Skid-Steer Gearbox Layout for Compact Differential Drive Packaging
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Solution Overview
Problem
Existing drive systems for skid steered vehicles, such as tracked and wheeled vehicles, face inefficiencies in packaging and maintenance access due to the need for oversized motors and complex mechanical arrangements, particularly in cross-shaft electric drive systems and differential gears.
Innovation Solution
A gearbox configuration with a controlled differential positioned between drive shafts, where steering and propulsion inputs are located on the same side of the gearbox housing, allowing for compact packaging and simplified maintenance access, and incorporating gear change units and epicyclic gear sets to optimize power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a cross-shaft electric drive system is used with mechanical regenerative arrangement, then power transmission efficiency is improved, but the assembly size increases due to the steer cross-shaft running across the vehicle outside the propulsion motor
Solution Approach 1:
The patent combines the steering and propulsion functions into a single integrated gearbox assembly. The controlled differential and gear change units are merged into one compact unit, eliminating the need for a separate cross-shaft running outside the propulsion motor. This integration maintains mechanical power transmission efficiency while reducing the overall assembly volume.
Solution Approach 2:
The patent employs a nested arrangement where the gear change units are positioned within or adjacent to the controlled differential structure. The epicyclic gear sets are integrated into the differential housing, allowing one mechanism to be nested within or alongside another, thereby reducing the overall footprint while maintaining both steering and propulsion capabilities.
2Ease of operation
If separate electric motors are used for each track (two-line system) to handle regenerative steering power, then steering control is improved, but oversized motors and power convertors are required
Solution Approach 1:
The controlled differential automatically handles the mechanical power transfer during steering operations without requiring separate electric motors for each track. The system self-regulates the power distribution between tracks through its inherent differential mechanism, eliminating the need for oversized motors and complex power conversion systems.
3Adaptability or versatility
If conventional differential gears and cross-shafts are used for skid steering, then steering capability is achieved, but the device complexity increases
Solution Approach 1:
The patent merges the differential gear mechanism and gear change units into a single integrated gearbox assembly. This consolidation reduces the number of separate components and simplifies the mechanical arrangement while maintaining full steering capability through the controlled differential's power distribution mechanism.
Solution Approach 2:
The integrated gearbox assembly performs multiple functions simultaneously: it provides differential steering control, houses gear change mechanisms, and manages power transmission to both tracks. This multi-functionality reduces overall system complexity compared to separate dedicated components for each function.
4Stability of the object's composition
If steering and propulsion inputs are located on opposite sides of the gearbox, then mechanical balance is improved, but maintenance access becomes difficult requiring access to both sides
Solution Approach 1:
The patent positions both steering and propulsion inputs on the same side of the gearbox housing, merging the access requirements for both functions into a single location. This design decision prioritizes maintenance accessibility over symmetric mechanical balance, allowing service personnel to access all critical components from one side of the vehicle.
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 minimizes the overall dimensions of the drive unit, reduces the need for oversized motors, and simplifies maintenance, while enabling efficient power transfer and steering capabilities, allowing for more motive power and reduced electrical motor sizing.
Implementation Method 1
a first gear change unit configured to receive a propulsion input from a propulsion motor and provide an output to the drive shafts; a second gear change unit configured to receive a propulsion input from a propulsion motor and provide an output to the drive shafts
Implementation Method 2
a controlled differential positioned between drive shafts and being in driveable communication with each drive shaft
Data Source
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AI summary
Gearboxes for a skid steered vehicle comprising layouts in which all electric propulsion drive motors and electric steering motors are located on one side of the gearbox, and layouts in which the drive inputs of the electric propulsion drive motors are located face to face. Gear change units and gear packaging configurations suitable for such gearboxes.