Composite Elevator Sheave Liner for Durable Easy Replacement

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Solution Overview

Problem

Existing elevator sheave liners, such as plastic ones, are not durable and require precise machining for installation, limiting material options and increasing replacement costs.

Innovation Solution

A sheave assembly with a rigid central portion made of metal and a resilient outer portion made of elastomer, such as thermoplastic polyurethane, which is over-molded or snap-fit onto the sheave, providing easy installation and durability without complex machining.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If plastic sheave liners are used, then cost is reduced and traction is improved, but durability is insufficient and wear resistance is poor

Engineering Contradiction:
ImprovedurabilityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The sheave liner combines a rigid metal central portion (providing durability and wear resistance) with a resilient outer portion made of polymer material (providing traction and shock absorption). This composite structure resolves the contradiction by integrating materials with complementary properties to achieve both durability and manufacturing feasibility.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

Different regions of the sheave liner have different material properties: the central portion uses rigid metal for structural integrity and wear resistance, while the outer portion uses resilient polymer for traction and cushioning. This local differentiation of material quality allows each region to perform its specific function optimally.

Inventive Principle:
Principle #3Local quality

2Reliability

If cast iron sheaves are used, then durability is improved, but replacement cost increases and maintenance complexity increases

Engineering Contradiction:
ImprovedurabilityVSAvoidreplacement cost
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

The sheave system is segmented into a permanent cast iron sheave and a replaceable sheave liner. The liner can be removed and replaced without replacing the entire sheave, reducing maintenance costs and complexity while maintaining durability through the rigid metal central portion of the liner.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of replacing expensive cast iron sheaves, the invention uses a more economical replaceable liner that can be worn and replaced. The rigid metal central portion provides sufficient durability while the overall replacement cost is lower than replacing entire cast iron sheaves.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Manufacturing precision

If precision machining is used for sheave liner fitting, then fit quality is improved, but manufacturing cost increases and manufacturing time increases

Engineering Contradiction:
Improvefit qualityVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The resilient outer portion acts as a flexible element that accommodates fit variations through elastic deformation. This flexibility allows the liner to achieve adequate fit quality without requiring precision machining, as the resilient material compensates for dimensional tolerances.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the physical parameters of the sheave liner by using resilient material with specific elastic properties. This allows the liner to adapt to the sheave surface through elastic deformation, achieving acceptable fit quality without precision machining and reducing manufacturing costs.

Inventive Principle:
Principle #35Parameter changes

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 solution offers economical and durable sheave liners that can be easily replaced, maintaining sheave integrity and allowing for a variety of materials, reducing maintenance costs and extending sheave life.

Implementation Method 1

a resilient outer portion made of a second material... The resilient layer has an exterior profile that cooperates with surfaces on the other of the rigid sheave liner and the sheave to secure the rigid sheave liner to the sheave

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

A rigid sheave liner is made of a first material... the first material comprises metal... The central portion defines a traction surface that is configured to receive an elevator tension member

Methodology Applied
Scientific EffectElastic modulus: Elasticity

Data Source

PatentEP3770100B1Elevator sheave liner
Publication Date: 2026.04.29 OTIS ELEVATOR CO
  • EP3770100B1 patent drawingFigure 1~4
  • EP3770100B1 patent drawingFigure 5

AI summary

An illustrative example embodiment of elevator sheave liner (40) includes a rigid central portion (42) made of a first material and a resilient outer portion (46) made of a second material. The central portion (42) defines a traction surface (44) that is configured to receive an elevator tension member. The outer portion (46) defines an engagement surface (48) that is configured to secure the sheave liner (40) to an elevator sheave (30).