Shock absorbing leg with top steering attachment

Details Shock absorbing leg with top steering attachment Shock absorbing leg with top steering attachment

1999-03-23

2001-05-08

Oberleitner, Robert J. (Department: 3613)

Brakes

Internal-resistance motion retarder

Having a thrust member with a variable volume chamber

C188S322190, C267S064260

Reexamination Certificate

active

06227338

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylindrical telescoping type of shock absorber assembly for vehicles, hereinafter referred to as a shock absorbing leg, and more particularly, to a shock absorbing leg for a mobile crane and including a top steering attachment therefor. In its basic configuration, the shock absorbing leg in accordance with the subject invention comprises an outer tube securable to a vehicle frame, and a wheel carrier telescopically extensible downwards from the outer tube by a piston/cylinder unit and a steering input for the wheel carrier.
2. Description of the Prior Art
Shock absorbing legs currently in wide application, as known for example from German Patent 38 06 709 C2, include wheel carriers which are telescopically extensible downwards via a guide tube. These wheel carriers are secured to a stub axle of a wheel. A steering rod is secured as the steering input to the bottom of the shock absorbing leg, namely to the telescopically extensible wheel carrier. Steering input means are thus located at the bottom of the legs. The steering arm and steering rod for the opposite wheel must therefore also be located below the frame.
Also known from German Patent 37 43 203 C2 is a wheel location assembly likewise configured as a shock absorbing leg. This wheel location assembly includes two steering inputs, namely one in the lower portion of the wheel carrier and another one in the upper portion of the shock absorbing leg.
The drawback in prior art designs, as cited above, is that the bottom steering input along with a steering arm or steering rod secured thereto for the opposite wheel takes up considerable space below the vehicle frame. Such steering arrangements applied to the bottom portion of a shock absorbing leg reduce the space available for the frame design so that optimum design of the frame as regards its cross-sectional size, shape and location and thus, as regards its stiffness, is hampered. The shock absorbing leg as disclosed in the above referenced German Patent 37 43 203 C2 furthermore has the disadvantage that its design is made more complicated and expensive due to two steering inputs being made available, especially as regards maintaining the stability in cases where the steering forces engage two different points on the shock absorbing leg.
SUMMARY OF THE INVENTION
It is the object of the present invention, therefore, to provide a shock absorbing leg which obviates the cited drawbacks of prior art, and more particularly provides a shock absorbing leg permitting an optimum frame configuration.
These and other objects are achieved in accordance with the subject invention by the steering input for the wheel carrier being arranged solely at the top end of a shock absorbing leg, with the steering forces being transmitted to the wheel carrier through the cylinder of a piston/cylinder unit.
Accordingly, the shock absorbing leg in accordance with the invention comprises a single steering input coupler arranged at the top end of the leg. Moreover, a steering arm engaging the leg, or a steering rod for the opposite wheel which is in turn steered by the steering arm, is located above the frame over the wheel so that space is now available for extending the frame design, formerly taken up below the frame by conventional steering arrangements. The frame can thus receive an optimally enlarged cross-section so as to improve its stiffness.
Relocating the steering to the top now permits positioning the steering rods and steering arms, normally located between wheel and frame to a position above the wheels. Unlike the situation in conventional steering systems, the trapezoidal link geometry of the tie rods can now be arranged ahead of the axle, the advantage of this being that for a splayed trapezoidal link geometry the steering arms and ball heads of the steering are no longer moved into close proximity to the frame even on wheel deflection, thus making it possible to install the tie rods through tubes welded in the frame. For space reasons conventional steering arrangements require the axle steering cylinders having a large steering deflection to be arranged under the frame. By relocating the steering to the top, better possibilities now exist for joining the steering cylinders.
Yet a further advantage of the present invention is that, as regards the stability and the telescopic guidance of the wheel carrier the shock absorbing leg can now be adapted optimally to a steering input, it is no longer necessary to take into account or relocate steering forces engaging the wheel carrier from below as well as it is no longer necessary to provide a point of location for a steering rod in the lower region of the wheel carrier. With the shock absorbing leg in accordance with the invention the steering force is thus passed through the leg from an input point at the top end to the wheel carrier below, in other words the wheels are steered “through the legs”.
In one embodiment of the shock absorbing leg in accordance with the invention, the cylinder is mounted at its upper closed end on top of the outer tube by means of a radial/axial bearing, more particularly, by means of a ball bearing assembly, with the steering arm of the steering input being mounted on the cylinder preferably by a positive connection. Such a radial/axial bearing is able to accommodate the components of the wheel forces in the axial direction of the leg acting on the cylinder, and translate them via the outer tube to the frame.
In accordance with another preferred aspect the guide tube of the wheel carrier is disposed between the outer tube and the cylinder. This arrangement of the guide tube permits excellent stable location of the wheel carrier by means of the guide tube within the leg by radial forces being optimally handled without obstructing the telescopic movement of the wheel carrier. Preferably the piston rod of the piston running in the cylinder is in contact with the wheel carrier at its bottom end. The outer tube of a shock absorbing leg in accordance with the invention may comprise at its inner side several, preferably two, bearing surface regions for the outer wall of the guide tube of the wheel carrier. These bearing surface regions may be configured as plain or sliding bearings and form specifically the locations in the leg design which handle the forces occurring in the radial direction at the wheels; thus involving the “radial bearing” of the shock absorbing leg.
For transmitting the steering force from the cylinder to the guide tube in one advantageous aspect of the shock absorbing leg in accordance with the invention an axially shiftable, radial positive connection is provided between the inner side of the guide tube and the outer side of the cylinder. This connection more particularly comprises a spline. Furthermore, a bushing is provided at the open cylinder end for the piston rod so as to ensure sealing of the cylinder interior. Supply and discharge of the hydraulic fluid to and from the cylinder interior is affected in one embodiment of the present invention by a port arranged at the closed end of the cylinder, this port extending more particularly also through the steering arm positively connected to the top end of the cylinder.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.


REFERENCES:
patent: 4804198 (1989-02-01), Imai et al.
patent: 4826185 (1989-05-01), Blanchard et al.
patent: 5031732 (1991-07-01), Batek et al.
patent: 5259487 (1993-11-01), Petek
patent: 209725 (1960-06-01), None
patent: 743203 Al (1989-07-01), None
patent: 806709 A1 (1989-09-01), None
patent: 2130733 (1993-01-01), None
patent: 42

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