| To convert an axle into an additional fifth wheel | |
| To couple an axle and a fifth wheel | |
| To convert a fifth wheel into a dolly | |
| To convert a fifth wheel into an additional axle |
| Close the shut off valves of both trailers | |
| Open the shut off valves of the first trailer and close the shut off valves of the second trailer | |
| Open the shut off valves of both trailers | |
| Open the shut off valves of the second trailer and close the shut off valves of the first trailer |
| They have little braking power | |
| Usually require a fifth wheel converter | |
| Often do not have spring brakes | |
| All of these are true |