Locking Dog Assembly With Cam Actuation for Safer 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 are difficult to use due to ergonomic challenges, posing safety hazards and operational difficulties.
Innovation Solution
A locking dog assembly with a mechanism for simultaneous operation of both locking dogs, featuring a cam assembly or other mechanisms like rack and pinion, lead screw, solenoid, or hydraulic actuation, which provides mechanical advantage and protects the springs from over-compression, enhancing ergonomics and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spring-loaded locking dogs are used to secure anchors, then the anchor is securely held in the engaged position, but the springs can be damaged by backlash events resulting in impaired locking function and safety hazards
Solution Approach 1:
The patent applies beforehand cushioning by providing a stop mechanism that limits the outward travel of locking dogs before the springs can be over-compressed during backlash events. The stop is positioned to engage the locking dog at a predetermined point, cushioning the spring from excessive compression forces that would occur during sudden reverse rotation or mechanical failures.
2Reliability
If significant spring force is used to hold locking dogs in engaged position, then secure locking is achieved, but significant force (e.g., about 20 pounds) is required to compress the spring when disengaging
Solution Approach 1:
The patent applies segmentation by dividing the locking dog into multiple components: a body portion that engages the anchor, a separate operating ring at the outer end, and an intermediate section with a cam surface. This segmentation allows the operating ring to rotate independently, providing mechanical advantage that reduces the force needed to overcome spring pressure during disengagement.
Solution Approach 2:
The patent uses an intermediary cam surface mechanism between the operating ring and the locking dog body. When the operating ring rotates, it acts on the cam surface which translates the rotational motion into controlled linear motion of the locking dog, providing mechanical advantage and reducing the direct force required to compress the spring.
3Adaptability or versatility
If locking dogs are positioned high above ground level (e.g., seven feet or more), then the drive tool can secure anchors at elevated positions, but it becomes difficult for the operator to produce enough force to disengage the locking dogs
Solution Approach 1:
The operating ring serves as an intermediary lever arm that the operator can grip and rotate. This intermediary mechanism allows the operator to apply force at a convenient location on the tool rather than directly pulling on the locking dog, making operation feasible even when the locking dogs are positioned seven feet or more above ground level.
4Adaptability or versatility
If locking dogs are operated independently, then each locking dog can be controlled separately, but disengaging the second locking dog can jar the tool and cause the first locking dog to reengage
Solution Approach 1:
The patent merges the operation of both locking dogs through a common operating ring that simultaneously controls both dogs. When the operating ring rotates, it acts on both locking dogs at the same time, ensuring they disengage together without one dog jarring the tool and causing the other to reengage. This combining of operations maintains the stability needed during disengagement.
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 easier and safer operation of locking dogs, protecting the springs from damage and reducing the risk of safety hazards, while allowing for efficient disengagement even under binding conditions.
Implementation Method 1
A locking dog assembly is provided with a mechanism for simultaneous operation of both locking dogs
Implementation Method 2
Spring-loaded locking dogs or pins in the locking dog assembly catch under the head of the anchor to releasably secure the anchor in the wrench
Data Source
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AI summary
A locking dog assembly (100) including a body (110) including inner cavity (112) with a lower opening, a first locking dog (120a) at least partially extending through a first side of the body and displaceable into and out of the inner cavity, a second locking dog (120b) 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 (132) for simultaneous displacement of the first and second locking dogs with mechanical advantage.