Dual Hydrostatic Tractor Drive with Single Lever Control
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Solution Overview
Problem
Existing walk-behind hand tractors face challenges with differential drive systems that lead to instability, difficulty in controlling on slopes, and require complex maintenance, while lacking independent wheel control and easy attachment deployment.
Innovation Solution
A hand tractor with dual seamless drive that independently controls left and right wheels, allowing single-handed operation and rapid attachment deployment via a self-aligning hitch with integral PTO drive shaft alignment, enabling clutchless control of speed and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If differential drive system is used, then wheel speed variation is achieved, but tractor stability and control on slopes deteriorates
Solution Approach 1:
The patent divides the drive system into two independent hydrostatic transmissions, one for each drive wheel. This segmentation eliminates the differential mechanism that causes instability, allowing each wheel to be controlled independently while maintaining tractor stability on slopes. The independent transmissions prevent the coupling of wheel motions that occurs in differential drive systems.
Solution Approach 2:
The patent employs hydrostatic transmissions using hydraulic pumps and motors to replace the mechanical differential drive system. This hydraulic approach allows for seamless speed variation and independent control of each drive wheel without the mechanical coupling that causes instability on slopes, resolving the contradiction between speed variation and stability.
2Ease of operation
If steering brakes are used to turn the tractor, then directional changes are achieved, but brake wear increases and control difficulty increases
Solution Approach 1:
The patent replaces mechanical steering brakes with a hydraulic control system that independently regulates the speed of each drive wheel through hydrostatic transmissions. This eliminates brake wear while providing smooth and reliable directional control, resolving the contradiction between ease of operation and reliability.
3Device complexity
If single transmission with differential is used, then结构简单 is achieved, but independent wheel control capability is lost
Solution Approach 1:
The patent segments the single transmission system into two independent hydrostatic transmissions, one for each drive wheel. This segmentation enables independent control of each wheel while maintaining a relatively simple overall structure through the use of modular hydrostatic units, resolving the contradiction between device complexity and adaptability.
4Measurement precision
If dual hydrostatic drive with independent control is used, then wheel control precision is improved, but device complexity increases
Solution Approach 1:
The patent uses hydrostatic transmissions with hydraulic pumps and motors to achieve precise independent control of each drive wheel. The hydraulic system provides seamless speed variation and fine control precision while keeping the overall structure manageable through modular design, resolving the contradiction between control precision and device complexity.
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 solution provides enhanced control and stability on slopes, reduces operator fatigue, and allows for quick and safe attachment changes without tools, improving traction and extending the tractor's usability in various tasks.
Implementation Method 1
Each of these transmissions has a hydrostatic pump driven by the engine and a hydrostatic motor driving a drive wheel
Implementation Method 2
These machines have vertical crankshaft motors that utilize a belt configuration in the horizontal plane that connects directly to the lawn mower
Data Source
AI summary
A tractor has a base for supporting a motive power source, left and right driven wheels, and left and right transmissions for the respective left and right wheels; a handle structure coupled to the base for grasping by an operator from behind the tractor; a drive system for driving each of the left and right transmissions with motive power from the motive power source; wherein the left and right transmissions are hydrostatic transmissions, further having a speed regulator control lever on each transmission that allows seamless control of the transmission from reverse speed through neutral into forward speed; and a transmission control coupled to each speed regulator control lever; further wherein there is a longitudinally disposed space between the left and right transmissions, and a power take off shaft is disposed in the space extending anteriorly and driven by the motive power source for powering a powered attachment arranged to be attached at the anterior of the tractor, further including a shaft extension of said power take off shaft extending posteriorly for driving a rear power take off for powering a rear mounted powered attachment.