Improved Stability in a New Semi-trailer
Page 42
If you've noticed an error in this article please click here to report it so we can fix it.
ONE of the major problems to be determined in the design of articulated six-wheelers is the amount of flexibility to be provided -in the turntable mounting. A. Ferraris, Ltd., 200-220. The Broadway, Cricklewood, London, N.W.2, in producing the new Pullmore 4-5-ton semi-trailer, has tackled this problem from the point of view of improving the stability of the complete vehicle.
The trailer is rigidly mounted upon the tractor frame and by this means any twisting strain is taken by the road springs of both the tractor and trailer units, the stability, it is claimed, being equal to that of a rigid four-wheeled unit.
A further point calculated to improve the stability concerns the position of the trunnion on the turntable. In this case it is mounted on the trailer, so that its axis will always remain parallel with the trailer rear axle, and the stability of the vehicle will remain unaffected by the position of the tractor unit.
A substantial, well-braced frame carries, at its forward end, trunnions, supported from which is a tubular cross-member. Welded to the crossmember is the trailer half of the turntable, this working between two annular sliding plates rigidly mounted on the tractor chassis. Lubrication of the sliding surfaces is effected by grease nipples situated on the tractor portion of the turntable. The mounting is shown in an accompanying illustration and the substantial construction will be noted The turntable is mounted forward of the rear axle of the tractor, in. order to assist in road holding and to pro-. 'vide better weight distribution. The trailer is equipped with twin rear wheels and cable-operated brakes, a simple hand-lever mechanism enabling the brakes to be separately operated. Heavy half-elliptic springs equipped with helper leaves support the frame at the rear end, and the weight of the complete unit with a platform body comes within the 3-ton class.