Interpretation ID: nht74-2.14

DATE: 09/30/74

FROM: R. B. Dyson; NHTSA

TO: Royal Industries

TITLE: FMVSS INTERPRETATION

TEXT: This responds to your August 28, 1974, question whether a "logging pole trailer", which consists of a beam to which an exle-mounted bolster can be clamped at different points to accommodate different log lengths, qualifies as a heavy hauler trailer as that term is defined in Standard No. 121, Air brake systems:

"Heavy hauler trailer" means a trailer with one or more of the following characteristics:

(1) its brake lines are designed to adapt to separation or extension of the vehicle frame; or

(2) Its body consists only of a platform whose primary cargo-carrying surface is not more than 40 inches above the ground in an unloaded condition, except that it may include sides that are designed to be easily removable and a permanent "front-end structure" as that term is used in @@393.106 of this title.

The logging pole trailer you describe is a heavy hauler trailer, and as such, Standard No. 121 does not apply to this trailer until September 1, 1976. The beam or "reach", together with the bolster, constitutes the frame of the trailer, and the brake lines are designed to adapt to extension of the bolster element along the beam.