Talk:Linear actuator

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I came to this page looking for an explanation of "Stoke length". Could the article be expanded to technically explain/demonstrate what is meant by "actuator stroke length"? THANKS! ZacWolf (talk) 16:12, 15 March 2012 (UTC)

Stroke length generally refers to the maximum linear motion caused by any reciprocating mechanism. So, for example, the stroke length of a traveling-nut screw jack describes how far the nut can move from its minimum to maximum position. See the stroke article for more information. —Catsquisher (talk) 23:27, 15 March 2012 (UTC)

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On April 11, 2008, user 117.201.49.3 removed a significant portion of this document (accidently?) including the images showing how an electromechanical linear actuator works. I merged the deleted content back into the current version and made the following changes.

1. Removed comparisons of linear actuators to "other methods of providing linear motion". The definition of a linear actuator is essentially ANY device that produces linear motion. Therefore, there are no "other methods" (or if there are, they should be stated).
2. Created a table of advantages and disadvantages with reference to each actuator type since it was not clear before which types of actuators were being referred to.
3. Generally cleaned up the organizational structure of the page

- Rsteves00 (talk) 00:13, 10 May 2008 (UTC)

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I added a photo I took of a linear actuator manufactured by Zaber Technologies Inc. I'm a wiki newbie and not completely up to speed on copyright issues, but I assume because I took the picture myself that I am the copyright holder? - Rsteves00 02:09, 19 October 2007 (UTC)

Looks fine. You've specified the correct copyright status when you uploaded the image. If you're looking for extra challenge points you could take several pictures of it in several positions and create an animated GIF that shows it in action. :) Thanks for the image. --Hooperbloob 02:49, 19 October 2007 (UTC)

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I updated the entire entry to fix grammar and confusing sentences, and slightly changed the nesting structure of the titles to make them easier to follow. My major change was updating the electro-mechanical actuator section, where I added an animated image of an actuator in operation. The previous example was valid, but very hard to conceptualize to laymen (it also includes some design specific terms that are not industry standard as far as I know), and I thought a simpler example could be useful. I kept the old example and all information that was already on the page, but some of it is reorganized slightly. I also revised the advantages and disadvantages, as they were confusing with some applying only to a specific type of actuator, but not actually mentioning which one they were referring to. Bcraig15 03:03, 17 July 2007 (UTC)

Help needed

I've revised the intro, added the most common mechanical linear actuator types and their principles of operation (along with a reference), added pneumatic cylinders, and added many links to other pertinent articles. I left most everything else the same because my interests lie elsewhere at the moment, but this article still needs a lot of help, including more references and clearer descriptions. --Catsquisher (talk) 02:05, 10 August 2010 (UTC)

requested photo

There are 2 slightly different kinds of linear actuator#Electro-mechanical actuators that use a lead screw. Do these 2 kinds of actuators each have a more specific name to distinguish them from each other?

• The motor stays attached to one end of the lead screw (perhaps indirectly through a gear box), the motor spins the lead screw, and the lead nut travels up and down the lead screw. There's a pretty good diagram of this in the article.
• The lead screw passes entirely through the motor. The lead screw never spins; the only spinning parts are inside the motor, and may not even be visible from the outside. The motor "crawls" up and down the lead screw. I wish this article had a diagram of this in the article.

I wish this article also had photos of the internal parts and internal workings both these kinds of actuators. --68.0.124.33 (talk) 22:57, 4 December 2010 (UTC)

The two basic types of screw-driven linear actuator you asked about are described as either traveling screw or traveling nut. If rotation of the screw is restrained it's of the traveling screw type--the nut rotates and the screw moves. If rotation of the nut is restrained it's of the traveling nut type--the screw rotates and the nut moves. Catsquisher (talk) 23:56, 4 December 2010 (UTC)

Thank you, Catsquisher. I added those terms to the article; now it needs some images ... --68.0.124.33 (talk) 20:09, 22 December 2010 (UTC)

linear actuator + absolute encoder + force feedback?

Is there such a thing as a compact electric linear actuator that has an "absolute position reporting" encoder, with the ability to measure forces pushing or pulling on the end of the actuator?

I have been looking all over the Internet and so far I cannot find anything like this. It seems odd because I would think a linear actuator like this would be in high demand for dynamic motion robotics systems.

DMahalko (talk) 18:22, 28 June 2011 (UTC)

No mention of solenoids??

I notice that the article contains not a single mention of solenoids. Are solenoids not considered to fit the definition of linear actuators? (If not, I'd be curious to know why.)

Convit (talk) 14:15, 6 August 2013 (UTC)

Thanks

Kudos to the writers of this page. Excellent imaging & graphics work. — Preceding unsigned comment added by 130.154.0.250 (talk) 17:40, 12 August 2013 (UTC)

Merging hydraulic/pneumatic cylinder, linear actuator

I am proposing a merger between linear actuator, hydraulic cylinder, and pneumatic cylinder, though what form exactly, that needs to be worked out. Please discuss this on the Linear actuator talk page.

It looks like these engineering articles are being developed along the specific lines of knowledge that people have developed within their particular field of study, rather than as an encompassing view that includes similar aspects across all fields.

It's very unclear to me why we need two huge separate articles for hydraulic cylinders and pneumatic cylinders, when the biggest difference between them can be described as "this one's filled with liquid" and "this one's filled with gas".

Otherwise, they're basically identical in many other respects: single acting, double acting, reverse acting, single acting spring return, welded, tie rod. And then there's the topics that apply to all linear actuators including electric/screw actuators, like side loading.

It seems both the hydraulic and pneumatic articles should be slimmed down considerably and the duplicate content moved somewhere else, possibly here, or maybe to a new more generic term that just covers cylinders such as an article or subsection here called "Cylinder linear actuators".

Please discuss this on the Linear actuator talk page. -- DMahalko (talk) 18:40, 2 March 2015 (UTC)

The linear actuator includes a large number of devices besides hydraulic and pneumatic so merging linear actuator with either of these does not seem complete. RJFJR (talk) 18:47, 2 March 2015 (UTC)

The linear actuator article seems to be mostly about the electric screw type, but it's wrong to just have the article only about them. They are a subtype of linear actuators alongside pneumatic and hydraulic linear actuators. I'm not aware of a more specific name for them, but Electric linear actuator is probably a more appropriate separate article just for them.

Also if we're going to be really accurate and focus on the drive mechanism directly then electric actuators are typically a Screw linear actuator .. which by the way could be operated by both a hydraulic gear pump and a pneumatic air motor.

This also nicely separates out solenoids as a Magnetic linear actuator. -- DMahalko (talk) 18:56, 2 March 2015 (UTC)

The linear actuator article does include pneumatic and hydraulic types. It also includes some rather unusually types too. RJFJR (talk) 19:25, 2 March 2015 (UTC)

• oppose Very obvious fundamental principles behind them, why would you even think this is a good idea? Andy Dingley (talk) 23:31, 2 March 2015 (UTC)

There's no need to be dismissive and condescending. 95% of the hydraulic cylinder article can be directly pasted into the pneumatic cylinder article and still be completely accurate, and vice-versa.

Therefore the articles should only cover the specific "obvious and fundamental" details important to that particular type and its use, while the generalities between them can go somewhere else combined. Otherwise it's a mess trying to keep the fully-duplicated sections of both articles synchronized. -- DMahalko (talk) 02:06, 3 March 2015 (UTC)

Merger isn't about article content, it's about the scope of article topics. A merger states that not only is there overlap in the current content, but that the topics are such synonyms that we shouldn't even try to separate or distinguish them in the future. Andy Dingley (talk) 00:26, 4 March 2015 (UTC)

Same:

Components of cylinder design

Single rod, double rod, telescoping

Rod construction, materials, coatings

Side loading (pneumatics can leak too, though not usually as big an issue)

Position sensing methods

Failsafe, overpressure, bleed-off methods

Tie rod, welded, flange, threaded body

Instroke/Outstroke force difference due to rod on one side of piston

Different:

Hydraulic: incompressible fluid, nearly instant valve to cylinder reaction time, holds intermediate positions better

Pneumatic: compressible gas, delay before initial motion depending on seal friction, non-rigid support at comparatively low gas pressures, typically utilizing full-stroke motion due to inability to hold intermediate positions accurately

Though what is specifically different is really more a general discussion appropriate for the Hydraulics and Pneumatics articles.

-- DMahalko (talk) 02:24, 3 March 2015 (UTC)