Compound Steering Mechanism for Tractor Axle Maneuverability

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Solution Overview

Problem

Conventional steering systems in agricultural vehicles with large steerable wheels face limitations in maneuverability due to a small radius of turn, which restricts movement in tight spaces and increases the area flattened during turns, especially with larger tractor sizes and implements.

Innovation Solution

A front axle mounting assembly with a steerable axle that uses a pair of support arms and a crosslink member to increase the effective pivot radius, allowing greater sideways movement and integration of axle sluing means to enhance angular and transverse displacement, facilitated by a dual-acting hydraulic ram or struts for steering and sideways motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional steering systems with single support arm are used, then device complexity is reduced, but the radius of turn is too large and maneuverability is limited

Engineering Contradiction:
ImprovemaneuverabilityVSAvoidsteering mechanism complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The steering mechanism is segmented into multiple independent components: a first support arm pivotally connected to the chassis, a second support arm pivotally connected to the first support arm, and a steerable axle connected to the second support arm. This segmentation allows each component to move independently, enabling the axle to achieve both angular displacement and transverse displacement, thereby reducing the turning radius and improving maneuverability while maintaining manageable complexity through modular design

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention adds another dimension of movement by introducing the second support arm that provides transverse displacement in addition to the angular displacement provided by the first support arm. This dimensional change transforms the steering motion from a single-plane rotation to a compound motion involving both rotation and lateral movement, significantly reducing the effective turning radius

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Length of moving object

If larger steerable wheels are used on conventional steering systems, then the tractor size increases, but the turning radius becomes even larger and the wheels may catch on the engine compartment

Engineering Contradiction:
Improvewheel sizeVSAvoidturning capability
Core Design Contradiction:
Length of moving objectVSEase of operation

Solution Approach 1:

The compound support arm mechanism introduces transverse displacement as an additional degree of freedom, allowing the axle and wheels to move laterally relative to the chassis in addition to rotating. This dimensional change enables larger wheels to turn without their inner edges catching on the engine compartment or frame, as the entire axle assembly shifts sideways during the turning motion

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The system transitions from a static, fixed-geometry steering arrangement to a dynamic system where the support arms can pivot and adjust the axle position. This dynamic capability allows the wheel path to be optimized during turning, preventing the wheels from contacting the engine compartment while accommodating larger wheel sizes

Inventive Principle:
Principle #15Dynamics

3Device complexity

If the axle pivot radius is small, then the steering mechanism is simpler, but the maximum pivot angle is inhibited and the inner wheel comes closer to the vehicle frame

Engineering Contradiction:
Improvepivot mechanism complexityVSAvoidpivot angle range
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The pivot mechanism is segmented into two sequential pivot points: the first support arm pivots relative to the chassis, and the second support arm pivots relative to the first support arm. This segmentation of the pivoting function allows the system to achieve a larger effective pivot angle and greater transverse displacement without requiring an overly complex single-point pivot mechanism

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The compound support arm mechanism provides more transverse displacement and pivot angle than a simple single-arm system, achieving excessive action in terms of movement range. This partial over-engineering of the displacement capability ensures that the inner wheel maintains sufficient clearance from the vehicle frame even at maximum steering angles

Inventive Principle:
Principle #16Partial or excessive action

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 significantly increases the maximum pivot angle and distance between the inner wheel and the vehicle frame, enabling larger wheels and reduced turning radius, improving maneuverability and minimizing area flattening during turns.

Implementation Method 1

The rear part of the axle 20 is connected to the support through a further ball-and-socket joint allowing the axle to pivot in an arc about this joint

Methodology Applied
Scientific EffectSpherical joint rotation: Ball

Implementation Method 2

a dual-acting hydraulic ram or struts for steering and sideways motion

Methodology Applied
Scientific EffectHydraulic force: Hydraulic Press

Data Source

PatentEP2229288B1Compound steering mechanism
Publication Date: 2011.04.27 AGCO SA (FR)
  • EP2229288B1 patent drawingFigure 1~2
  • EP2229288B1 patent drawingFigure 3
  • EP2229288B1 patent drawingFigure 4

AI summary

In summary, there is provided a front axle mounting assembly (100) which is suitable for a tractor or a construction vehicle for example. The assembly comprises a steerable front axle (130), which is typically the front axle on a tractor, and a pair of support arms (120) which extend forwardly from the main body of the vehicle. The arms are pivotally mounted to the body of the vehicle, for example, at the front of the chassis, at transversely spaced mounting points (121). The other ends of the arms (120) are pivotally attached to, and maintained at a fixed spacing, by a crosslink member (124). The axle (130) is mounted to the crosslink member (124) so as to be parallel thereto when viewed from above. By mounting the axle (130) on two support arms (120) instead of one, the effective radius of pivot of the axle is significantly increased, thereby allowing the axle to move sideways to a greater extent for a given angular displacement.