Hydraulic Disk Brake Retractor System for Agricultural Tractors
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Solution Overview
Problem
Agricultural tractor brake assemblies face a compromise between running clearance for efficiency and braking performance, with small clearance causing windage issues and heat damage, and large clearance compromising manual stopping distance and time requirements.
Innovation Solution
A spring-loaded brake retractor system that uses hydraulic power to create increased running clearance between brake disks, with a brake spring providing force for near-contact engagement in power-down conditions, minimizing piston travel and oil volume required for engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If running clearance between brake disks is reduced to improve braking performance and reduce pedal throw, then braking efficiency is improved, but windage effect prevents sufficient oil flow causing heat damage and lubrication failure
Solution Approach 1:
The brake retractor system proactively creates running clearance between brake disks during normal operation before braking is needed. This preliminary action ensures oil flow paths are maintained open, preventing windage effects and heat buildup. When braking is required, the piston travels a shorter distance since the clearance is already minimized by the retractor mechanism.
Solution Approach 2:
The system dynamically adjusts the running clearance between brake disks using a hydraulically actuated retractor mechanism. The clearance is not fixed but varies based on operational needs - maintained larger during normal operation for cooling, and reduced during braking for performance. This dynamic adjustment resolves the contradiction between cooling requirements and braking efficiency.
2Loss of energy
If running clearance between brake disks is increased to reduce windage loss and improve system efficiency, then oil flow and cooling are improved, but braking stopping distance and time increase
Solution Approach 1:
The brake retractor mechanism performs preliminary action by maintaining optimal running clearance during normal operation, ensuring minimal windage loss and adequate oil flow. When braking is commanded, the system has already positioned the disks for efficient engagement, reducing the additional travel needed and minimizing stopping distance and time.
Solution Approach 2:
The system employs periodic adjustment of running clearance - maintaining larger clearance during normal rotation for efficiency, then rapidly reducing clearance when braking is required. This periodic action between two states (efficient rotation vs. effective braking) resolves the contradiction between reducing windage loss and maintaining stopping performance.
3Speed
If running clearance is minimized for fast brake engagement, then pedal throw is reduced, but oil becomes entrapped between braking surfaces causing heat generation and damage
Solution Approach 1:
The retractor system performs preliminary action by pre-positioning the brake piston and maintaining controlled running clearance before braking engagement. This ensures that when braking occurs, oil can still escape through the narrow passage while the piston is already close to the disks, achieving fast engagement without trapping oil and generating excessive heat.
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
Improves brake system efficiency by allowing increased running clearance, reducing piston travel and oil volume needed for engagement, while maintaining regulated stopping performance and preventing heat damage.
Implementation Method 1
a brake spring situated between a retaining device and the retractor piston which engages the brake piston
Implementation Method 2
a source of hydraulic fluid flowing within a narrow passage in the brake housing cavity
Implementation Method 3
pressurizing the brake piston annular passage to move the brake piston within the housing cavity in a first direction; a retractor piston cavity which can be hydraulically pressurized to move the brake piston within the housing cavity in a second direction
Implementation Method 4
at least one friction disk splined into a brake housing cavity, the at least one friction disk is engaged by a brake piston
Implementation Method 5
The oil serves to lubricate and carry heat away from the brake disks when the brakes are applied
Data Source
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AI summary
A disk brake system (10) for a hydraulic disk brake retractor system (36) that maximizes running clearance while still effectively providing for manual braking in a power-down condition. A simple spring-loaded brake retractor system (36) comprised of a brake piston (20), a brake spring (22), and a retractor shaft (14) is used.