Rod that slides up easily but slowly on way down

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Discussion Overview

The discussion revolves around the design of a mechanism that allows a rod to move upwards easily while slowing down or stopping during its descent, without the application of external energy. Participants explore various mechanical solutions and concepts related to this problem.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses a need for a mechanism that allows a rod to ascend easily but descend slowly or stop, inviting further questions for clarification.
  • Another participant suggests the use of a ratchet mechanism as a potential solution.
  • A hydraulic shock absorber mechanism with one-way valves for different damping rates is proposed as an alternative approach for controlling the rod's movement.
  • A hand bicycle pump is mentioned as a possible concept related to the mechanism being discussed.
  • A participant indicates a preference for the ratchet design, noting its efficiency in energy use and the ability to time the descent accurately, while acknowledging the hydraulic pump idea as a viable option that may consume some energy.

Areas of Agreement / Disagreement

Participants present multiple competing views on the mechanisms that could achieve the desired movement of the rod, with no consensus reached on a single solution.

Contextual Notes

Some ideas presented may depend on specific design parameters or assumptions about the rod's environment and the forces acting on it, which are not fully explored in the discussion.

Who May Find This Useful

Individuals interested in mechanical design, engineering solutions for motion control, or those exploring innovative mechanisms for movement may find this discussion relevant.

manp
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I'm sort of stuck on a fiddly point at the moment. I'm trying to make a rod go upwards with ease but slow down on the way down (or even stop for a few seconds) when it has been completely let go by the pulling action (without any external energy). Anyone have any clues of how I can achieve this? Please ask me questions for additional details as I may have missed out vital points to include in my post.
 
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Something like a ratchet?
 
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manp said:
I'm sort of stuck on a fiddly point at the moment. I'm trying to make a rod go upwards with ease but slow down on the way down (or even stop for a few seconds) when it has been completely let go by the pulling action (without any external energy). Anyone have any clues of how I can achieve this? Please ask me questions for additional details as I may have missed out vital points to include in my post.

mfb said:
Something like a ratchet?

Or a hydraulic shock absorber mechanism with 1-way valves for different damping rates for the up and down directions...?
 
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berkeman said:
Or a hydraulic shock absorber mechanism with 1-way valves for different damping rates for the up and down directions...?

My first thought exactly
 
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A hand bicycle pump come to mind.
 
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Thanks all, I've got a superb idea now, I am going down the ratchet route although a hydraulic type pump was also a good idea but takes up a small amount of pull energy due to the tight conceals I would've had to put around it. Whereas with the ratchet design I'm thinking of there would be almost no extra energy needed and more crucially I can time it to execute an exact timed drop. Cheers all, this forum is the best :)
 

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