Alternative use for shocks

[mschuf355]

Please excuse my post as it does not neccesarily have to do with r/c.

I am building a set of pedals to use with my PS2 and thought about using truck shocks as a damper/return mechanism for the accelerator and brake pedals. This is by no means a new idea as a number of folks have used them in a similar manner.

Check out http://www.bulletweb.de for an example.

My question is: Which shock, in your opinion, would be the best for this application?

Any help would be appreciated.

 

[GilBeQuick]

That all depends on how long you want your pedal travel to be.....

 

[RobH]

Pedal travel is relative to where you attach the shock to the pedal right? Putting a short shock close to the pedal hinge would give you the same pedal travel as putting a long shock far away from the hinge.

If you follow the link, he wants to do something like this:

if you can muk your way around the german, that site has a pretty awsome cockpit for PC racing games. Talk about getting way too into it....

Back on topic, good luck with your project. I don't know a whole lot about trying to do that. It seems like the weight of the shock oil would effect how quickly you can depress the pedal and the stength of the spring would effect how quickly it rebounds. I'm guessing that you'd want some fairly thin shock oil like 25wt or something and and the "stiff" shocks.

Guessing by the picture, I think he's using the front shocks off a buggy. If you dig deeper into his page, you'll see that he put the pedals on tracks:

are those ball ends and huge camber rods? cool stuff.

Have fun and good luck.

-RobH

 

[mschuf355]

The pedal design I am working on will be floor mounted vs a hanging design in the pictures from the bulletweb site. My pedals will also be using a more traditional rotating potentiometer vs the sliding one also shown in those pix.

Based on these two things, I will probably not need that much travel out of the shocks. I think the rotation on the pots is less than 90 degrees.

Immediately I should look for an adjustable, do you agree? That starts to narrow the field down... Integy is about all I've seen in an adjustable version.

Are all shocks oil charged, or are some gas charged? Again, I would think I need to look at oil charged for the ability to adjust the dampening.

Thanks again, guys.

BTW: If you think this guy at bulletweb had it bad, just go out to eracer garage (http://schooner.gotdns.com/eracer) and look at some of the other projects that are out there.

 

[RobH]

RC shocks are oil filled. It's up to the hobbyist to fill the shocks. Shocks oils come in different weights. A small weight (10-25wt) oil lets the shock depress rapidly. With a heavier oil (50-75), the shock from be able to depress very quickly. You can change the oil to your liking so in that respect they are adjustable.

The other thing you can adjust is the strength of the spring. Most shocks come with spacer or a metal collar that constricts around the body of the shock. You can then pre-load the spring and basically make it stiffer. The only downside is that you loose travel the stiffer you make it.

I wouldn't suggest using long springs. I think the force on such a small, long shaft would cause them to bend easy (they do bend with enough force). I short shock would also be bad because you wouldn't have much control and the adjustment you'd make would be dramatic.

What length are of your pedals?

-Rob

 

[mschuf355]

The pedals will probably end up being around 250mm. I'm looking at a number of different designs, so I can make the bracing system look any way I want it to. Here's the leading candidate, although I won't be making it out of billet aluminum!

http://www.apracing.com/car/cylinder/cp5500_1cd_iss20.pdf

You can see in the pdf file that the travel distance is really not that far. Don't get too caught up in the picture above, as that design barely provides enough room to squeeze in any kind of dampening.

Needless to say, I should probably focus on the "large bore" Traxx style shock, correct? So far I've seen the Traxxas, the Integy, and the Losi.

 

[RobH]

Take a look at these these:

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXANU0&P=7

They are four inches long where your pedals are 10 or so inches long. These may work.

I'm not a shock expert or much of even an expert in general. I'm just trying to use some logic and help you brainstorm on ideas. I don't think anyone in this forum has ever done what you're trying.

If it were my project, I would just go pick up some shocks and try it. I like to use educated guesses and then ultimately fly by the seat of my pants. :shrug:

Good Luck,
Rob

 

[nl2377]

heh, a whole 90 degrees... lets hope you have some sort of pulley system connected there... otherwise we are talkin about a pedal depressing the whole 90 degrees... good luck man...