Twist Resistant Elevator Suspension Member Pre-Tensioning

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Solution Overview

Problem

Elevator suspension members with tension members encased in compressible polymer jackets experience twisting and tracking issues due to unequal permanent stretch during operation, leading to misalignment and reduced performance.

Innovation Solution

Pre-tensioning the elevator suspension member by applying a load of ¼ to 1/9 of its load rating to adjust low load elongation of tension members before operation, using methods such as passing over sheaves or adding weight during installation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pre-tensioning is applied to adjust low load elongation, then twisting and tracking issues are reduced, but additional installation steps and time are required

Engineering Contradiction:

Improvetracking stabilityVSAvoidinstallation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies pre-tensioning to the suspension member during manufacturing or installation before the elevator begins operation. This preliminary action equalizes the elongation of tension members and eliminates future twisting and tracking issues, resolving the technical contradiction by performing the corrective action in advance rather than during operation.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If pre-tensioning load is increased to equalize elongation, then twisting is reduced, but higher forces are required during installation

Engineering Contradiction:

Improvebelt alignmentVSAvoidpre-tensioning force

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The patent specifies precise parameter ranges for pre-tensioning force (between 1/9 and 1/4 of the load rating) and low load elongation (between 1.5% and 3.0%). By optimizing these parameters, the patent achieves effective twisting prevention while minimizing the required pre-tensioning force, resolving the contradiction between alignment quality and installation force requirements.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If pre-tensioning is applied during manufacturing, then tracking performance is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improveoperational performanceVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent incorporates pre-tensioning as a preliminary manufacturing step that equalizes tension member elongation before the suspension member is installed in the elevator. This advance action ensures optimal tracking performance during operation while the added process complexity is confined to the manufacturing stage rather than affecting operational complexity.

Inventive Principle:

Principle #10Preliminary action

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

Reduces twisting and tracking issues by equalizing elongation, improving belt performance and reducing downtime through balanced tension and extended lifespan.

Implementation Method 1

pre-tensioning an elevator suspension member to adjust low load elongation of tension members within the elevator suspension member

Methodology Applied

Scientific EffectTension: Tension

Implementation Method 2

adjust low load elongation of tension members

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20250346454A1Twist resistant elevator suspension member

Publication Date: 2025.11.13 OTIS ELEVATOR CO

AI summary

A method and assembly includes pre-tensioning an elevator suspension member to adjust low load elongation of tension members within the elevator suspension member prior to placing the elevator suspension member in operation for an elevator.