| Cannot be used | |
| Can be used indefinitely | |
| Can still be used several times | |
| Immediately fail |
| Must be mechanical brakes | |
| Must be a combination of mechanical and air brakes | |
| Are not required | |
| Can only be air brakes |
| The average air pressure maintained in the air storage tanks | |
| The minimum air pressure for the air storage tanks | |
| The level at which the air compressor will start pumping air into the air storage tanks | |
| The level at which the air compressor will stop pumping air into the air storage tanks |