Project AntiRoll - Prototype linked RC suspension system

[Enderman]

PROJECT: ANTIROLL

By Enderman

Start Date: April 11, 2016

 

Abstract

This project is a concept prototype of a linked suspension system to remove the necessity of sway bars in high speed RC vehicles.

 

 

 

Table of Contents

Subject:                                                                            Page:

Table of Contents ……………………………………….…........ 1

Introduction …………………………………………………....... 1

Concept …………………………………………………....…..... 1

Parts List …………………………………………………......…. 1

Pricing ………………………………………………….....…….. 1

Renders …………………………………………………......….. 1

Explanation of fluid to be used.............................................. (upcoming)

Build Process (part 1).……………………………….......…… 1

Results ................................................................................. (upcoming)

Conclusion ........................................................................... (upcoming)

 

 

 

Introduction

A linked suspension system is a simple idea to remove the need for sway bars, patented in 2003. The concept behind it is that by cross-linking two hydraulic pistons bottom to top, the rods will remain at the same height. This is useful for high speed vehicles that have body roll when cornering. Linking the left and right sides of the suspension together helps keep the vehicle level and well planted. Since this concept will be tested on a RC car, the pistons necessary will be very small. This could lead to flow restriction, so the first tests will be done using compressed air, and if unsuccessful then light shock oil will be used. The damping rate of the shock can also be adjusted by changing the flow rate of the air in the tubes with an adjustable valve. This will give a similar effect to that of regular RC shock with shock oil. A visual description of the concept will be provided on the next section.

 

 

 

Concept

High speed cars require sway bars to corner at high speeds properly and to minimize chances of a flipped vehicle. This project aims to replace sway bars with pneumatic pistons embedded in the socks.

 

Image credit: http://site.petitrc.com/Tech/XRC_TuneWithSwayBars_files/XRC_TuneWithSwayBars.htm

The top chamber of one piston is connected to the bottom chamber of the piston on the other side of the vehicle.

 

 

 

The air pressure is equal in both tubes and pistons. The two pistons have their shafts at the same length when filled.

 

 

 

When the outside piston becomes compressed by vehicle body roll, the inside piston lifts up as well, causing more of the vehicle’s weight to rest on the outside wheels. This increases traction and improves turning at high speed.

 

Air/fluid pulls and pushes this piston up at the same time.

 

 

This pairing of pneumatics will have some additions to the tubing lines for control, see below:

 

Fill ports (gray)

Air pressure control valves (white)

 

 

The air pressure control valves will reduce the air speed flowing through the tubes to slow down the piston compression, adding a dampening effect to the shocks. The fill ports will be used to pressurize the pistons to decrease air compression and simulate the effect of a non-compressible fluid.

 

 

 

Since the pistons are free to move upwards and downwards, just the pneumatics alone will not provide any shock absorption. RC coil-over shock springs will be used similarly to regular shocks for the regular purpose. Due to the lower chamber calves being near the bottom of the pneumatic, the shock springs will not span the entire length of the shock, but rather just the bottom portion of the piston rod. Thin wire springs should still give the shocks near 100% stroke length, and softer springs can be used to compensate for the larger than normal compression.

 

 

 

Thanks for reading! Stay tuned for the next updates coming soon.

[airdeano]

valued concept.

when i was racing (1990-1998) 1/10th scale off-road (jrx2) we'd 'sperminted' with a similar concept and found the effort possible (as full hydraulic no air in the system).

 

issues:

finding the perfect viscosity oil for the shock for suspension control and allow the sync transfer to happen was difficult.

once you found the 5/5-10/10wt oil for reaction, the overall spring had to be softer (causing bottom-out) on mid height jumps or succession ripple/rib washouts.

stiffer springs made the action-side 'bounce'. even changing to different pistons, one-way valving, dual pistons, etc.. the balancing just couldn't be found. found the better cutting tire/caster/camber and toss the swaybar (limited wheel jumping travel) and cross-shock hydraulics.

 

for open-wheel dirt oval, this was a better plan. using off-road tires (long travel) this was a better way to control body roll.but, using foams/RTV caps/rubber caps a shorter shock travel was more advantageous, and again, using caster/camber and rollout over bars and cross-hydraulics.

if rules permitting, using a max-sized side dam, 90/10RF, 70/30LF, 50/50 rear always made for a starting point on all ovals (dirt/asphalt) no sway bars. bars always compensated for an ill-balance of suspension or extreme hi-center of gravity. even when racing the dominators (on velodromes), the bars always over-accented the push/loose in either early entry of corner or late exit (pitchy/snap loose).

 

road course is where this was best used. on full-suspension asphalt buggies we'd found the loosest 3-h .100" pistons 30wt oil worked well with the suspension not tied down.

tried using from .045" to .090" wire for bars front and/or rear (restricted the wheel travel). the cross hydraulics worked out well, but the shocks deffo had to be rebuilt quite often.

 

good luck, we could not get a best point of satisfaction using this system.

raced:

4min off-road, dirt oval, paved oval, parking lot asphalt, carpet, roller rink floor, concrete velodrome, tiled concrete floors, indoor basketball court.

[Enderman]

2 minutes ago, airdeano said:

valued concept.

when i was racing (1990-1998) 1/10th scale off-road (jrx2) we'd 'sperminted' with a similar concept and found the effort possible (as full hydraulic no air in the system).

 

issues:

finding the perfect viscosity oil for the shock for suspension control and allow the sync transfer to happen was difficult.

once you found the 5/5-10/10wt oil for reaction, the overall spring had to be softer (causing bottom-out) on mid height jumps or succession ripple/rib washouts.

stiffer springs made the action-side 'bounce'. even changing to different pistons, one-way valving, dual pistons, etc.. the balancing just couldn't be found. found the better cutting tire/caster/camber and toss the swaybar (limited wheel jumping travel) and cross-shock hydraulics.

 

for open-wheel dirt oval, this was a better plan. using off-road tires (long travel) this was a better way to control body roll.but, using foams/RTV caps/rubber caps a shorter shock travel was more advantageous, and again, using caster/camber and rollout over bars and cross-hydraulics.

if rules permitting, using a max-sized side dam, 90/10RF, 70/30LF, 50/50 rear always made for a starting point on all ovals (dirt/asphalt) no sway bars. bars always compensated for an ill-balance of suspension or extreme hi-center of gravity. even when racing the dominators (on velodromes), the bars always over-accented the push/loose in either early entry of corner or late exit (pitchy/snap loose).

 

road course is where this was best used. on full-suspension asphalt buggies we'd found the loosest 3-h .100" pistons 30wt oil worked well with the suspension not tied down.

tried using from .045" to .090" wire for bars front and/or rear (restricted the wheel travel). the cross hydraulics worked out well, but the shocks deffo had to be rebuilt quite often.

 

good luck, we could not get a best point of satisfaction using this system.

raced:

4min off-road, dirt oval, paved oval, parking lot asphalt, carpet, roller rink floor, concrete velodrome, tiled concrete floors, indoor basketball court.

That's really cool

I considered oil but there are no mini hydraulics, only mini pneumatics

Technically I should be able to use oil in them, if the seals hold back air then they will also hold back oil, the only problem I see is that the inlet ports are very small (4mm) and would cause a lot of restriction unless I used a very light oil

 

First I will try with compressed air (since regular air wouldn't provide the fluid effect) with the air control valves for dampening

If that doesn't work I will try light oil

 

 

Another thing I just considered was instead of using coil over springs, having a piston in-line of one of the tubing runs, and having a spring on that piston to hold the shaft. Then all the spring "suspension" will be provided by air/fluid pressure instead of having springs on each piston

 

But that will be a second part to this concept if get this thing working

[Made In Canada]

TLDR; Where do you come up with this stuff?

[Enderman]

4 minutes ago, Made In Canada said:

TLDR; Where do you come up with this stuff?

uh, i just came up with stuff randomly

things I want to build and improve, so I look for ways to do so

 

Unfortunately someone already patented this, since its a pretty simple idea, but I will come up with more ideas

[airdeano]

what we'd looked to do was to have a 'control' chamber/bladder via interior of the shock tube .625"-.750" instead of the conventional associated/losi shock bodies. the associated had a better action, but the losi were more consistent. making the shaft packing was being the 'turd' for the completion.

 

the bladder could use a different 0wt/5wt oil as the roll control aspect and the rest of the tube then could utilize the normal thicker viscosity oils for suspension control. another was to use a remote reservoir like the off-road motorcycles use and use that for the roll control as remote.

[Made In Canada]

1 minute ago, Enderman said:

uh, i just came up with stuff randomly

things I want to build and improve, so I look for ways to do so

 

Unfortunately someone already patented this, since its a pretty simple idea, but I will come up with more ideas

Engineer-ative (paten that as a new word).

 

To more ideas!

[Made In Canada]

3 minutes ago, airdeano said:

what we'd looked to do was to have a 'control' chamber/bladder via interior of the shock tube .625"-.750" instead of the conventional associated/losi shock bodies. the associated had a better action, but the losi were more consistent. making the shaft packing was being the 'turd' for the completion.

 

the bladder could use a different 0wt/5wt oil as the roll control aspect and the rest of the tube then could utilize the normal thicker viscosity oils for suspension control. another was to use a remote reservoir like the off-road motorcycles use and use that for the roll control as remote.

tas yo quibd sjduqwgdi qwerty uiop jiln nef qwhigvbqyweuifge wduibdidogbiuydegeg wiwq qjwbdiqouoifjgoodfsnm wdfcobdfn.

 

I could not understand your comment either. <insert dont ban me face here>

[Enderman]

9 minutes ago, Made In Canada said:

tas yo quibd sjduqwgdi qwerty uiop jiln nef qwhigvbqyweuifge wduibdidogbiuydegeg wiwq qjwbdiqouoifjgoodfsnm wdfcobdfn.

 

I could not understand your comment either. <insert dont ban me face here>

RC talk

[Enderman]

32 minutes ago, airdeano said:

what we'd looked to do was to have a 'control' chamber/bladder via interior of the shock tube .625"-.750" instead of the conventional associated/losi shock bodies. the associated had a better action, but the losi were more consistent. making the shaft packing was being the 'turd' for the completion.

 

the bladder could use a different 0wt/5wt oil as the roll control aspect and the rest of the tube then could utilize the normal thicker viscosity oils for suspension control. another was to use a remote reservoir like the off-road motorcycles use and use that for the roll control as remote.

By the way, what did you use for the shocks?
Did you drill holes in them and attach tubes or did you buy real pneumatic or hydraulic cylinders?

[Made In Canada]

19 minutes ago, Enderman said:

RC talk

Really?

 

It could have been an alien species talking through LTT. Well guess we can blame aliens next time... Orrrrr southerners, cant understand either of them, at least aliens might be able to use music...

 

( @airdeano I would not say arkansas is as southern as i am talking about even though it is somewhat southern according to the US map).

Edited April 18, 2016 by Made In Canada
Words And Please Dont Ban Me

[airdeano]

for the start, we used off-the-shelf losi shock bodies. then losi came out with the long tube bodies for the truck classes. we ended up modifying 1/8 scale shocks and ran into the same issues of the transfer tubing was microscopic (having to use the thin weighted oils). thats when we started to look to a remoted system.

but then it all was adding extra weight 4oz per shock used and we were always weight conscious. but we were able to increase the ID of the transfer tubing to 5.5mm (woot).

[Enderman]

4 minutes ago, airdeano said:

for the start, we used off-the-shelf losi shock bodies. then losi came out with the long tube bodies for the truck classes. we ended up modifying 1/8 scale shocks and ran into the same issues of the transfer tubing was microscopic (having to use the thin weighted oils). thats when we started to look to a remoted system.

 

but then it all was adding extra weight 4oz per shock used and we were always weight conscious. but we were able to increase the ID of the transfer tubing to 5.5mm (woot).

Thanks

those are some pretty beastly shocks lol

 

I'm not gonna be using regular shocks, so we'll see how it turns out

I'll post the parts list soon

[straight_stewie]

How does this affect the shocks ability to actually flex and handle rough terrain? It seems to me if the suspension is permanently and always linked then when one tire hits a rock, both shocks will be lifted. This will slow down the vehicle in rough terrain.

[Enderman]

5 minutes ago, straight_stewie said:

How does this affect the shocks ability to actually flex and handle rough terrain? It seems to me if the suspension is permanently and always linked then when one tire hits a rock, both shocks will be lifted. This will slow down the vehicle in rough terrain.

You can adjust how much the second shock lifts based on the air pressure that will be inside, since air can be more or less compressible

If you're going over rough terrain you usually dont want sway bars, especially for rock crawlers

 

Sway bars are more for race vehicles for paved or dirt tracks

[Enderman]

Parts list

The most important - and expensive - parts for this project consists of mini pneumatic cylinders. These cylinders are several centimeters long and can handle up to 160psi or 1Mpa. To replace the shocks in the RC car, two different sizes will be needed. Both pairs of pneumatics will have a 16mm bore, but two rear shocks will have a 25mm stroke while the two front ones will have a 20mm stroke. Each 25mm pneumatic costs $14 and each 20mm pneumatic costs $12. The total cost for both pairs will be $52 CAD.

https://www.amazon.ca/Stroke-Single-Double-Action-Cylinder/dp/B008AGMBSA/ref=sr_1_15?ie=UTF8&qid=1459919999&sr=8-15&keywords=Mini+Pneumatic+Cylinder+25mm

https://www.amazon.ca/16mm-Stroke-CDJ2B-Pneumatic-Cylinder/dp/B008MNJFFS/ref=sr_1_1?ie=UTF8&qid=1460425601&sr=8-1&keywords=Pneumatic+16mm+Bore+20mm+Stroke

 

To attach the two penumatics together 4mm OD 2.5mm ID tubing will be used. This tubing comes in several colours but the clear tubing is preferred in case shock oil is used instead of air. It would be beneficial to see the fluid inside the tubes to easily find and extract air bubbles. A 5m length of tubing costs $4 CAD.

https://www.amazon.ca/uxcell%C2%AE-Meter-16-4Ft-Pneumatic-Transparent/dp/B00K81AU2Y/ref=sr_1_8?ie=UTF8&qid=1460425541&sr=8-8&keywords=pneumatic+tube+4mm

 

To connect the tubing the the pneumatics, small M5 barbs for 4mm tubing will be bought. The barbs are less bulky than quick connect fittings, and this will help fit the tubing in the small area that is available on the RC car. A pack of 10 barbs costs $5 CAD.

https://www.amazon.ca/10Pcs-Male-Thread-Pneumatic-Fittings/dp/B00P3FSXUG/ref=sr_1_3?ie=UTF8&qid=1459888570&sr=8-3&keywords=4mm+fitting+for+pneumatic

 

Air at atmospheric pressure is very easy to compress. The fluid inside the pneumatics must be very incompressible to have an anti-roll effect when linked together. For this reason the air inside the pneumatics will be compressed with a bike air pump, and different pressures will be tested. To insert compressed air into each set of pneumatics, a T joint must be added to each tubing line. A pack of 10 T joints for 4mm tubing costs $5 CAD.

https://www.amazon.ca/10Pcs-Connector-Pneumatic-Style-Fittings/dp/B00HR824KC/ref=sr_1_2?ie=UTF8&qid=1460419732&sr=8-2&keywords=pneumatic+t+4mm

 

In order to prevent the compressed air from escaping the tubing after being filled, a shut off valve is necessary. One valve for the front pistons, and one for the rear. A pack of two valves costs $6 CAD.

https://www.amazon.ca/Quick-Connector-Pneumatic-Speed-Control/dp/B00NQ4QLRS/ref=sr_1_30?ie=UTF8&qid=1460420160&sr=8-30&keywords=pneumatic+4mm+valve

 

The final piece is an air speed valve to control the flow of air between pistons. This will give a dampening effect to reduce the speed of the pistons collapsing by restricting airflow between the pistons. A set of three valves costs $5 CAD.

https://www.amazon.ca/Pneumatic-Quick-Adapter-Speed-Controller/dp/B00HG7GYQE/ref=sr_1_23?ie=UTF8&qid=1459888888&sr=8-23&keywords=pneumatic+valve+4mm

 

 

 

 

Pricing

Currency:	CAD
25mm stroke pneumatics	$14 x2 = $28
20mm stroke pneumatics	$12 x2 = $24
4mm OD 2.5mm ID tubing	$4
4mm M5 barbs	$5
4mm T joints	$5
4mm shut off valves	$6
4mm control valves	$5
Total cost:	$77

 

 

 

The total price fits a very good budget at less than $80 for all components. The shipping costs for all the items is free, making this concept prototype even more affordable. Several parts come in sets of 10 even though only 4 are necessary, so if more prototypes are to be built in the future the overall cost can go down.

 

 

 

Thanks for reading! Stay tuned for the next updates coming soon.

 

 

 

[Enderman]

Renders

Done with Sketchup Make.

 

Extended:

Retracted:

With added flow control valves/fill ports (which may or may not be used in the final prototype):

With highlighted compartments of fluid:

And finally with the springs in position:

Note that due to the position of the barbs, a coil-over spring is not possible. Shorter and stiffer springs will need to be used instead.

 

 

Update

 

So I have all the parts and will post build pictures soon, but two of the pneumatics did not arrive and must be lost in mail.

Those two are the front 20mm stroke pistons, so even though I can complete the rear suspension, real world tests with both front+rear antiroll suspension will need to wait about a month or two :C

 

[Enderman]

The Build

 

 

So I didn't take many progress pictures since I built it on camera, but the rear pneumatics are in place!

 

 

 

 

As you can see, I used some tubing clamps that fit perfectly around the cylinder to screw into my shock tower.

This nicely hold the piston in place, and at the correct height.

It is also possible to loosen and adjust the piston for lowered ride height.

 

 

I may add some material between the clamp and the piston because I have noticed that sometimes the piston slides up a bit since it is metal on metal.

 

To attach the bottom to the A-arms of the car, I used some pieces of metal (meant for hanging picture frames) and bent them around the piston shaft.

Then I used a screw to go through the hole and into the A-arm.

 

 

Very good strength for a thin piece of metal, but we will have to see how it holds up when running the vehicle.

 

 

50% finished!

 

 

Now it is time to wait for my other 2 pneumatics to arrive :C

But so far, testing by hand, definitely shows that the concept works (at least on the rear part of the car)

 

Video of everything up to this point so far:

 

Thanks for reading!

 

[pagani123]

@Enderman is there any advantages to this kind of system that would displace the disadvantages in price and (relative to a passive swaybar) complexity 

[Enderman]

21 minutes ago, Maybach123 said:

@Enderman is there any advantages to this kind of system that would displace the disadvantages in price and (relative to a passive swaybar) complexity 

well complexity is actually less than a sway bar, because you completely remove the need for the 3 moving components and six joints of the sway bar by incorporating the body roll reduction right into the shocks

 

When you consider the fact that my RC shocks cost $50 per pair, and this project cost $80 total, the cost is in fact less!  This system includes both shocks+sway bar in a single package

 

Of course if instead of using cheap pistons from china I used some higher quality hydraulics (similar to my RC shock's quality) it would probably cost over a hundred $

Unfortunately I haven't found any RC-style shocks that can be used as double acting pistons

 

So in the end, if some company could make RC shocks that function like a piston/hydraulic, the cost would be very similar and complexity would be less with only needing 2 tubes instead of 3 moving parts that sway bars have.

 

But other advantages would be

-larger/more durable shock shafts (the pistons are almost 2x as thick as my rc shocks!)

-tuning (you can try using different fluids and pressures to adjust car performance, which people love to do)

-looks (who doesn't think tubes are cool?)

-innovation (because trying new things is always awesome!)

[jet224presents]

i have a question what is the effectiveness of this compared to independent suspension or is it in a totally different class.... also if this is for rock crawling wouldn't the risks of pivoting the wheels put unwanted stress on the tire and most likely cause them to wear quicker? seems to be a good idea keep up the work

[Enderman]

3 minutes ago, jet224presents said:

i have a question what is the effectiveness of this compared to independent suspension or is it in a totally different class.... also if this is for rock crawling wouldn't the risks of pivoting the wheels put unwanted stress on the tire and most likely cause them to wear quicker? seems to be a good idea keep up the work

I found that it works better than the sway bars typically on the cars.

I assume this also applies to real life sized cars, since mclaren uses it in their sports cars instead of sway bars.

 

This isn't good for rock crawling though, for rock crawling you want independent suspension at each wheel to keep all the tires on the ground regardless of what shape the rocks are or position the vehicle is in.

This hydraulic/pneumatic linked suspension system is exclusively for road use.

[jet224presents]

Just now, Enderman said:

I found that it works better than the sway bars typically on the cars.

I assume this also applies to real life sized cars, since mclaren uses it in their sports cars instead of sway bars.

 

This isn't good for rock crawling though, for rock crawling you want independent suspension at each wheel to keep all the tires on the ground regardless of what shape the rocks are or position the vehicle is in.

This hydraulic/pneumatic linked suspension system is exclusively for road use.

cool thanks, if affordable it would definitely be a option for higher tier vehicles who don't want regular sway bars but a better option all together 

[RollTime]

You know, I can't tell what it is... but something about this post unnerves me.