11. When driving a set of doubles it is necessary to close which shut-off valve in the last trailer.
12. If the service line comes apart while you are driving a combination vehicle but the emergency line stays together, what will happen right away?
Nothing is likely to happen until you try to apply the brakes.
13. You area about to back your tractor under a semi-trailer. The trailer is at the right height when the:
The trailer will be lifted slightly when the tractor backs under it.
14. Your emergency air line breaks or gets pulled apart while you are driving. The loss of pressure will cause the:
Emergency trailer brakes to come on.
15. If the brakes are not released when you pushed the trailer air supply valve you should:
Check air line connection.