Gear shift Efforts

[ravi27490]

Hello all,

I am Ravi from UM-Dearborn. I have a question regarding the Gear-shifting efforts for sequential manual transmission engines(r6,cbr)etc.

The teams using manual transmissions, can you guys let me know what is the torque to be applied to the gear shift lever to shift up and down at different engine speeds.

Thanks in advance.

-Ravi

[Swiftus]

Almost zero if you time it correctly. Up to infinity if you time it incorrectly.

HTH - Jay

[ravi27490]

Thank you for your reply Jay.

it cannot be 0 right... Lets say, we have a gear shift lever length of 2 inches. we are doing a 1-2 up-shift at 9000 rpm(with ignition cut-off of course-kinda clutch-less shift).
I want to know the force required at the lever end to make the gear shift.

I know it depends on the timing as well. Lets assume that the gear shift is completed between the start and the end of ignition cut-off.
What could be the force required to do this kind of gear shift?

Thank you.

[Swiftus]

It can be zero in exactly the right conditions. Most motorcycle engines - or nearly all - are not designed to see anything more than 0.5, maybe 0.7 lateral G. And most of the shift drums are set up with their axis laterally. In an FSAE car where you can easily shoot up past 2.5G momentarily, there is now 5 times the amount of force pushing the shift forks in a direction than the device was designed to handle. If the gear is right and the Gs are high enough, the transmission might be capable of shifting itself.

And that is just one of the numerous ways a sequential box can shift itself.

But, to answer your question, I can't remember the exact torque but I know I can grab the shift arm shaft on our engine with my hand and shift the transmission if I rotate the crank. So maybe 20Nm of torque?

[Mitchell]

The best way to understand the shifting forces are to go and take a motorbike for a ride, or ask someone who rides.

[Jay Lawrence]

Or grab your own engine and yank on the shifter with a fish scale

Either way, don't design it for minimum shift force

[ravi27490]

Thank you everyone for your replies.
I was an avid motorcycle rider back in india.
Thing is, every motorcycle transmission is different. I used to ride a Royal Enfield, which had a very bad gearbox. The gear shifter used to travel like a lot(about 150mm vertical travel at the tip of the lever). and it took a lot of effort to shift
I rode my buddy's KTM RC390 couple of times, and the shifter was having a very positive feel. The travel is not too long, the shift effort was not too high. Its just bang on perfect.
Even Yamaha's gearboxes shift really well. But thing is,

I was actually looking for some objective data and numbers if any one has done testing on the gearbox(any engine) for the development of electronic/pneumatic shifter mechanism.
If you have any names/brands of the shifters and the data sheets of them, please do share.

Jay, about the impact of lateral acceleration on the gear shifter, I am still not convinced greatly that the shifter drum would rotate itself at very high G's.
The transmissions always have a ratchet and Pawl mechanism, which is spring loaded. The spring force will be definitely a generous amount to prevent the gears to shift themselves.
Can you let me know if you guys had this kind of behavior in your car?Any data will be highly appreciated.


Thank you.

[BillCobb]

Judge "A" will expect you to present charts and analysis showing measurements of various linkage arrangements, shifter types and driver wrist torque expectations. If you get judge "B", they will focus instead on why your front wing is painted silver.

Teams that succeed probably will not be willing to share their secret applications of Lairup to the shifter parts, synthetic personal lubricants in the motor/transmission, and the use of a stun gun on the driver's arm as an aid in shifting during the autocross.

Now, let me direct you to the problems of having steering effort maximum limits that contribute to a winning car...

[ravi27490]

Hi Bill,

Thank you for your generous reply. I understand that the competition is between teams and the team with best overall performance wins.

I know the teams are not gonna share the design secrets, and ideally, they should not too.
It should be up-to the knowledge and good eye of a person, to identify the unique things done by different teams, and implement them if its good and appropriate for his own application.

In this context, I was not asking for the whole design of the gear shifter mechanism.
I was just looking for some objective data of the torque(read force along with a lever) required to do a gear shift, for which I got some decent feedback from Jay.(Thanks man!!!)

Can you guys let me know what brand of gear shifters you are using for pneumatic/electronic shifters?

I'm already googling a few, but would like to know good/bad reviews about specific brands/models.

Thank you.

[onemaniac]

I'm very certain most teams with electronic shifters design/ make their own system.
Also, I wonder what makes it so difficult for you to go test the required torque by yourself.
And if you're the one in charge of designing this system, your team's technical lead or whoever in charge of the overall engineering is not doing his/er job.
If the team had designed a good manual shifter to begin with, you guys must have recorded such basic design parameter somewhere.
For that reason, something tells me your team may be lacking documentation skills and your car certainly does not need more complication.

[P^squared]

Why move away from the CVT ?? !!

[Dunk Mckay]

Ravi, there are a number of relatively inexpensive power shifters out there, available for direct mounting to stock bikes. Find one that is compatible with the engine you are using and fit that.

I'm assuming you will be running an ignition cut for your shifts, in which case you will have more success with a solenoid type system (heavier but pretty much guarantees you will shift).

If you're using the clutch to shift then you should just use a mechanical linkage for shifting, not a power shift system.