Locking Dog Assembly With Mechanical Advantage for Safe Disengagement

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Solution Overview

Problem

Existing locking dog assemblies for drive tools used in installing helical anchors and piles are prone to damage from backlash events, require significant force for operation, and pose safety hazards due to impaired locking functions and difficult access positions.

Innovation Solution

A locking dog assembly with a mechanism for simultaneous operation of both locking dogs, featuring a cam assembly or other mechanisms like lead screw, rack and pinion, or hydraulic actuation, which provides mechanical advantage and protects springs from over-compression, allowing easier and safer operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If spring-loaded locking dogs are used to secure the drive wrench and anchor, then the locking function is reliable, but the springs can be damaged by backlash events releasing large amounts of stored energy instantaneously

Engineering Contradiction:

Improvelocking function reliabilityVSAvoidspring durability

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

A hydraulic damper is integrated into the locking dog assembly to absorb and dissipate the sudden kinetic energy from backlash events before it can damage the springs. The damper acts as a pre-positioned energy absorption mechanism that protects the spring-loaded locking dogs from excessive forces during abnormal operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Reliability

If significant spring force is used to hold locking dogs in engaged position, then secure locking is achieved, but significant force (about 20 pounds) is required to compress the spring when disengaging

Engineering Contradiction:

Improvelocking securityVSAvoiddisengagement effort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

A hydraulic actuator replaces the purely spring-loaded mechanical disengagement system. The hydraulic actuator provides controlled force to overcome the spring force during disengagement, reducing the manual effort required from the operator while maintaining secure locking during operation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

A hydraulic system is used to assist in compressing the spring during locking dog disengagement. The hydraulic actuator delivers controlled mechanical force to overcome the spring resistance, making operation easier while maintaining reliable locking engagement.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Reliability

If locking dogs are positioned seven feet or more above ground level, then secure retention of drive wrench is achieved, but it becomes difficult for the operator to produce enough force to disengage the locking dog

Engineering Contradiction:

Improvedrive wrench retentionVSAvoidoperator accessibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The hydraulic actuator system allows the operator to disengage locking dogs at elevated positions with minimal effort. The hydraulic assistance compensates for the mechanical disadvantage of reaching overhead, enabling easy operation even when locking dogs are positioned seven feet or more above ground level.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Power

If significant load is present between locking dogs and drive wrench, then secure transmission of driving force is achieved, but binding due to this load makes it very difficult to pull out the dogs

Engineering Contradiction:

Improvedriving force transmissionVSAvoidlocking dog extraction

Core Design Contradiction:

PowerVSEase of operation

Solution Approach 1:

The hydraulic actuator provides the necessary force to overcome binding caused by significant loads between the locking dogs and drive wrench. During disengagement, the hydraulic system delivers controlled force to extract the locking dogs even when substantial driving forces are present, maintaining both power transmission and operational ease.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 enhances ergonomics and safety by reducing the force required for operation, protecting springs from damage, and ensuring secure engagement/disengagement of locking dogs, even under binding conditions, thereby improving the overall efficiency and safety of the locking dog assembly.

Implementation Method 1

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Implementation Method 2

Spring-loaded locking dogs or pins in the locking dog assembly catch in holes in the drive wrench to releasably secure the drive wrench

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 3

The locking dog springs can be damaged by a backlash event during which a large amount of stored energy is released into kinetic energy instantaneously

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20230119835A1Locking dog assembly

Publication Date: 2023.04.20 HUBBELL INC

AI summary

A locking dog assembly including a body including inner cavity with a lower opening, a first locking dog at least partially extending through a first side of the body and displaceable into and out of the inner cavity, a second locking dog at least partially extending through a second side of the body, opposite the first side, and displaceable into and out of the inner cavity, and a mechanism for simultaneous displacement of the first and second locking dogs with mechanical advantage.