A pressure plate 290 is fastened to the lower edge of each wing portion 289 so as to provide a broad surface adapted to rest on and be engaged by, a corresponding upper surface portion of a corresponding airbag 295。 Right and left airbags 295 are mounted on lift assembly 220 and are of conventional construction。 The vertical movement of rail drive assembly 135 is accomplished, in part, by pumping air into, or releasing air from, airbags 295。

Referring now to FIGS。 7-10, rail drive assembly 135 includes a first axle 325, a second axle 330, rail wheels 335, two walking beams 340, a lower pivot-plate 345, a torque reaction plate 350, an upper pivot-plate 355, two four-bar linkage assemblies 360, and a lift assembly support structure 365。 More particularly, first axle 325 and second axle 330 are positioned in transverse relation to vehicle frame 110 so as to be disposed in spaced-apart, parallel relation to one another。 Axles 325,330 are of conventional construction。

Four rail wheels 335 are disposed, one each, on the outer ends of each axle 325,330 in the manner well known in the art。 Each axle 325,330 includes a conventional axle housing 370 that is adapted to transfer rotational motive force to rail wheels 335, via a conventional gear system disposed within axle housing 370 as is well known in the art。

Drive shaft 175 is operatively coupled to axle housing 370 of first axle 325 by a conventional yoke and spline shaft slip joint 327。 Drive shaft 175 transfers rotational motive force to rail drive assembly 135 from modified reversing transmission 170。 A coupling shaft 375 is operatively mounted between the axle housings 370 of first and second axles 325, 330 so as to transfer rotational motive force to second axle 330。

Advantageously, axles 325,330 of rail drive assembly 135 may be rotated relative to vehicle frame 110, via rotation of lower pivot-plate 345, so as to allow for proper alignment of rail wheels 335 on rails 26。

Once rail drive assembly 135 has been lowered into engagement with rails 26, flip-up tag axle 125 may be lifted up out of contact with the road surface。 More particularly, flip-up tag axle 125 is first unlocked from vehicle frame 110 by removing a locking pin from locking holes 242,247 of lever-bracket 210 and pivot-bracket 215。 This releases flip-up tag axle 125 from locked engagement with vehicle frame 110。

Next, actuation cylinders 275 are energized so as to pull upon lever-arms 227 of lever-brackets 210。 This causes frame 200 to pivot in a counterclockwise manner about the pivot pin disposed within frame-pivot hole 240 and pivot hole 245。 Once rod 305 is substantially withdrawn within cylinder housing 310, flip-up tag axle 125 is fully disengaged with the road surface, as illustrated in FIG。 5。

Advantageously, use of rear wheel drive in the rail mode, via rail drive assembly 135, allows for better loading when shelf coupler 153 has a load of one or more freight or other rail cars coupled to it for pulling by vehicle 100。 More particularly, shelf coupler 153 may be powered vertically, through the inflation of airbags 295, so as to engage a corresponding coupler on an adjacent rail car in order to transfer the load from the rail car to rail wheels 335 of rail drive assembly 135。 This operation generates a resultant downward force on rails 26 by rail wheels 335, that allows for the application of sufficient tractive effort by rail wheels 335 on rails 26 for pulling/pushing heavy loads。

In order to return to the road mode, the foregoing procedure is simply reversed。 More particularly, flip-up tag axle 125 is first pivoted clockwise about the pivot pin disposed within frame-pivot hole 240 and pivot hole 245 and then locked in place。 Rail drive assembly 135 is then raised to the position shown in FIG。 4 by releasing the air from within airbags 295 and energizing lift cylinders 415。

5。Summary

In order to return to the road mode, the foregoing procedure is simply reversed。 More particularly, flip-up tag axle 125 is first pivoted clockwise about the pivot pin disposed within frame-pivot hole 240 and pivot hole 245 and then locked in place。 Rail drive assembly 135 is then raised to the position shown in FIG。 4 by releasing the air from within airbags 295 and energizing lift cylinders 415。