Bayonet Thrust Nut Assembly for Corrosion-Free Hydrant Retention
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Solution Overview
Problem
Traditional fire hydrants with threaded thrust nuts require frequent manual adjustments to prevent water hammer events, are prone to corrosion from anti-ice road salt, and risk cross-threading damage, necessitating skilled and time-consuming maintenance.
Innovation Solution
A bayonet thrust nut assembly with locking features that threadlessly secure the operating nut within the bonnet, using a thrust nut with bayonet locking features and a lock plate to prevent vertical movement and corrosion, eliminating the need for traditional threading and reducing maintenance complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threaded thrust nut is used to control vertical movement of the main valve, then water hammer events can be prevented, but frequent manual adjustment is required and maintenance becomes time-consuming
Solution Approach 1:
The thrust nut is designed with self-adjusting features including a spring mechanism that automatically compensates for wear and corrosion, eliminating the need for frequent manual adjustments. The spring maintains constant pressure on the operating nut, ensuring continuous prevention of water hammer events without human intervention.
Solution Approach 2:
The invention changes the physical state of the thrust nut from a rigid threaded connection to a flexible spring-loaded mechanism. This parameter change allows the thrust nut to automatically adapt to varying conditions (corrosion, wear) by adjusting its position, thereby maintaining reliable water hammer prevention while reducing maintenance frequency.
2Force
If a threaded thrust nut made of copper alloy is used, then the thrust nut can bear vertical loads, but road salt causes corrosion of the iron bonnet threads making removal difficult
Solution Approach 1:
The thrust nut assembly uses a composite design combining a copper alloy thrust nut for load bearing with a zinc-plated steel bonnet for corrosion resistance. The galvanic coupling between these dissimilar metals, combined with the zinc plating barrier, protects the iron bonnet threads from road salt corrosion while maintaining the vertical load bearing capacity of the copper alloy nut.
Solution Approach 2:
The invention introduces a zinc plating layer as an intermediary between the iron bonnet threads and the corrosive road salt environment. This zinc coating acts as a sacrificial anode and physical barrier, preventing direct contact between the salt and iron threads, thereby eliminating the corrosion problem that makes removal difficult.
3Reliability
If a threaded thrust nut is used to secure the operating nut, then the operating nut can be retained, but cross-threading can permanently damage the threads requiring component replacement
Solution Approach 1:
The invention segments the securement function into two independent parts: the bayonet-style locking mechanism for retention and the threaded connection for positioning. This segmentation allows the operating nut to be securely retained through the bayonet lock without relying on threaded engagement, thereby eliminating cross-threading damage while maintaining securement reliability.
Solution Approach 2:
The invention replaces the traditional threaded mechanical connection with a bayonet-style quarter-turn locking mechanism. This substitution eliminates the threading interface that is susceptible to cross-threading damage, while the bayonet lock provides equally reliable securement of the operating nut through a different mechanical principle based on radial engagement rather than axial threading.
4Reliability
If traditional threading is used to install the thrust nut, then the thrust nut can be secured to the bonnet, but precise alignment and threading skill are required increasing installation time
Solution Approach 1:
The invention inverts the traditional installation sequence by first securing the thrust nut to the operating nut via a simple bayonet lock, then attaching the assembly to the bonnet. This reversal eliminates the need for precise threading alignment during the critical securement step, as the bayonet lock tolerates misalignment and can be installed by simple insertion and rotation rather than skilled threading.
Data Source
AI summary
A threadless bayonet thrust nut assembly for a hydrant, a bayonet thrust nut, and a hydrant having the same, the assembly including the bayonet thrust nut with locking features extending radially therefrom, a hydrant bonnet having retainer lugs disposed around a top opening and corresponding to the locking features, and a lock plate having downwardly extending bayonet extensions, where the locking features are configured to pass through spaces delimited by the retainer lugs when the thrust nut is maneuvered through the opening into the bonnet, where the thrust nut is rotatable between an open position in which the locking features are aligned with the spaces and a closed position in which the locking features are aligned with the retainer lugs, where the bayonet extends of the lock plate are insertable into the spaces when the thrust nut is in the closed position, and where the thrust nut in the closed position is driven against an underlying operating nut disposed with in the bonnet so as to threadlessly secure the operating nut within the hydrant.