solenoid or pneumatic shifter

[sahil_tu]

solenoid or pneumatic shifter?
which one is more reliable.???

i firstly preffered solenoid and searched for it but then i read somewhere that solenoid shits are not reliable and give problems in shifts.

can somebody enlighten me???

[sahil_tu]

solenoid or pneumatic shifter?
which one is more reliable.???

i firstly preffered solenoid and searched for it but then i read somewhere that solenoid shits are not reliable and give problems in shifts.

can somebody enlighten me???

[Simon Dingle]

Searching for the term "solenoid shifter" gets 27 hits on this forum.

Searching for the term "Pneumatic shifter" gets 80 hits on this forum.

I would imagine that most of the differences have been discussed in these topics.

However, in case it's not covered in one of those topics, I can confirm that solenoid shifting becomes unreliable if your battery voltage drops below a certain level.

[Mehul Botadra]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Simon Dingle:
Searching for the term "solenoid shifter" gets 27 hits on this forum.

Searching for the term "Pneumatic shifter" gets 80 hits on this forum.

I would imagine that most of the differences have been discussed in these topics.

However, in case it's not covered in one of those topics, I can confirm that solenoid shifting becomes unreliable if your battery voltage drops below a certain level. </div></BLOCKQUOTE>

Lol!

Solenoid eats up a lot of battery, we used a single battery just for the solenoid. Pneumatic eats lesser if you use electro pneumatic valves which should be the case, but you have a huge air tank then!

[Wagz]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Mehul Botadra:
Lol!

Solenoid eats up a lot of battery, we used a single battery just for the solenoid. Pneumatic eats lesser if you use electro pneumatic valves which should be the case, but you have a huge air tank then! </div></BLOCKQUOTE>

Just curious, what size battery did you add for the solenoid? Mass? Does it run in parallel with your main battery/get charged while driving? Or, of a different voltage? The only reason I've considered switching to full electric over pneumatic is to get away from having the compressed air tank. Its not fun trying to find a spot for the tank which fits the rest of the package/is easily mountable, passes rules, keep cg low, and doesn't overheat/release its contents. I am quite impressed with the performance of compressed air though. Solenoids/valves take ~22ms to open, and the pistons move fully in under 150ms when both clutch and shifter are being actuated at the same time.

And to add on to what Simon mentioned for solenoids, I can confirm that pneumatic shifting becomes unreliable if your air pressure drops below a certain level (think lim psi-&gt;0 of f(tank)).

[Mehul Botadra]

^^^
I think it was a normal car battery since we didnt have the cash to buy Li-ion. It was actually something smaller than a car battery and we had plugged it into the recharge circuit and it worked pretty good.

We can use pneumatic because its a little difficult to get compressed air of a particular pressure here in India. I thought of scuba diving tanks, but that happens at a Union Territory and will take us just 10 days to get to that place! http://fsae.com/groupee_common/emoticons/icon_smile.gif

[The_Man]

The solenoid shifter is power consuming but most of them are designed for motorcycles, so it is the same engines and battery and they run well in parallel with the main battery. It needs to be charged while driving because you are drawing 30-35 A for short durations. You do get 24V options but then it is a problem charging these on board. These are light as compared to pneumatic systems at 2-2.5kg overall.

Also, compressed air is not so difficult in India. For a shifter a scuba diving tank is really not required. Paint ball gun tanks are the closest if you do not want to use stock pneumatic shifters available. Most cycle shops have compressors that can do 400-500psi (Also not to expensive to buy) so exact pressure should not be an issue.

[JasperC]

We have very seriously looked into changing from a pneumatic (CO2 actuated) to a solenoid shifter last year, but we decided against it in the end.

The reason why we wanted to switch was that we had two problems with the pneumatic system: 1/ clutchless downshifting very often didn't work and 2/ sometimes the pressure regulator would "mysteriously" get stuck at a too low pressure.

In the end, there were a few reasons why we didn't change.

First of all, the downshifting issue wasn't due to a lack of shifting power but because our fuel cut caused us to brake on the engine ridiculously hard. So using a different system wasn't going to solve that problem, we just needed to figure out some tricks to make downshifting easier.

Second, the "mysterious" pressure regulator problem was simply the regulator being exposed to too much heat. Mounting the vessel at a cooler spot did the trick for us.

(A nice anecdote to throw in in between: at FS Germany the scrutineers told us we had to move the pressure vessel somewhere else, so it ended up at a hotter location in the end. We had to quickly come up with a solution for this so we ended taping and tie-wrapping a wet towel around the regulator and re-scrutineered that. So we drove the entire competition with a wet towel in our car otherwise we couldn't shift properly. That towel still has a special place somewhere in our workshop. http://fsae.com/groupee_common/emoticons/icon_smile.gif)

Third, we didn't manage to design a full electric shifting system that would do reliable clutchless shifts at a lower weight than our pneumatic system. We were looking at a solenoid weighing a few kg's which is simply too heavy.

Fourth, while it is true that packaging a pressure vessel is quite difficult, packaging a solenoid isn't that easy either... Mounting it directly on the shifting lever would mean we had to move the engine up, which was obviously a no-go.

And finally, those solenoids are bloody expensive...


To wrap things up, it has been proven by many teams that it is possible to have an excellent shifting system, be it pneumatic or electric. As in many cases, whether or not your shifter will work does not depend on the choice you make, but on how well you execute your choice. In my opinion.

Best regards,
Jasper Coosemans
Chief Drivetrain 2009-2010

DUT Racing Team
Delft University of Technology