Land vehicles – Wheeled – Articulated vehicle
Patent
1990-11-08
1993-05-04
Hill, Mitchell J.
Land vehicles
Wheeled
Articulated vehicle
280 816, 280 98, 280432, 280442, B62D 1302, B62D 1306
Patent
active
052074439
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a multiple axle trailer and particularly to the steerage thereof.
In order to minimize wear and tear on tyres and chassis stress it is advantageous that the trailer wheels properly follow the wheels of the towing vehicle, be it lorry cab or tractor. To achieve this it is usually necessary that successive pairs of wheels take up slightly different positions and angles under the chassis.
Existing steering systems for trailers use the bogie system for steering by means of which both wheels of a pair are turned simultaneously by altering the angle of the axle which connects the wheels together or allowing the rear axle wheels to pivot.
SUMMARY OF THE INVENTION
According to the present invention there is provided a multiple axle trailer comprising
a sub-chassis fitted with at least first and second axles, a chassis supported on the sub-chassis to pivot relative to the sub-chassis and provided with means at its forward end to enable the trailer to be pivoted to a towing vehicle, a pair of wheels on the first axle able to turn with respect to the first axle,
characterized in that there is provided
a steering arm pivotally connected to the sub-chassis at a first pivot, and to the chassis at a second pivot, and adapted to pivot relative to the sub-chassis when the chassis is caused to pivot relative to the sub-chassis, the length of the steering arm being adjustable to cater to changes in the distance between the first and second pivots during operation;
a mounting point movable with the steering arm,
a respective pivot point associated with each of the first wheels,
and a system of linkages connected between each of the wheel pivot points and the mounting point, the linkages being operable to steer the wheels of the first axle in response to the pivotal position of the steering arm relative to the sub-chassis.
The actual path taken by the trailer will depend on the geometry of the steering arms.
Thus rather than taking the line of least resistance, as was the case in the prior art, the steered wheels are actively brought to the optimum position for following the towing vehicle.
Advantageously the sub-chassis comprises the lower part of a turntable and the chassis includes the upper part of the turn table, the pivot point connecting the two parts of the turntable being located substantially centrally over the axles.
The linkages may include a track arm and a track rod for each wheel of the first pair, each track rod having a first end pivotally mounted to the said mounting point and a second end pivotally mounted to its respective track arm.
Preferably the lower part of the turntable is in the form of a square or rhombus with two opposed corners directed longitudinally of the trailer.
In one embodiment the mounting point is moveable longitudinally of the steering arm between a position in front of an imaginary line joining the track rod second ends and a position behind the said imaginary line.
The adjustment of the position of the track rod mounting points in this way alters the direction that the wheels will turn in response to an angular movement of the steering arm. For forward motion the front wheels will be turned to track the towing vehicle while for the same angular movement when the vehicle is in reverse the wheels will be turned the opposite way to steer the towing vehicle making reversing as easy as a fixed axle.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described by way of example with reference to the accompanying drawings in which:
FIG. 1 is a diagrammatic side view partially in section of a trailer according to the invention with the chassis lifted off the sub-chassis to show the connection,
FIG. 2 is a diagrammatic plan view of the sub-chassis of the trailer of FIG. 1,
FIG. 3 is a diagrammatic longitudinal section of the sub-chassis of FIG. 1,
FIG. 4 is a diagrammatic front view of the sub-chassis of FIG. 1 showing the arrangement of linkages,
FIG. 5 is a diagrammatic side view of a second embodiment of the inventi
REFERENCES:
patent: 3291503 (1966-12-01), DeLay
patent: 3448999 (1969-06-01), Kollander et al.
patent: 4369983 (1983-01-01), Charek
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