Land vehicles – Wheeled – Articulated vehicle
Patent
1991-02-25
1992-12-15
Hill, Mitchell J.
Land vehicles
Wheeled
Articulated vehicle
280426, B62D 1302, B62D 5300
Patent
active
051710358
DESCRIPTION:
BRIEF SUMMARY
This invention relates to an articulated vehicle having a front sub-chassis and a rear sub-chassis, a main chassis supported by each sub-chassis for pivoting about a vertical axis, and linkage means for inter-relating the pivoting of the two sub-chassis, during turning of the vehicle, so that the angle between the median plane of one sub-chassis and the median plane of the main chassis is a function of the angle between the median plane of the other sub-chassis and the median plane of the main chassis.
Such a vehicle is disclosed in European patent application No. 83307741.5 Publication No. EP-B-0 112 712, in which the angles are maintained equal and opposite to each other by linkage means comprising crossed tension rods interconnecting the two sub-chassis and extending under the main chassis. The tension rods obstruct the underside of the main chassis and require lateral extension of the sub-chassis. An alternative linkage means comprises a sliding bearing which is carried by a transverse guide member on the main chassis and which is separately pivoted to two telescopic members extending along the median planes of the two sub-chassis. The transverse guide member obstructs the underside of the main chassis and is inconvenient to construct with sufficient strength. In both cases the ratio between the angles is fixed at unity. U.S. Pat. No. 4,735,432, corresponding to Pct/GB 85/00395, publication no. WO-A-86 01479, discloses a similar vehicle, in which the linkage means comprises a first linkage member mounted on the one sub-chassis and a second linkage member mounted on the other sub-chassis, the members being connected together by a pivot having a vertical pivot axis, the mounting of the members being such that the pivot axis is constrained to lie substantially at the intersection of the median planes of the two sub-chassis during turning. One member is fixed to the front sub-chassis and the other is movable along the median plane of the rear sub-chassis, so that the rear sub-chassis pivots through a smaller angle than the front sub-chassis during turning. In this arrangement the locus of the pivot axis is an arc of a circle centered on the pivot axis of the front sub-chassis. Thus the ratio between the angle of the front sub-chassis and the angle of the rear sub-chassis increases as the angles increase. This is disadvantageous, since ideally the ratio should be constant.
BRIEF SUMMARY OF THE INVENTION
A linkage means which enables the ratio of the angles to be controlled, preferably to be maintained substantially constant, whether or not the ratio is equal to unity.
According to the present invention, both of the members are movable along the respective median planes of the two sub-chassis, and control means act on the first linkage member so as to control the ratio between the angles by controlling the motion of the first linkage member during turning.
The control means preferably acts on a part of the first linkage member remote from the pivot axis, since the range of movement decreases with increasing distance from the pivot axis.
The control means preferably comprises mechanical guide means mounted on the main chassis. In one possible embodiment the guide means may comprise a transverse guide fixed on the main chassis and guiding a part of the first linkage member. The guide may be accurately shaped to ensure a constant ratio between the angles. However, in an embodiment preferred for simplicity of construction and adaptability of configuration, the guide means may comprise a rigid link having one end pivoted about a substantially vertical axis to the main chassis and the other end connected, directly or indirectly, to the first linkage member. When the vehicle turns, the other end of the rigid link will follow an arcuate path. By suitably selecting the position of the one end and the length of the rigid link, the motion of the first linkage member can be controlled so that the ratio between the angles is kept approximately constant. The one end is preferably pivoted at a point lying within the len
REFERENCES:
patent: 4735432 (1988-04-01), Brown
Hill Mitchell J.
Multidrive Limited
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