| Switch between spring and air brakes | |
| Apply the spring and air brakes together | |
| Apply the air brakes gradually | |
| Apply the spring brakes gradually |
| Are not required | |
| Must be a combination of mechanical and air brakes | |
| Must be mechanical brakes | |
| Can only be air brakes |
| Allow water and oil to be expelled from air tanks | |
| Deliver air from the air tanks to the air brakes | |
| Allow excess air pressure to be released from air tanks | |
| Deliver air from the air compressor to the air tanks |