Suspended Subframe Belt Alignment for Hydrostatic ZTR Mowers
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Solution Overview
Problem
The integration of hydraulic pumps and motors in hydrostatic transaxles in ZTR mowers poses challenges in suspension of drive wheels due to variations in belt angle between drive and driven pulleys, leading to potential belt misalignment and system inoperability.
Innovation Solution
A transaxle drive system with a suspended subframe and motion-absorbing suspension components, including a compressible subframe coupled to the main frame via pivot points, and a pulley and belt drive assembly where idler pulleys and driven pulleys travel in the same plane to minimize belt angle changes and prevent misalignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If drive wheels are suspended on a ZTR mower utilizing hydrostatic transaxles, then ride comfort and terrain adaptability are improved, but belt angle variation between drive and driven pulleys increases causing belt misalignment and wear
Solution Approach 1:
A suspension component is introduced as an intermediary element between the transaxle assembly and the frame. This suspension component absorbs relative motion between the suspended transaxle assembly and the frame, thereby maintaining stable belt alignment between the drive pulley on the frame and the driven pulley on the transaxle assembly while allowing the transaxle to move independently for terrain adaptation
2Ease of operation
If drive wheels are suspended on a ZTR mower utilizing hydrostatic transaxles, then ride comfort is improved, but the drive system may become inoperable due to belt running off pulleys
Solution Approach 1:
The suspension component provides beforehand cushioning by absorbing and dampening relative motions between the transaxle assembly and the frame before these motions can cause the belt to run off the pulleys. This preventive action maintains drive system operability while allowing the transaxle to move independently for improved ride comfort
3Device complexity
If hydrostatic transaxles are integrated with belt-driven suspension, then system complexity is reduced, but belt wear increases due to angle variation
Solution Approach 1:
The suspension component acts as a mediator that decouples the motion of the transaxle assembly from the belt drive system. This allows the integrated hydrostatic transaxle design to be maintained for simplicity while the suspension component prevents excessive belt angle variation, thereby extending belt service life
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 belt misalignment and wear, ensuring the drive system remains operational and reduces the risk of belt decoupling, allowing for effective suspension and operation of ZTR mowers with hydrostatic transaxles.
Implementation Method 1
The subframe is coupled to the frame with at least one motion absorbing suspension component
Implementation Method 2
at least one motion absorbing suspension component comprises at least one of a spring and a shock absorber
Implementation Method 3
the subframe is coupled to the frame using at least one compressible component
Implementation Method 4
the at least one compressible component comprises rubber or other elastomeric polymer
Data Source
AI summary
Some embodiments include a transaxle drive system for ride-on equipment with a plurality of transaxle assemblies supported by a suspended subframe, and a frame supported on a pair of front wheels at one end that is coupled to and pivotably suspends the subframe. Some embodiments include a power source with a drive pulley supported by the frame at an opposite end. Some embodiments include a belt coupling the drive pulley to a driven pulley of the transaxle assemblies. In some embodiments, the plurality of transaxle assemblies can be driven from the drive pulley by at least a portion of the belt. Further, in some embodiments, the plurality of transaxle assemblies include a first and second transaxle assembly each coupled to a separate rear wheel. The first and second transaxle assemblies are suspended from the subframe, and can be pivoted together about the frame, and the at least one drive pulley.