Talk:Car suspension

Put the "rear suspension" page in here...

"are more compliant. "

I don't agree with this change. David R. Ingham 07:06, 27 February 2006 (UTC)

Well, I wouldn't have changed it in the first place if you'd spelled rigid correctly! But to be honest there's no point in messing about with weasel words like 'perhaps more ridged' (quoting from memory) - the quarter elliptics will be more compliant than anything but the most grotesque of suspension arms. Anyway, by all means, have another go. Greglocock 23:07, 27 February 2006 (UTC)

What about...

What about the unique Ford twin I-beam independent front suspension? This system doesn't seem to be mentioned anywhere.

careful reading of names

Please note that the edit at 07:27, 27 February 2006 by David R. Ingharn was not by myself but someone who chose a name that resembled mine. David R. Ingham 06:58, 2 March 2006 (UTC)

Confusion regarding semi-active suspensions

This article mentions Hydragas and Kinetic systems as examples of semi-active suspensions; yet neither of these systems is inherently semi-active. In their base form, both systems (Kinetic actually have a number of systems) are passive interconnected schemes, whose advantages lie not in their ability to vary springing and damping parameters, but rather in their capacity to provide different springing and damping depending on the suspension mode in operation. Wade Smith 07:53, 9 March 2006 (UTC)

I think the confusion really comes about because semi-active may once have meant something but has been diluted into meaninglessness by the marketing boys. Hydragas in particular is just another passive suspension. Do you know of a formal definition for semi-active, or for that matter, active? It used to be whether external power was required, yet that seems a useless definition.Greglocock 09:29, 9 March 2006 (UTC)

I would take "active" to mean that the suspension uses external power to move the car. However, the active component article includes things that depend on the direction of the current, which would suggest including shock absorbers with valves as active. David R. Ingham 17:06, 9 March 2006 (UTC)

There are a number of definitions available, some better than others. I think the definitions given by Sharp & Crolla will suffice here, with some minor clarifications based on Gillespie’s work.

Passive Suspensions: consist of spring and damping properties which are time-invariant, or, at least, quasi-time-invariant. Thus most self-levelling systems could be categorised under this heading, since their capacity to fulfil their dynamic requirements is not affected by any adaptive capacity.

Active Suspensions: describe the replacement of springs and dampers with actuators that act as force producers according to some control law. The control bandwidth is usually sufficient to handle the natural frequencies of both the sprung (1-3 Hz) and unsprung masses (10-15 Hz).

Semi-Active Suspensions: contain spring and damping elements, the properties of which may be changed by external control. Most commonly, only the damper has adjustable parameters, but Gillespie makes the point that the springing may also be adjustable. The parameters may be varied either continuously or between a number of discrete settings. Perhaps a clear distinction between these and active suspensions is that semi-active systems lack the capacity to supply work. That is, the parameters that control the system’s reaction to an input (specifically, relative displacement or velocity) can be adjusted, but a more general ability to produce an arbitrary force is not apparent.

Slow-Active Suspensions: behave like active or semi-active suspensions, but only over a limited bandwidth. Sharp and Gillespie give different definitions here: Sharp sees slow-active suspensions as a sub-group of fully active systems, whereas Gillespie claims they’re included in the semi-active family (with the distinction of having discrete parameter settings, in which a switch in one direction is almost instantaneous, but the reverse switch is much slower). I think a definition which loosely encompasses both these views is possible. So, we might say that slow-active systems (or, more precisely, limited bandwidth suspensions) are simply active or semi-active systems, in which the capacity to fulfil dynamic requirements is limited to a certain bandwidth. But even fully active systems have limited bandwidths, so a further distinction is necessary. I think the most convenient one would be to say that these systems have the capacity to handle the sprung mass motions (1-3 Hz), but not the unsprung mass motions (10–15 Hz).

Interconnected Suspensions: are defined, by Smith & Walker, as suspension systems in which a displacement at one wheel station can produce forces at other wheel stations. Well-known examples include anti-roll bars, the Hydragas system, Kinetic systems etc. The advantage of these schemes is that one can achieve more control over the stiffness and damping of each suspension mode, instead of being entirely reliant upon single-wheel parameters to implicitly define modal characteristics. I can’t see why these systems couldn’t fit into any of the aforementioned categories, but a fully active interconnected scheme is probably not a meaningful concept, seeing as an active controller inherently has the capacity to adjust the actuator force in accordance with modal operation anyway.

So, in summary: active, semi-active and slow-active systems generally require external power which influences their dynamic operation; whereas passive systems generally do not require external power, or, if they do, it does not influence their dynamic operation. Active systems can supply work and handle sprung and unsprung mass motions; semi-active systems can’t supply work, but can cover sprung and unsprung mass frequencies; and slow-active systems can belong to either the active or semi-active group, but have limited bandwidths. Interconnected schemes can belong to any of those categories, but are more meaningfully conceptualised in either a passive or semi-active context.

References:

Gillespie, T. D. 1992, Fundamentals of Vehicle Dynamics, SAE International, Warrendale, PA.

Sharp, R. S. and Crolla, D. A. 1987, ‘Road Vehicle Suspension System Design – a review’, Vehicle System Dynamics, vol. 16, pp. 167-192.

Smith, M. C. and Walker, G. W. 2005, ‘Interconnected Vehicle Suspension’, Journal of Automobile Engineering, vol. 219, no. 3, pp. 295-307.

These definitions might not be entirely robust, but they’re a start. Hope that helps. Wade Smith 02:52, 10 March 2006 (UTC)

Definitions?

They suck. How exactly are the term being defined here?

It looks as though the signature above should be "03:41, 26 April 2006 70.26.11.45".

Which term or terms would you like someone to define better? (I won't ask for a clear definition of "suck", which has always seemed poorly defined to me.) David R. Ingham 04:20, 26 April 2006 (UTC)

Ride comfort data

Hai friends.,

I am doing project work on "Damping force variation reduction for front fork of two wheelers using Design of experiment". can you give me the Anthropometric data for riding comfort, for two wheeler in indian road condition.

Help!

Road vehicles are not the only wheeled vehicles requiring suspension systems. Some of us are interested in railway suspension. Does anybody know anything about it? Gordon Vigurs 09:06, 3 July 2006 (UTC)

Questions

Wiki is not a place to ask for advice. For suspension related questions, I recommend the newsgroup sci.engr.mech, or, IF you are a professional engineer, not a student, www.eng-tips.com in the appropriate forum.

Greglocock 13:42, 3 July 2006 (UTC)

Thank you, but I have access to appropriate sources - my point is that suspension is not just an automotive issue. The article should have gone from general (i.e. seismic oscillations) to particular (the details of specific vehicle suspension system designs), rather than jumped into the specifics from the outset. Please excuse my naive assumption that an encyclopedia should be a source of knowledge. Gordon Vigurs 17:42, 5 July 2006 (UTC)

Oops sorry, I was referring to the Indian guy asking for help, not you. You are right, the article does need a section on other forms of suspension.

Greglocock 09:04, 9 July 2006 (UTC)

Armoured fighting vehicle vs tracked vehicle

I gather from the article that the suspensions of armoured fighting vehicles face design challenges in the form of land mines and other explosive devices. Beyond this, are there appreciable differences between the suspension of a late model tank and, say, a civilian bulldozer, which faces similar terrain and is also a heavy, tracked vehicle? If not, would the article be improved by making armoured fighting vehicles a subsection of a section on tracked vehicles? Also, I remember (perhaps falsely) hearing about wheeled (non-tracked) armoured fighting vehicles - how do they connect with this section? Thanks --Badger151 15:50, 18 September 2006 (UTC)

"Kneeling" busses, &c.

Many of the public busses I now see are equiped to lower their front ends, reducing the height of the step into the bus from the pavement (and making it easier for people with movement limitations to enter the bus). Around here (NYC area) I've seen it called "kneeling", though it may have other names in other places. I'm also familiar with some ambulances that lower their back ends to ease loading and unloading of the stretcher. Is this a function of these vehicles' suspensions? If so, does it deserve treatment in this article? Thanks --Badger151 16:05, 18 September 2006 (UTC)

Picture

Isn't kind of weird that the picture for this article that deals with suspension for the car comes from a vehicle which was designed 98 years ago? Can we get a picture of a more modern car's suspension, as that picture only shows control arms and a spring on a very very antiquated design. BMan1113VR 04:18, 5 December 2006 (UTC)

Perhaps this is a better picture:

File:Caterham CSR Rear suspension.JPG

(resized) BMan1113VR 11:25, 23 December 2006 (UTC)

Agreed. This article needs more pictures to illustrate modern car suspension systems. -- 193.211.5.90 (talk) 08:30, 22 November 2007 (UTC)

Automotive suspension design merge

Automotive suspension design seems redundant (or close to it) with this. I have suggested we merge it here. (John User:Jwy talk) 15:03, 23 February 2007 (UTC)

I disagree. One is about the process, the other is about the hardware. There again, I'm biased (since I design suspensions)! Greglocock 23:19, 23 February 2007 (UTC)

I guess redundant is the wrong word. Might it make sense to include the design information in a section here. (I didn't mean to dis your profession!) The design article is rather short. (John User:Jwy talk) 00:14, 24 February 2007 (UTC)

It was a requested article, so I created it, but it obviously included just enough information to escape being a stub. I'll expand it at some point. If you can make some suggestions on its talk page I'll gladly do that. Greglocock 00:42, 24 February 2007 (UTC)

okay. While I'm glad I have a suspension on my car, I'm not savvy enough about it to help much. I'll back off and check up after a while. (John User:Jwy talk) 02:59, 24 February 2007 (UTC)

Sprung Weight Transfer

A while back I contributed several sections based on years of engineering knowledge of vehicle dynamics and suspension design.

The discussion about Sprung Weight Transfer was changed so much as to make the entire discussion wrong. One major concept in SWT is the roll moment arm. This entire section was removed. The "helper" did not understand the concept and figured it was unimportant.

A drawing really should be added but I don't have the time now figure out how to add it.

The drawing needs to be a nicely drawn and added to the discussion. Here is rough drawing to help with the idea.

http://www.onthetop.com/images/weighttransfer.jpg

There needs to be a few others to clarify the ideas. —The preceding unsigned comment was added by Imfinenu (talk • contribs) 23:27, 30 April 2007 (UTC).

Top (or Bottom) links

I'm looking for somewhere to link 'top link' from the description of the rear suspension on the Brabham BT19. The rear suspension is described (in all sources) as a reverse lower wishbone (ie single link on the chassis side) with single top link and two trailing radius rods. Not an unusual design for that time. Exactly what the top link was doing in that little lot is a bit hard to tell, but I guess mainly controlling vertical movement of the top end of the uprights. Although top link is used quite a lot as a term in writing about cars of that era, the meaning is taken to be so obvious (it's a link at the top!) that it's never defined. Any ideas where in the range of suspension articles I could most usefully link this term? The set up almost sounds like a crude multi-link design.... 4u1e 14:44, 8 May 2007 (UTC)

Control Blade rear suspension

I'm looking for a good explanation, with pictures, of the famous Control Blade independent rear suspension used in the Ford Focus and the latest Mondeo, how it works and why is it (supposedly) better than ordinary multi link suspensions. Anyone care to help?

http://www.carbibles.com/suspension_bible.html - the pictures are good, the words are anywhere between wrong and unreliable. Sorry, I don't think anything has been published, why would it be? Greglocock 02:35, 13 July 2007 (UTC)

the words are anywhere between wrong and unreliable.

I'm afraid, in my experience, that applies to the majority of stuff written about vehicle suspension systems.

I'm not sure whether this enough to help with your query, but I can offer this much (some of which I have picked up from elsewhere, so see previous note, and it may be oversimplified for your purposes).

The Ford Control Blade suspension system is a system in which the behaviour of the rear wheels of the suspension system is changed from the geometrically orthodox in order to impart a degree of passive steer. That is, as the vehicle rolls in cornering, the geometric changes aid the vehicle in steering round the corner. There are a number of (potential) advantages to this approach:
- It can be used on a vehicle which has an inherent tendency to understeer in order to make it more neutral (understeer less or even oversteer, although most would not consider that an advantage in most circumstances)
- It can be used to contribute a degree of understeer compensation that decreases at increased cornering loads in order to maintain a basically neutral stance when the vehicle is driven at 'five tenths' but reverting to a 'safe but dull' understeering stance when driven at 'ten tenths'.
Note that these advantages are likely to be useful on a front engined, front wheel drive car. Note also that there are other measures that you take to counter understeer and I am making no comment about which measures would be best either in particular circumstances or generally. Yet another note: I am not going to write a wikipedia definition of 'ten tenths'.

There are also disadvantages
- Static suspension loads (e.g., a 'full boot') steer both rear wheels equally and increase the overall rolling resistance of the vehicle (actually you could set it up for minimum rolling resistance at full load and then it would deteriorate at low load, or vice versa. Note that full 'rear steer' systems do not have this effect.) As both rear wheels are steered equally if the deflections are equal, the effects on vehicle course cancel (except for split u surfaces...).
- The system is equivalent in some ways to bump steer and it tends to reduce steering accuracy (or the feeling of steering accuracy) on heavily textured road surfaces

You should also note that Ford is not alone in having such a system: At the very least, Volkswagen use a system which is similar in principal and for which they have their own brand name.

Mark w69 10:07, 5 October 2007 (UTC)

Mostly drivel. Greglocock 11:12, 5 October 2007 (UTC)

Contribution to unsprung weight and total weight section

I'm not sure what this is getting at. It is confusing as worded. There are several interpretations as to what they are trying to say...

"These are usually small, except that the suspension is related to whether the brakes and differential(s) are sprung."

The topic heading would seem to be about how suspension contributes to unsprung weight and vehicle total weight. But the information is far from meaningful, complete or informative. Maybe the heading should be Contribution to unsprung, sprung and total weight.

"These are usually small..." Not a true statement with respect to unsprung weight! Suspension accounts for the majority of the unsprung weight in most vehicles (60%-90%). Suspension accounts for a small part of the vehicles sprung weight and maybe as low as 10% of the vehicles total weight. But this is not clear and may be wrong the way it is written.

It is unclear if they are actually trying to state that "suspension" may refer to whether or not the brakes and differential(s) are sprung. (I personally have not heard it used this way.) If so, then the heading should be about the slang use of the word suspension. It should then also clarify that "suspension" is short slang term for "independant suspension" in the same way that "anti-lock" is often used as the short slang term for "anti-lock brakes" or "strut" for "Macpherson Strut" or "independant" for "independant rear suspension".

The part after the "...except..." would seem to be pointing out a case in which the contribution to unsprung and total weight is large. The writer doesn't mention whether or not they are refering to independant suspension or not or if they are trying to point out that in the case of non-independant suspension the differental and brakes will contribute a larger amount to the vehicles unsprung weight.

It may be restating parts of the beginning of section 2.4.1 in a confusing way.

If the meaning is to point out that a differential in an independant suspension is part of the sprung mass of the vehicle, the comment/note should be included within the discussion of sprung weight 2.4.1 and not it's own topic located too far from that area.

Since the meaning of the section is unclear to me, I will not change it. I will leave it to others to decide whether or not it would be best to modify/clarify, delete and/or add it to section 2.4.1.1. —The preceding unsigned comment was added by 75.17.129.85 (talk) 14:10, August 23, 2007 (UTC)

This is close to unreadable...

The main page (not the discussion page) is close to unreadable with poor grammar and confused sections. I want to re-write it, but I guess it would just get reverted by the original authors. Mark w69 10:45, 5 October 2007 (UTC)

Mark w69, as a contributer myself, I appreciate a careful rewording of my work. However, take great care to retain the contributer's ideas and meaning. Unless you understand the subject at least as well as the person that wrote it, leave it alone. One last comment about rewriting, be careful not to simply change things because the writer uses a style or terms common to their country. I have written areas on other topics and later had someone change a correctly spelled word using U.S. English to a European spelling. Wikipedia is a global resource and contributors should be welcomed from all nationallities points of view. However, when a contributor writes a word like "tire" as apposed to "tyre" it should be understood that the topic is written from a US point of view in contrast to a British point of view. Example: A contributor may be discussing a concept and uses an example of a European sportscar's tyre to illustrate his point. When a reader reads the passage it is clear what the point of view is. It would not be propper to change the spelling of tyre to tire in this case or change the BMW to a Corvette simple because of a preference of one's own nationallity.

Sorry, but this violates the Wikipedia policy of "Consistency within articles":

"Each article consistently uses the same conventions of spelling and grammar (e.g., British, Canadian); for example, center and centre are not to be used in the same article. The exceptions are:

• quotations (the original variety is retained);
• titles (the original spelling is used, for example United States Department of Defense and Australian Defence Force); and
• explicit comparisons of varieties of English."

-Wikipedia:Manual_of_Style#National_varieties_of_English

As contributors, it appears to be our job to see what spelling is used in an article and match it. -AndrewDressel 20:42, 14 October 2007 (UTC)

Points of view can differ because of differing design goals as is the case of European Rally Car suspension design vs U.S. Pike's Peak Run cars or perhaps Baja 1000 offroad suspension design. A Baja 1000 suspension designer would be much more concerned with suspension travel and traversing large road surface irregularities than ultimate cornering speed. Discussing using tire surface temperature distribution while critical to suspension alignment and tire pressures of a F1 car may be pointless to add to a discussion of tire compliance over extremely rough muddy or powdery courses seen in the Baja 1000 events. I don't think many people would have a problem with making improvments but make sure they are improvments and take extreme measures as to not eliminate a contributors ideas. Doing so may put off an expert from contributing further even if their grammer leaves a bit to be desired. —Preceding unsigned comment added by 75.17.129.85 (talk) 18:05, 14 October 2007 (UTC)