hydraulics expert needed

[barend]

I'm toying with an idea to use hydraulics to make my sidecar lean with the bike as opposed to the three control arms I currently have. Problem is, I don't know nearly enough to even begin addressing the subject. I know what I "want" but need some input to see if it is feasible. If you can help, let me know.

 

Thanks

[dingy]

Are you implying that you want an "Intelligent" system?

 

This would be something along the lines of a tilt controller that sensed lean of the bike then actuated a set of hydraulic or pneumatic actuators to control the bike to side car attachment angle. Something like this would take a fairly sophisticated control system. I would think some sort of gyroscopic unit would be required.

 

I would think that pneumatic system would be simpler than a hydraulic system. Control valves are smaller. It would be easier to find a pneumatic power system I believe that is compact enough. In general running supply lines is much easier than hydraulic.

 

Tilt angle could be controlled with linear sensing actuators. These give a feedback to the control unit, depending on precise amount of travel.

 

Would not be cheap.

 

Gary

[Cruser]

Actually it would be a very sophisticated system, even though the parts are available for such a system the expense would be huge.

 

simple limit switches can used to actuate the small rams that would be required, in hydraulics small is very expensive in comparison to some of the larger components.

 

I deal with hydraulics everyday, only on an industrial scale, but all of the parts are available to do what would be considered a miniature system.

 

1-12 volt pump it probably would not need to generate more than 25 psi to do what you want , 2-12 volt limit switches and 2 small cylinders a small storage tank, maybe a gallon in size.

 

positioning the switches will be the fun part the rest is simple fabrication. cylinder attach points, Number 4 hose and a few fittings it can all fit in an area of about 1 cubic foot of space.

 

cost some where around $1500.00 would be my experienced guess , I can look up the stuff for you if you want I can also get costs if you want to give it a shot.

[Cruser]

Are you implying that you want an "Intelligent" system?

 

This would be something along the lines of a tilt controller that sensed lean of the bike then actuated a set of hydraulic or pneumatic actuators to control the bike to side car attachment angle. Something like this would take a fairly sophisticated control system. I would think some sort of gyroscopic unit would be required.

 

I would think that pneumatic system would be simpler than a hydraulic system. Control valves are smaller. It would be easier to find a pneumatic power system I believe that is compact enough. In general running supply lines is much easier than hydraulic.

 

Tilt angle could be controlled with linear sensing actuators. These give a feedback to the control unit, depending on precise amount of travel.

 

Would not be cheap.

 

Gary

 

air is faster, the components are the same size for hydraulics, the main difference is durability and strength, hydraulics are much stronger and way more durable.

[MiCarl]

Why not do it with linkages? Cheaper, simpler, no power supply needed.....

[barend]

There is a system out there which uses D cams and chains, it seemed to me that using hydro (or air) would be a lot less bulky while saving weight. I had assumed that since fluid would be pushed both directions you would not really need a reservoir. I'm also thinking that you should be able to stop flow either direction and basically lock the system so that the unit cannot lean? how small is small on the cylinders?

 

I would be interested but at the price I suppose I should wait till my wife's got another job:whistling: Thanks for the info though, I'll keep this on the back burner and see if i can revive it at some point

[Cruser]

I can do some photo's as visual aides for component size.

 

hydraulics require a pressure relief valve which is the main reason for the reservoir, once the system is full its full but able to compensate for excess pressure on one side and a loss on the other the oil has to have some place to be displaced to. I may have exaggerated the reservoir size but your side car may require more than one cylinder per side to stabilise the lean for the whole length.

 

otherwise you have a closed system and more of a shock absorber which is not a responsive system but is more of a passive system if one shock becomes weak then the whole balance is thrown out and a constant lean of the car to one side or the other toward the weaker component is the result.

 

let me know if you want to go ahead with a plan for the system even if it's put on hold for a while. Good planning is a good idea.

[TNrider]

Why not just use a SLA suspension much like the older cars had on their front end. Sidecar would lean both directions then in accordance with the bike.

[Guest PlaneCrazy]

I'm toying with an idea to use hydraulics to make my sidecar lean with the bike as opposed to the three control arms I currently have. Problem is, I don't know nearly enough to even begin addressing the subject. I know what I "want" but need some input to see if it is feasible. If you can help, let me know.

 

Thanks

 

I can envision a system using a nose wheel steering actuator from an aircraft.

 

The way they work is there's a bidirectional actuator and a summing mechanism. When the pilot moves the tiller in the cockpit, he actually just moves a small lever on the actuator that is connected to a control piston inside the actuator . This causes the actuator to start to move in the direction that the arm went and as the actuator moves that way, a feedback link moves a control piston inside the actuator until a "null" zone is reached, bypassing fluid and stopping the actuator. Release the lever and the null is displaced, causing the actuator to start to move back, until the feedback link moves the piston back to the Null range.

 

The problem with a hydraulic system though is all the equipment you need. These steering actuators are pretty small actually, but you still need a power pak that's either electric driven or a pump on your engine. You also need a reservoir, pressure control and safety systems.

 

The advantages are that this system is completely hydro/mechanical... therefore no fancy electronics. And it's very reliable and strong. Real aircraft actuators would be prohibitively expensive, but there's more then likely many civilian equivalents (even power steering units in vehicles are very similar.)

[barend]

Had to look up and see what an SLA system is, looks very bulky. Right now I have about 20 inches between bike frame and sidecar, maybe another 6 to get to the wheel hub, unless they make something like this for a go cart this may not be a viable option.

 

It's been 20 plus years since I sat in a plane and most of what I flew was the tricycle gear variety, heck I can't even remember if steering was hydro or mechanical. and I used to be an instructor ...

 

and yes, I'd be interested in pictures (or links and part numbers), thanks.

 

also going to check and see if there is a trashed Flexit out there which obviously doesn't need the actuator anymore

 

Thanks guys!

[Cruser]

The actuators are called transmitters " its a technical sounding word that just means the oil is changed from one port to another mechanically" rather than electrically , they can be found in a very small package. most of the pumps that I use are powered by electric motors, I do have a few that are driven from chains but those originate with an electric motor that drives another system the power for the pump is just transferred from a different drive source.