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Cabin door- foldable step coupling

IP.com Disclosure Number: IPCOM000033107D
Publication Date: 2004-Nov-26
Document File: 3 page(s) / 101K

Publishing Venue

The IP.com Prior Art Database

Abstract

In a foldable step of a truck, the folding movement is actuated by the movement of the cabin door of. A shaft connected to the cabin door hinge is in turn connected to a linkage that is capable of folding down the step when the door is swung open and vice versa. As the cabin is often movably suspended on the truck body, and allowed to make restricted movements in a three-dimensional floating manner relative to the truck body, a problem is to find a suitable coupling capable of absorbing these movements. According to the invention a flexible helix beam is used as a coupling between a hinge extension of the cabin door and a rotatable shaft provided for the folding and unfolding movement the foldable step. The flexible helical spring coupling is machined from one piece of material and capable of absorbing the three-dimensional movements between the cabin and body of the truck. Further, the preferred helix beam is designed with more than one helical winding to have sufficient torsional stiffness and so that adjacent turns of the windings do not contact each other during movement to avoid generation of noise.

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Cabin door- foldable step coupling

To facilitate climbing into and out of a truck cabin it is known to arrange various kinds of foldable steps below a cabin door. Thereby the steps can be more or less mutually displaced from the vertical in a staircase-like manner so that the driver/passenger may climb the steps with less strain to the arms.

In one known type of foldable step, the folding movement is actuated by the movement of the cabin door. More precisely, a shaft connected to the cabin door hinge is in turn connected to a linkage that is capable of folding down the step when the door is swung open and vice versa. As the cabin is often movably suspended on the truck body, and allowed to make restricted movements in a three-dimensional floating manner relative to the truck body, a problem is to find a suitable coupling capable of absorbing these movements.  

Further, the cabin door may also be connected to a cover hinged to the truck body for a higher level step so that the cover follows the opening and closing movements of the cabin door. Another problem then arises when the truck cabin is tiltable in relation to the truck body so that the connection between the door and the cover must be releasable. Known solutions of releasable connections, involving a projection from the door engaging a slot in the cover, have shown to be noisy when the cabin moves relative to the truck body.     

An object of the present invention is therefore to provide a solution to the problems involved in coupling a cabin door movement to a foldable step and, optionally, to a cover for a higher level step.

In a broad aspect of the invention, a flexible helix beam is used as a coupling between a hinge extension of the cabin door and a rotatable shaft provided for the folding and unfolding movement the foldable step.

A flexible helix beam, such as the HELI-CAL ® Flexure, is a flexible helical spring coupling that is machined from one piece of material and capable of absorbing the three-dimensional movements between the cabin and body of the truck. The prefer...