| They have little braking power | |
| Usually require a fifth wheel converter | |
| Often do not have spring brakes | |
| All of these are true |
| The minimum air pressure for the air storage tanks | |
| The average air pressure maintained in 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 |
| In the middle of the jackknife | |
| When you start to recover from the jackknife | |
| Never | |
| As soon as you start to jackknife |