Extendable Tripod Leg With Cable-Actuated Multi-Stage Locking

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Solution Overview

Problem

Existing tripod legs are cumbersome and heavy due to mechanical linkages, making them difficult to use and expensive to manufacture, while prior art mechanisms, such as those using torsion rods and push rods, detract from ease of use and increase weight.

Innovation Solution

An extendable tripod leg design featuring two or more leg-stages with a clamp assembly and actuation means, utilizing a cable connected to a leg brake, allowing for relative movement and simultaneous operation of multiple stages with a single hand, incorporating a Bowden cable for light yet strong components and minimizing adjustment needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If mechanical linkages such as torsion rods and push rods are used to connect the operating lever to the locking mechanisms, then the locking mechanism can be operated remotely, but the tripod becomes heavier and more cumbersome

Engineering Contradiction:
Improveremote operation of locking mechanismVSAvoidweight of tripod leg
Core Design Contradiction:
Ease of operationVSWeight of moving object

Solution Approach 1:

The patent replaces traditional mechanical linkages (torsion rods, push rods) with a cable-based system. The cable connects the operating lever to the locking mechanism, allowing remote operation while significantly reducing weight and complexity. The cable can accommodate relative movement between leg sections without requiring complex mechanical joints.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If heavy mechanical linkages are used to link the operating lever to remote locking mechanisms, then the locking can be achieved, but the tripod becomes more expensive to manufacture and difficult to carry

Engineering Contradiction:
Improvelocking mechanism reliabilityVSAvoidmanufacturing complexity and cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The cable-based system replaces complex mechanical linkages, simplifying manufacturing while maintaining reliable locking. The cable system requires fewer precision-machined parts and can be more easily assembled and adjusted during manufacturing.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The cable acts as an intermediary element that transmits the operating force from the lever to the locking mechanism while accommodating relative movements. This intermediary approach simplifies the direct mechanical connection requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If a single operating lever is used to operate all locking mechanisms, then ease of use is improved, but complex remote operating mechanisms with heavy linkages are required

Engineering Contradiction:
Improvesingle-hand operation of all locksVSAvoidcomplexity of remote operating mechanism
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The cable system enables a single operating lever to control multiple locking mechanisms without requiring complex mechanical transmission systems. Each locking mechanism is independently connected via cable, allowing simple lever operation while reducing overall system complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP3221631B1An extendible tripod leg
Publication Date: 2018.04.11 VITEC GRP PLC
  • EP3221631B1 patent drawingFigure 1
  • EP3221631B1 patent drawingFigure 2
  • EP3221631B1 patent drawingFigure 3

AI summary

An extendable leg (10) for a tripod., the leg (10) comprises two or more leg-stages (11b, 11c), each leg-stage (11b, 11c) moveable axially relative to one or more of the or each other legstages to lengthen or shorten the leg. The leg (10) includes a damp assembly to releasably prevent the relative movement when the leg is at the desired length. The damp assembly includes a leg brake (22a) moveable between a first leg-stage locking position and a second leg-stage release position. In order to control movement of the leg brake (22a) between the first and second positions, an actuation means (16) is provided. A cable (17) is operably connected at a first end to the actuation means (16) and at a second end to the leg brake (22a), such that operation of the actuation means (16) causes the cable (17) to move the leg brake (22a).