Telescoping Boom Wear Pad Assembly With Expandable Collet Locking
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Solution Overview
Problem
Existing wear buttons for telescoping booms fail to maintain secure engagement under heavy loads and repetitive shock, leading to jamming, cross-threading, and ejection issues due to loose adjusters and worn threads.
Innovation Solution
A wear pad assembly featuring a cylindrical body with a screw thread and internally tapered expandable collet, combined with a base having an externally tapered mandrel portion, which creates an interference fit to enhance load capacity and prevent unwanted movement, along with a fastening system using working bolts and spring washers for secure tensioning and easy adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional steel backing with male thread and locking cover is used, then the wear button can be adjusted, but the adjuster works loose after short service period causing jamming and cross-threading
Solution Approach 1:
The wear button is divided into separate functional components: a wear pad element and a base element with threaded engagement. This segmentation allows the threaded base to remain stationary while only the wear pad needs adjustment, eliminating thread wear issues while maintaining adjustability.
Solution Approach 2:
The threaded engagement feature is extracted from the adjustable component and placed in the stationary base. This removes the threaded part from the moving/adjustable portion, preventing thread wear and loosening while preserving the ability to adjust the wear pad position.
2Strength
If traditional adjuster and locking plate design is used, then the wear button can be secured, but the adjuster is ejected or cross-threaded under heavy shock loads
Solution Approach 1:
The wear pad is pre-loaded against the boom surface through the tensioning bolt before service begins. This preliminary action ensures that under subsequent shock loads, the wear pad remains firmly pressed against the surface, preventing ejection and cross-threading while maintaining strength.
Solution Approach 2:
The shock loads that would normally cause loosening and ejection are converted into beneficial compressive forces that press the wear pad more firmly against the boom surface. The tensioning bolt system transforms harmful dynamic loads into useful pre-compression that enhances reliability under heavy service conditions.
3Ease of operation
If traditional wear button design is used, then the boom sections can slide, but free play and slop develop due to thread wear
Solution Approach 1:
By separating the threaded engagement function from the sliding adjustment function, the invention eliminates thread wear that causes play and slop. The stationary threaded base maintains precise positioning while the wear pad slides smoothly against the boom surface without compromising manufacturing precision.
Solution Approach 2:
The tensioning bolt acts as an intermediary that maintains precise positioning and eliminates play between components. It transfers and distributes loads uniformly, preventing the development of free play and slop that would otherwise occur with traditional threaded adjusters under repeated sliding movements.
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 provides increased load carrying capability, resistance to corrosion and thread binding, and facilitates easy extraction and adjustment of the wear pad without damaging the boom, ensuring reliable operation under heavy loads.
Implementation Method 1
the externally threaded part is threadably engaged in the threaded bore and expanded therein by insertion of the externally and complementarily tapered mandrel portion in the expandable collet
Data Source
Figure 1
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AI summary
This disclosure relates to a wear button or pad for a telescoping boom of the type comprising at least an outer boom member comprising a threaded bore therethrough for the wear pad assembly, and an inner boom member that is slidable with respect to the outer boom member. In one form, the wear pad assembly comprises a wear pad and a base, a first of which comprises a generally cylindrical body comprising a curved external side surface comprising a screw thread via which this is threadably engageable in the threaded bore, and an internally tapered expandable collet, and the second of which comprises an externally and complementarily tapered mandrel portion, wherein in use, the externally threaded part is threadably engaged in the threaded bore and expanded therein by insertion of the externally and complementarily tapered mandrel portion in the expandable collet.