Polarized gladhands on a tractor
- cannot be connected to trailers built before 1975.
- can be incorrectly connected to non-polarized trailer couplers. ✓
- can be incorrectly connected to polarized trailer couplers.
- cannot be incorrectly connected to non-polarized trailer couplers.
Answer: B. can be incorrectly connected to non-polarized trailer couplers.
Polarized gladhands on a tractor can be incorrectly connected to non-polarized trailer couplers.
Why this is the answer
The handbook explains that the supply and service couplers look much alike, so cross-connection is possible. Most couplers are designed to fit only their matching coupler, but some have no feature to prevent cross-connection. A polarized gladhand has the matching feature; it can still be wrongly joined to a trailer coupler that lacks that feature. That is why the bank answer points to non-polarized trailer couplers as the place where incorrect connection can happen.
Why the other answers are wrong
- A. cannot be connected to trailers built before 1975. — The passages say nothing about trailers built before 1975, so there is no basis for that date-based limit.
- C. can be incorrectly connected to polarized trailer couplers. — Polarized trailer couplers are designed to fit only the matching coupler, which is meant to prevent incorrect cross-connection.
- D. cannot be incorrectly connected to non-polarized trailer couplers. — The handbook says some couplers have no features to prevent cross-connection, so a wrong connection to a non-polarized coupler is possible rather than impossible.
Remember it
Match the colours and check the fit: if a coupler accepts the wrong line, it is not protecting you from a cross-connection.