Lorry Subframe Reinforcement via Crane Base Bolted Joints
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Solution Overview
Problem
The existing solutions for reinforcing the weakened section of a subframe on a lorry to support a loader crane are either costly and complex, requiring custom-made lateral attachment plates or complicated assembly processes, especially when the crane base and subframe need to be integrated and welded, which can be difficult and require the crane to be delivered before assembly can start.
Innovation Solution
The subframe is reinforced by forming non-yielding bolted joints between the crane base and the subframe, allowing for a stiff connection that secures the crane base to the subframe, enabling the subframe to be attached to the chassis using conventional shear-yielding connection elements, and allowing assembly to begin before the crane is delivered, with bolted joints designed for easy alignment and flexibility to accommodate different subframe widths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the subframe is reinforced by rigidly connecting it to the chassis using custom-made lateral attachment plates, then the strength of the weakened section is improved, but the device complexity and manufacturing cost increase significantly
Solution Approach 1:
The invention introduces a reinforcement element as an intermediary component that connects the subframe to the crane base. This mediator transfers and distributes the loads from the crane base across a larger area of the subframe, reinforcing the weakened section without requiring complex custom-made lateral attachment plates. The reinforcement element acts as a bridge between the subframe and crane base, spreading the stress over multiple attachment points.
Solution Approach 2:
The reinforcement solution is segmented into separate components: the subframe, the reinforcement element, and the crane base. This segmentation allows each component to be manufactured independently using standard procedures, then assembled together. The reinforcement element can be a simple plate or channel section that is easier to manufacture than custom lateral attachment plates, reducing overall device complexity.
2Strength
If the crane base and subframe are integrated as one single component and welded, then the structural strength is improved, but the ease of manufacture and assembly is worsened due to difficult-to-reach welding points
Solution Approach 1:
The invention separates the crane base and subframe into distinct components that are connected by bolting rather than welding. This segmentation allows the crane base to be manufactured and positioned independently, then attached to the subframe using bolted connections that are easily accessible from above. The reinforcement element may be welded to the subframe at accessible locations, avoiding the need for difficult-to-reach welding under the assembly.
Solution Approach 2:
The reinforcement element serves as an intermediary that provides accessible attachment points for connecting the crane base to the subframe. By positioning this element between the two main components, it creates a structure where connections can be made from accessible locations rather than requiring welding in difficult-to-reach areas underneath the assembly.
3Ease of manufacture
If the crane base is secured to the subframe using focalized bolting points, then the manufacturing simplicity is improved, but the strength and stiffness of the connection is reduced
Solution Approach 1:
The invention applies local quality by concentrating the reinforcement at the specific weakened section of the subframe where the crane base is attached. The reinforcement element is positioned locally at the front end of the subframe to provide additional strength and stiffness precisely where needed, rather than reinforcing the entire subframe uniformly. This allows the use of multiple bolting points in the critical area to achieve both simplicity and strength.
Solution Approach 2:
The reinforcement element is pre-positioned or pre-installed on the subframe before the crane base is attached. This preliminary action ensures that the reinforcement is in place to support the weakened section before the final connection is made, allowing for proper distribution of loads across multiple bolting points from the outset.
4Ease of manufacture
If the subframe is attached to the chassis using conventional shear-yielding connection elements, then the ease of assembly is improved, but the reliability of the connection under bending forces is reduced
Solution Approach 1:
The invention applies local quality by providing targeted reinforcement at the weakened section where the crane base attaches to the subframe. This local reinforcement compensates for the use of simpler shear-yielding connection elements at the chassis attachment points. The reinforcement element creates a stiffer connection locally at the critical area, maintaining reliability under bending forces even though the chassis connections remain conventional and flexible.
Data Source
Figure 1~3
Figure 4~7
Figure 8~10
AI summary
A lorry comprising: -a chassis (3); -a subframe (5), which is mounted to the chassis (3) and which has a weakened section (8) at its front end; and -a loader crane (4), which is provided with a crane base (10) mounted to the subframe (5) at the front end thereof. The crane base (10) is secured to the subframe (5) by at least a non-yielding first bolted joint (16a) and a non-yielding second bolted joint (16b) which are arranged on opposite sides of the subframe and configured to form a stiff connection between the crane base (10) and the subframe (5) so that the weakened section (8) of the subframe is reinforced by the crane base (10), wherein each one of these bolted joints (16a, 16b) comprises several bolts distributed in the longitudinal direction of the subframe (5).