Swivel Lug Assembly for Spreader Bar Lifting

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Solution Overview

Problem

Existing spreader bar systems for lifting tubulars often exert bending moments on the spreader bar, leading to increased stress and reduced structural capacity, and require precise alignment and material alteration, limiting their versatility and efficiency in accommodating various load dimensions and weights.

Innovation Solution

The design of swivel lug assemblies that can be adjustably placed along the spreader bar to eliminate bending moments by applying loads along the centerline, self-align with the fleet/sling angle, and attach/detach quickly without material alteration, ensuring a pure compressive state and increased structural capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If end cap systems are used to attach spreader bars to lifting mechanisms, then the spreader bar can be connected to multiple lifting points, but the system requires precise alignment and material alteration (spot welds or attachment holes) which weakens the spreader bar's structural capacity

Engineering Contradiction:

Improveattachment capabilityVSAvoidspreader bar structural capacity

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The end cap is divided into two separate components: a first cap portion that attaches to the spreader bar and a second cap portion that connects to the lifting mechanism. This segmentation eliminates the need for material alteration of the spreader bar, as the caps can be attached using external fastening methods that preserve the bar's structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The end cap system acts as an intermediary component between the spreader bar and the lifting mechanism. It provides a standardized interface that accommodates various lifting configurations without requiring modification of the spreader bar itself, thereby maintaining its strength while enhancing adaptability.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If end cap systems are used with fixed attachment points, then the attachment process is simplified, but the system can only accommodate specific load dimensions and weights, limiting versatility

Engineering Contradiction:

Improveattachment process simplicityVSAvoidaccommodation of various load dimensions

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The end cap system incorporates adjustable components that allow the attachment points to be repositioned along the spreader bar. This dynamic adjustment capability enables the same end cap system to accommodate various load dimensions and weights while maintaining a simple attachment process through standardized fastening mechanisms.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If tube lugs are used to attach lifting slings to the spreader bar, then multiple lifting points are provided, but bending moments are exerted on the spreader bar increasing stress and reducing structural capacity

Engineering Contradiction:

Improvemultiple lifting pointsVSAvoidbending moment stress

Core Design Contradiction:

Adaptability or versatilityVSStress or pressure

Solution Approach 1:

Instead of attaching lifting slings directly to the spreader bar at offset positions (which creates bending moments), the invention inverts the approach by using end caps that extend the attachment points to the ends of the spreader bar. This reversal of the attachment geometry aligns the lifting forces with the longitudinal axis of the bar, eliminating bending moments while maintaining multiple lifting points capability.

Inventive Principle:

Principle #13The other way round (Inversion)

4Reliability

If precise alignment is required for end cap attachment, then the attachment is secure, but the rigging process becomes time-consuming and prone to error

Engineering Contradiction:

Improveattachment securityVSAvoidrigging time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The end caps are pre-configured with alignment features and standardized attachment geometries that guide the rigging process. This preliminary preparation of the attachment components eliminates the need for complex field alignment procedures, reducing rigging time while maintaining secure attachments through inherent mechanical guidance features.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11708246B2Swivel lug assembly and system for lifting a load via a spreader bar

Publication Date: 2023.07.25 MYERS CLAYTON P

AI summary

A system for lifting a load via a spreader bar includes a spreader bar and a swivel lug assembly. The swivel lug assembly includes an upper swivel, a lower swivel, and a load pin extending between a pair of load pin holes in the upper swivel and the lower swivel. The upper swivel is pivotable relative to the lower swivel about the load pin. The spreader bar includes two opposing sides each having a height, and spreader bar pin holes in each of the sides. The spreader bar pin holes are located at a midpoint of the height of each of the sides. The load pin is detachably attached to the first swivel lug assembly through the pair of load pin holes in the upper swivel and the lower swivel in order to releasably attach the swivel lug assembly to the spreader bar via two opposing spreader bar pin holes.