Tractor Drawbar Coupling with Tool-Free Multi-Position Locking
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Solution Overview
Problem
The existing coupling arrangements for agricultural tractors require high effort and are typically reserved for workshop visits due to the need for high tightening torques when changing between various coupling positions, making convenient handling difficult.
Innovation Solution
A coupling arrangement with a drawbar that can be moved longitudinally into multiple positions and locked using a threadless securing bolt, which is guided by upper and lower sliding surfaces on a coupling carrier plate, allowing vertical forces to be directly introduced into the plate, reducing the effort required for securing and enabling easy manual adjustment without tools.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drawbar is secured using hexagonal bolts screwed to the differential housing, then the vertical forces during operation are directly transferred to the screw connection, but correspondingly high tightening torques are required making the operation difficult and requiring workshop visits
Solution Approach 1:
The drawbar is divided into two separate bar sections (first bar section and second bar section) that can be independently positioned and secured. The first bar section is secured to the differential housing while the second bar section is guided by supporting cheeks on the coupling carrier plate, allowing each section to handle specific forces and positioning requirements separately.
Solution Approach 2:
Upper and lower supporting cheeks are introduced as intermediary elements between the second bar section and the coupling carrier plate. These supporting cheeks guide the second bar section in a longitudinally movable manner and directly receive vertical forces, mediating the force transfer away from the securing elements and reducing the effort required to lock the drawbar.
2Strength
If high tightening torques are applied to the hexagonal bolts, then the drawbar is securely locked, but the actuating forces required to lock the drawbar become excessively high for convenient handling
Solution Approach 1:
The supporting cheeks act as mediators that directly receive and transfer vertical forces from the second bar section to the coupling carrier plate. This intermediary structure bypasses the need for high tightening torques on securing elements, as the supporting cheeks are designed to handle the vertical forces during operation without requiring excessive locking forces.
Solution Approach 2:
The force transfer path is segmented into two independent paths: one through the first bar section and securing elements to the differential housing, and another through the second bar section and supporting cheeks to the coupling carrier plate. This segmentation allows each path to be optimized for its specific function, with the supporting cheeks handling vertical forces without requiring high locking strengths from securing elements.
Data Source
AI summary
A coupling arrangement for an agricultural tractor includes a drawbar having a first bar section, which is mounted in a longitudinally movable manner in a holder for attachment to an underside of a differential housing of the agricultural tractor, and a second bar section, which is situated opposite the first bar section and is guided in a longitudinally movable manner within adjacent upper and lower supporting cheeks of a coupling carrier plate provided for attachment to the rear of the agricultural tractor. The drawbar is movable into a plurality of coupling positions by longitudinal movement and can be locked therein with respect to the coupling carrier plate via at least one securing element.