Shaft Brake Layout for Damage-Free Tool Stopping

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Solution Overview

Problem

Existing braking mechanisms for tools, such as saw blades, often result in damage to both the saw blade and the braking mechanism, necessitating frequent replacements and increased operational effort.

Innovation Solution

A tool device with brake elements arranged circumferentially around the shaft that move from a release state to a braking state, where they contact the shaft to exert a braking force, and are guided by the shaft's movement during the transition, minimizing damage and allowing for quick reversibility without component replacement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a pawl engages with the saw blade to stop it, then the saw blade can be braked, but both the saw blade and the pawl are damaged requiring replacement

Engineering Contradiction:
Improvebraking capabilityVSAvoidcomponent durability
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The braking system is segmented into multiple independent brake bodies (at least two) arranged circumferentially around the shaft, where each brake body can independently contact the shaft to provide braking force. This segmentation distributes the braking stress and prevents single-point failure that causes damage in traditional single-pawl systems.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of having the brake element actively engage the rotating blade (which causes impact damage), the system inverts the approach by having brake bodies contact the shaft in a manner that is guided and supported by the shaft's own movement. The shaft's rotation guides the brake bodies into the braking state, reversing the traditional active-engagement model and eliminating damaging impacts.

Inventive Principle:
Principle #13The other way round (Inversion)

2Productivity

If traditional braking mechanisms are used, then the tool can be stopped, but frequent replacements of blade and brake components are necessary

Engineering Contradiction:
Improveoperational continuityVSAvoidreplacement time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The brake bodies are designed to be non-consumable components that do not get damaged during braking operation. Unlike traditional pawls that wear out or break, these brake bodies can be reused indefinitely without replacement, allowing the system to discard the old damaging design and recover continuous operational capability.

Inventive Principle:
Principle #34Discarding and recovering

3Force

If brake elements are moved to contact the shaft for braking, then braking force is applied, but operational effort increases

Engineering Contradiction:
Improvebraking forceVSAvoidactuation effort
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The shaft's own rotational movement serves to guide the brake bodies into the braking state. The system uses the shaft's motion itself to facilitate the engagement of brake elements, making the braking process self-actuating and eliminating the need for additional actuation effort from the operator.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The brake bodies are designed to dynamically transition between release and braking states based on the shaft's movement. The system is not statically engaged but dynamically responds to shaft rotation, allowing automatic engagement and disengagement that reduces operational effort while maintaining effective braking force when needed.

Inventive Principle:
Principle #15Dynamics

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 tool device effectively brakes the tool without damaging it or the brake elements, enabling continued operation without needing replacements and reducing operational effort.

Implementation Method 1

the several brake elements are in contact with the shaft and thereby exert a braking force on the shaft

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3956116B1Tool device and method
Publication Date: 2026.03.18 FESTOOL GMBH
  • EP3956116B1 patent drawingFigure 1
  • EP3956116B1 patent drawingFigure 2
  • EP3956116B1 patent drawingFigure 3

AI summary

The invention relates to a tool device (10) having a drivable tool (1), comprising a shaft (2) coupled to the tool (1), also comprising one or more braking elements (3) that are arranged in a manner distributed in particular in the circumferential direction (4) about the shaft, wherein the tool device (10) is configured, as part of a braking operation, to move the one or more braking elements (3) from a released state into a braking state, wherein, in the braking state, the one or more braking elements (3) are in contact with the shaft and as a result exert a braking force on the shaft (2) such that the shaft (2) and as a result also the tool (1) are braked, and wherein, in the released state, the one or more braking elements (3) are not in contact with the shaft (2).