Extendable semi-trailer

#This invention relates to extendable semi-trailers that can be lengthened or shortened to accommodate loads of varying lengths. More particularly, the invention relates to a mechanism and structure for accommodating the conduits that contain the electrical cables and hydraulic and pneumatic hoses as the length of the trailer is varied.

#In order to supply the hydraulic or pneumatic brakes at the rear of the trailer and to provide electrical power for the required lights at the rear, the supply hoses and electrical cables must extend substantially the full length of the trailer. In semi-trailers where the trailer is a fixed length, this is not a problem, but where the length of a flat bed trailer can be varied to accommodate loads of varying lengths, the hoses and cables must be shortened and lengthened without interfering with the load. Typically, the hoses and cables must be detached and reattached, and some accommodation must be made for the extra length of the cables and hoses when the trailer is retracted. Also, these hoses and cables must be protected from damage and excessive wear, especially since failure in a brake line can be a serious safety hazard. In order to accommodate extension of the semi-trailer, the conduits containing the hoses and cables must be of sufficient length to service the rear of the semi-trailer when the trailer is fully extended, and these conduits must be supported, protected, and managed when the trailer is not extended.

#The prior art reveals attempts at solving this problem. U.S. Pat. No. 4,103,931 discloses a system in which flexible, extendable cables support extendable, coiled conduits hanging below the bed of the semi-trailer. U.S. Pat. No. 3,165,336 discloses a system utilizing a cable and pulley system attached to springs wherein the extension of the springs and the positioning of the pulleys relative to one another accommodate the extension of the semi-trailer without requiring the use of extendable conduits. Though not directed to the problem inherent in extendable semi-trailers, U.S. Pat. No. 3,494,657 discloses the use of a protective metal channel to house the conduits as they extend along the length of the trailer from front to rear. However, none of these prior art solutions provide a simple, inexpensive way of completely managing and protecting the conduit and the hoses and cables it contains regardless of the length of the trailer. There is therefore a need for an improved means for supporting, guiding and protecting the conduit when the trailer is fully or partially extended or fully retracted.

#FIG. 1 is a plan view of a portion of an extendable trailer in the extended position and showing the directionally constrained carrier in the extended position;

#FIG. 2 is a cross sectional view taken on the line 2—2 of FIG. 1 and showing the housing channel and the rear utility terminal and a cross section of the directionally constrained carrier;

#FIG. 3 is a plan view of a length of the directionally constrained carrier;

#Referring to the drawings, and particularly FIG. 1, there is shown a portion of an extendable semi-trailer having a front section 10, a rear section 12, and longitudinally extending support beams 14. The support beams 14 comprise an integral part of and are rigidly affixed to the rear section 12. The support beams 14 extend from the rear section 12 to the front section 10 where the beams 14 nest within front section 10 by slideably engaging longitudinal guide beams 17 that form a part of the front section 10. The front section 10 and the rear section 12 therefore are moveable relative to one another by allowing the support beams 14 to move telescopically within the front section 10, being guided by beams 17.

#As is well know to those skilled in the art, the front section 10 of the trailer is connectable to a prime mover or tractor (not shown) to form the semi-trailer, with the rear section 12 being suitably mounted on ground wheels (not shown).

#The support beams 14 support on their upper surfaces a channel 16 which is comprised of two spaced-apart vertical walls 18 connected at their lower ends to a bottom wall 20. Since the trailer is exposed to the elements, the bottom wall 20 contains a longitudinally extending slot 22 extending along substantially the entire length of the channel 16 so as to allow foreign material, such as debris, condensation, precipitation, etc. to escape from the channel 16.