When coupling a trailer:

Question

When coupling, make sure you couple matching glad hands. They are often color-coded to help drivers avoid mistakes. Typically, blue is used for service lines and red is used for emergency lines.

Accepted Answer

Make sure to couple matching glad hands.

Answer

Any glad hand can be connected to any other glad hand.

Answer

It is best to leave one glad hand unattached.

Answer

Only one set of glad hands should be connected.