Q Where can! obtain detailed information
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on the technicalities of coupling a tractive unit with a three-line braking system to a semi-trailer having a two-line system, and of coupling a tractive unit with a twoline braking system to a trailer having a three-line system ?
And can you say what the legal position is regarding these coupling exercises? All our vehicles are heavy articulated outfits registered before January 1 1968.
A The technical information you require is
given in an article "Mismatched brake couplings" (CM. February 2 1968). This is based on advice given by the Westinghouse company.
Legally it is permissible to couple a tractive unit having a three-line braking system to a trailer with a two-line system, and to couple a tractive unit with a two-line system to a trailer with a three-line layout, if the vehicle was registered before January 1968. The C and U Flegulations stipulate that vehicles registered after this date must be so equipped that at least half the wheels are braked when the secondary system is applied. The method of doing this is not given, but the Code of Practice (which details standards to which manufacturers will work) provides for the use of a three-line system.