psi.
60
23. The braking power of the spring brakes:
Depends on the service brakes being in adjustment.
24. The air brake lag distance at 55 mph on dry pavement adds about ___ feet.
32 feet
25. Total stopping distance for air brakes is longer than that for hydraulic brakes due to ____ distance.
Brake lag