Bogie Wheel Track Assembly for Zero-Turn Mowers
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Solution Overview
Problem
Existing track assembly systems for vehicles, such as zero-turn mowers, do not effectively distribute weight and reduce stress on axles and drivetrain components, leading to inefficiencies in traction and potential damage to surfaces.
Innovation Solution
The implementation of a bogie wheel assembly that supports all weight applied to the track, with no weight transfer through the drive wheel and axle, using a rocker with multiple bogie wheels and torsional biasing to maintain contact with the ground, and a zero-turn-radius drive system to manage torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional wheel assembly with drive wheel and axle is used, then the vehicle can achieve basic movement and traction, but the axle and drivetrain components experience excessive stress and weight concentration
Solution Approach 1:
The track assembly is divided into multiple segments including drive wheel, bogie wheels, and idler wheels that independently support different portions of the vehicle weight and provide distributed traction, reducing stress concentration on any single component
Solution Approach 2:
The design transitions from a single-point wheel contact to a distributed linear contact along the track, adding a dimensional element of length to the contact surface, which distributes the force over a larger area and reduces stress on the axle and drivetrain
2Device complexity
If a single drive wheel contacts the ground, then the vehicle structure can be simplified, but the surface being driven over suffers damage and the vehicle sinks in soft ground
Solution Approach 1:
The track extends the contact interface from a circular wheel contact patch to a continuous linear surface, dramatically increasing the area in contact with the ground and distributing the vehicle's weight to prevent surface damage and sinking
Solution Approach 2:
The track acts as a flexible continuous shell that conforms to the ground surface, providing distributed support and minimizing damage to surfaces while maintaining structural integrity through its elongated geometry
3Strength
If the bogie wheel assembly is rigidly coupled to the chassis without suspension, then the structure is simplified and more robust, but the track cannot adapt to uneven terrain
Solution Approach 1:
The bogie wheel assembly incorporates rotational freedom and suspension capability, allowing the track to dynamically adapt its configuration to uneven terrain while maintaining structural connection to the chassis through the rocker mechanism
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 configuration enhances traction, reduces damage to surfaces, and minimizes stress on axles and drivetrain components, allowing for improved performance and maneuverability on various terrains.
Implementation Method 1
The bogie wheel assembly supports all weight applied to the track such that no weight of the vehicle is supported by engagement of the drive wheel with the axle
Implementation Method 2
Torsional biasing may be employed at the pivot
Implementation Method 3
Tracks, such as are found on tanks, snowmobiles, and heavy construction equipment, provide increased surface area in contact with the ground. This results in increased traction
Data Source
AI summary
A mower includes a pair of track assemblies positioned on either side of a chassis. The track assemblies include drive wheels coupled to axles driven by an engine. A rocker rigidly mounts to the chassis independently of the engagement of the drive wheel with the axle. The rocker rotatably mounts to a mounting flange fastened to the chassis and includes a plurality of axles to which bogie wheels are mounted. The rocker is vertically below the axle and may be longitudinally centered on the axle or may be asymmetric with respect to the axle. All weight transferred is transferred to a track surrounding the drive wheel and bogie wheels through the rocker assembly engaging the chassis and no weight is transferred to the axle. A suspension may mount the track assembly to the chassis and the track may be long enough to replace front and back wheels.