Flexible-Shaft Sickle Bar Mower for Lighter Safer Cutting

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Solution Overview

Problem

Sickle bar mowers are heavy, asymmetrical, and lack adequate safety features, leading to increased user workload, reduced efficiency, and a high risk of injury from mower blades encountering stones.

Innovation Solution

A sickle bar mower with a support frame and suspension, featuring flexible shafts and oscillating cutting blades, which are lightweight, efficient, and include safety mechanisms like a rotating mowing unit and shear bolts to prevent injury.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rigid drive shaft and gearbox are used to transmit power to the cutting device, then the drive mechanism is robust, but the overall weight of the mower increases significantly

Engineering Contradiction:
Improverobustness of drive mechanismVSAvoidweight of mower
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The patent replaces the traditional rigid mechanical drive system (drive shaft and gearbox) with a flexible shaft mechanism. The flexible shaft transmits rotational motion from the drive wheel to the cutting device without requiring intermediate gears or a rigid transmission system, thereby significantly reducing the overall weight of the mower while maintaining adequate drive robustness.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the gearbox component from the drive system. By using the flexible shaft directly connected to the drive wheel, the complex gear transmission mechanism is removed entirely, reducing weight and mechanical complexity while still achieving the necessary power transmission to the cutting device.

Inventive Principle:
Principle #2Taking out (Extraction)

2Stability of the object's composition

If the cutting width is reduced to accommodate the high weight design, then the structural integrity is maintained, but the mowing efficiency decreases

Engineering Contradiction:
Improvestructural integrityVSAvoidmowing efficiency
Core Design Contradiction:
Stability of the object's compositionVSProductivity

Solution Approach 1:

The patent segments the support frame into multiple components (first support frame part, second support frame part, first running shoe, second running shoe) that can be independently optimized. This segmentation allows the structure to maintain integrity while accommodating a wider cutting device, as each segment can be designed to distribute loads efficiently rather than requiring a single narrow, heavy structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent changes the structural parameters of the support frame by introducing a multi-component design with distributed weight. This allows the mower to support a wider cutting width without compromising structural integrity, as the weight is distributed across multiple frame segments and running shoes rather than concentrated in a single heavy structure.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If safety devices are added to protect against stone impacts, then user safety improves, but the device complexity and weight increase

Engineering Contradiction:
Improvesafety against injuryVSAvoidcomplexity of safety systems
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent incorporates a shear bolt mechanism as a pre-designed safety feature that automatically fails in a controlled manner when excessive force is detected (such as from stone impacts). This beforehand cushioning approach provides safety without requiring complex active sensing or control systems - the shear bolt simply breaks under overload conditions, allowing the cutting device to lift slightly and avoid damage while protecting the user.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

4Productivity

If an asymmetrical center of gravity is used in the mower design, then the cutting performance is optimized, but the ease of operation by the user deteriorates

Engineering Contradiction:
Improvecutting performanceVSAvoiduser guidance effort
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The patent deliberately uses asymmetry in the support frame design (first support frame part different from second support frame part) to optimize cutting performance while maintaining manageable operational characteristics. The asymmetrical configuration allows the cutting device to be positioned optimally for cutting efficiency, and the distributed weight across multiple frame segments helps balance the operational characteristics despite the asymmetrical center of gravity.

Inventive Principle:
Principle #4Asymmetry

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

The design results in a lightweight, efficient, and safer mower with reduced wear and improved safety through even weight distribution and collision absorption, minimizing user effort and injury risk.

Implementation Method 1

The first flexible shaft (200) extends from the suspension (112) to the first transmission unit (180). The first flexible shaft (200) is mounted in a bent state within the sickle bar mower. The first flexible shaft is, in particular, a bendable shaft that can be reversibly bent within a bending range.

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

the first transmission unit comprises an eccentric

Methodology Applied
Scientific EffectEccentric mechanism: Eccentric

Data Source

PatentEP4666830A1Bar mower with a supporting frame
Publication Date: 2025.12.24 WEPFER TECHNICS AG
  • EP4666830A1 patent drawingFigure 1
  • EP4666830A1 patent drawingFigure 2
  • EP4666830A1 patent drawingFigure 3

AI summary

A sickle bar mower comprising: - A support frame (110) with a suspension (112) for mounting the sickle bar mower (100) on a single-axle or two-axle chassis. - A first running shoe (120) and a second running shoe (130), which are connected to each other via the support frame (110). - A cutting device (160), which extends parallel to a cutter bar (150) between the first running shoe (120) and the second running shoe (130) and is designed to be oscillatingly movable by means of a first transmission unit (180), wherein the first transmission unit (180) is arranged on the first running shoe (120), and a first flexible shaft (200), which is designed to transmit a drive movement from the suspension (112) to the first transmission unit (180).