Spring Brake Release Mechanism Using a Locking Ball Connection

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Solution Overview

Problem

Existing brake release mechanisms for spring brake actuators face durability issues due to the destruction of small locking pins under high sheer forces, necessitating a more robust and cost-effective connection between the interface nut and operating section.

Innovation Solution

The use of a locking ball, preferably a ball bearing ball, configured as a press-fit connection between the interface nut and operating section, ensuring durability and ease of assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the dimensions of interface nut and locking pin are reduced to decrease overall actuator size, then the compactness of the brake release mechanism is improved, but the locking pin may be destroyed under high sheer forces during operation

Engineering Contradiction:
Improveoverall actuator sizeVSAvoiddurability of locking connection
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The locking element is designed as a spherical locking ball instead of a cylindrical locking pin. This spherical geometry allows the locking ball to be inserted at an angle into the bore formed by the interface nut and operating section, enabling easier assembly while the spherical shape distributes shear forces more effectively across the locking interface, preventing destruction under high loads

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Ease of manufacture

If a locking pin is used to block the interface nut to the operating section, then the connection is established, but the locking pin is subject to high sheer forces and may be destroyed

Engineering Contradiction:
Improveassembly convenienceVSAvoidresistance to sheer forces
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The spherical locking ball geometry enables insertion at an angle into the bore, making assembly more convenient compared to a cylindrical pin that requires precise alignment. The spherical shape also allows the locking ball to withstand high sheer forces by distributing the load across its curved surface, preventing destruction under operational loads

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Productivity

If smaller locking pins are used to match reduced interface nut dimensions, then cost and size are reduced, but the locking pin durability under high sheer forces deteriorates

Engineering Contradiction:
Improvecost-effectivenessVSAvoidlocking element durability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The spherical locking ball provides superior strength-to-size ratio compared to cylindrical pins. The curved geometry allows for more efficient force distribution, enabling the use of smaller dimensional locking elements that can still withstand high sheer forces, thereby maintaining cost-effectiveness while improving durability

Inventive Principle:
Principle #14Spheroidality (Curvature)

Data Source

PatentEP4279349B1Brake release mechanism for a spring brake actuator and corresponding spring brake actuator
Publication Date: 2026.03.18 ZF CV SYST EURO BV
  • EP4279349B1 patent drawingFigure 1
  • EP4279349B1 patent drawingFigure 2
  • EP4279349B1 patent drawingFigure 3

AI summary

The invention relates to a brake release mechanism (24) for a spring brake actuator (2), in particular a parking or emergency spring brake actuator (2) for use in a commercial vehicle, said release mechanism (24) comprising a brake release bolt (30) having a threaded portion (34) and an operating section (14) for operating the brake release bolt (30) when inserted into a spring brake actuator (2), a running nut (12) engaging the threaded portion (34), said running nut (12) being adapted to axially travel along the threaded portion (34) in order to move a spring brake actuator piston (8) against a force of an actuator power spring (6), an interface nut (22) attached to said operating section (14) of the brake release bolt (30), wherein the interface nut (22) and the operating section (14) each comprise at least one bore section (36a, 36b) that form a common bore (38) when the interface nut (22) is attached to said operating section (14), and a locking element (40) that is inserted in said bore (38) for blocking the interface nut (22) relative to the operating section (14). In particular, it is proposed that the locking element (40) is configured as a locking ball (42).