Passively Steerable Module Axle for Vehicle Crane Steering Failure
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Solution Overview
Problem
Current mobile crane systems face challenges in maintaining maneuverability and controlling additional axles when the main steering circuit fails, leading to increased weight and complexity due to the need for emergency steering circuits, which are costly and weight-intensive.
Innovation Solution
A vehicle crane design with a module axle that has a preset caster angle for passive steering in case of main steering circuit failure, eliminating the need for an emergency steering circuit and incorporating an independent braking and springing system, allowing active steering through a separate hydraulic assembly electronically actuated by the main steering circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an emergency steering circuit is added to maintain maneuverability during steering circuit failure, then the reliability of the vehicle crane is improved, but the weight and complexity of the system increase
Solution Approach 1:
The module axle is designed with inherent passive steering capability through its geometric configuration (caster angle and trail), allowing it to automatically steer itself without requiring additional active steering components or emergency steering circuits. The axle body, steering knuckles, and trail arm form a self-steering mechanism that uses the vehicle's motion to automatically guide the wheels during turns.
Solution Approach 2:
Instead of adding an emergency steering circuit to actively control the axle during failures, the invention inverts the approach by designing the axle to passively steer itself through geometric properties. The passive steering is achieved through the trail arm configuration and caster angle, which automatically guide the wheels without requiring active steering input during normal or emergency conditions.
2Reliability
If an emergency steering circuit is added to maintain maneuverability during steering circuit failure, then the reliability of the vehicle crane is improved, but the weight of the vehicle crane increases
Solution Approach 1:
The module axle steers itself using its own geometric configuration rather than relying on additional steering circuits. The trail arm, steering knuckles, and caster angle create a self-steering mechanism that eliminates the need for heavy emergency steering components, pumps, and control systems while maintaining steering capability during failures.
Solution Approach 2:
The invention extracts the emergency steering function from the traditional active steering circuit and embeds it into the passive geometric configuration of the axle itself. By taking out the need for separate emergency steering components and integrating the steering capability into the axle's structural design, the overall vehicle weight is reduced while maintaining reliability.
3Device complexity
If the module axle is not coupled to the braking and steering system of the chassis, then the weight and complexity are reduced, but the braking and spring travels of the vehicle crane are worsened and the turning circle increases
Solution Approach 1:
The module axle's passive steering mechanism automatically adjusts the wheel orientation during vehicle turns using its geometric configuration, improving turning performance without requiring complex active steering integration. The self-steering capability reduces the turning circle by allowing the axle to naturally follow the vehicle's turning path.
Solution Approach 2:
The passive steering system dynamically adjusts the wheel angles during vehicle motion based on the steering input and vehicle dynamics, allowing the module axle to adapt to turning conditions without requiring active steering control. This dynamic response improves maneuverability and reduces the turning circle while maintaining system simplicity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design minimizes the weight of the module axle by avoiding the need for an emergency steering circuit, maintains maneuverability, and ensures dynamic axle load compensation, optimizing the vehicle's controllability and reducing unwanted weight and complexity.
Implementation Method 1
a steerable module axle (2) which can be releasably mounted to a rear of the chassis (5) and which has active steering with which it can be operated by means of a main steering circuit (29) of the chassis (5) of a vehicle crane (1)
Implementation Method 2
the axle (16) still continues to steer passively, purely by virtue of the caster friction caused by the caster angle (α)
Implementation Method 3
incorporating an independent braking and springing system, allowing active steering through a separate hydraulic assembly electronically actuated by the main steering circuit
Data Source
AI summary
In conventional vehicle cranes it is usually necessary in consideration of current safety regulations to provide at least two separate steering circuits for all steered axles so that, in the event of a failure of one circuit, the vehicle crane can continue to be steered by way of the other. In order to avoid that in accordance with the invention at least one steered rear axle of a vehicle crane (1) is provided with a caster (a) so that at least one axle (11-16), in the event of a steering failure, remains steerable passively by utilising the caster friction. That principle is applied in a similar manner to a module axle (2) which can be mounted to the vehicle crane (1) and which can be required for transporting additional equipment or an additional counterweight which is possibly required.