Floating Disc Brake Caliper Bushings for Low-Friction Sliding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing disc brake calipers of the floating type experience high residual torque due to friction between the cast iron caliper body and stainless steel bracket, resulting in a friction coefficient of about 0.12, which is not adequately reduced by current designs.
Innovation Solution
The introduction of bushings made of steel coated with polytetrafluoroethylene (PTFE) between the guide pin and guide seat, along with axial retention means such as inner and outer retention mechanisms, significantly reduces the friction coefficient by limiting axial sliding and preventing rotation, thereby enhancing the sliding performance between the caliper body and bracket.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sliding occurs between cast iron seat and stainless steel pin, then coupling is achieved, but friction coefficient is high (0.12)
Solution Approach 1:
A bushing is introduced as an intermediary element between the guide pin and guide seat. This bushing is made of steel coated with PTFE (polytetrafluoroethylene), which has extremely low friction properties. The bushing mediates the contact between the metal pin and seat, replacing the high-friction metal-to-metal interface with a low-friction coated surface, thereby reducing the friction coefficient from 0.12 to approximately 0.01 while maintaining the coupling function.
Solution Approach 2:
The bushing employs composite material construction by coating steel with PTFE. The steel substrate provides structural strength and rigidity, while the PTFE coating provides low-friction surface properties. This composite approach combines the advantages of both materials: the mechanical strength of steel with the lubricating properties of PTFE, achieving both reliability and low friction.
2Object-generated harmful factors
If bushing is introduced to reduce friction, then friction coefficient decreases to 0.01, but device complexity increases
Solution Approach 1:
The bushing serves as a simple intermediary component that fits into the existing guide seat and receives the guide pin. Rather than redesigning the entire coupling mechanism, the bushing is inserted as a discrete element that maintains the original pin-and-seat geometry while providing the low-friction interface. This minimizes the increase in device complexity.
Solution Approach 2:
The invention changes the surface parameter of the coupling interface by applying PTFE coating to the bushing. This parameter change (surface coating) achieves the friction reduction goal without fundamentally altering the coupling mechanism's structure. The bushing dimensions and positioning are designed to fit within the existing guide seat tolerances, minimizing structural modifications.
3Reliability
If axial retention means are added to prevent bushing sliding, then locking reliability improves, but manufacturing complexity increases
Solution Approach 1:
The axial retention means (such as shoulders, clips, or interference fits) are designed to automatically retain the bushing in its correct position during assembly. The retention feature is built into the bushing or guide seat structure, so that when the bushing is installed, it is immediately secured against axial displacement. This preliminary retention action eliminates the need for additional fastening operations.
Solution Approach 2:
The axial retention function is merged with the bushing structure itself. Rather than being a separate component, the retention feature (such as an integrated shoulder, snap-fit element, or interference-fit geometry) is combined with the bushing design. This merging reduces the total number of parts and simplifies manufacturing by eliminating separate retention components and assembly steps.
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 friction coefficient is drastically reduced to approximately 0.01, providing safer locking and improved sliding performance, while maintaining structural integrity and reducing wear.
Implementation Method 1
at least one bushing is made of steel coated with polytetrafluoroethylene (PTFE)
Implementation Method 2
The friction coefficient is drastically reduced to approximately 0.01
Data Source
Figure 1~2
Figure 3~4
AI summary
A disc brake caliper of floating type adapted to be associated with a brake disc, comprising a caliper body (14) and a bracket (16). The bracket (16) comprises means for fastening the caliper (12) to a relative support. The caliper body (14) slides in relation to the bracket (16) in an axial direction (18). The caliper (12) comprises coupling means (20) between said caliper body (14) and said bracket (16) adapted to allow the mutual relative sliding, parallel to the axial direction (18). The coupling means (20) comprise at least one guide pin (22) and at least one guide seat (24) placed respectively on said bracket (16) and said caliper body (14) or respectively on said caliper body (14) and on said bracket (16). The coupling means comprise: at least one bushing (26, 28) provided between said guide pin (22) and said guide seat (24); and axial retention means (30) for said at least one bushing (26) adapted to limit or prevent the axial sliding of said at least one bushing (26, 28) with respect to said guide seat (24).