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RPM trigger wheel

(@six_shooter)
Member

So, we're getting closer to getting our Land & Sea dyno in the ground and running. We got the main unit in the shop tonight, and were able to take a good look at it.

This particular unit uses an over driven secondary shaft to mount the brake with the strain sensor attached to it. We'll be making an arm off the brake to attach the load cell, just haven't figured out the exact layout yet.

Now originally I had thought that the trigger wheel (Supplied from YourDyno, so 30 teeth) would be attached to this secondary shaft. However, after some thought and given the gear ratio (3.214), that would have a tooth count of 96.42 per drum revolution, which I don't think will work correctly. So am I correct in assuming that the RPM wheel should be attached to the drum shaft directly, instead, or does it matter? We'll be using this as an inertia dyno at first, until we source and install a water pump and get the brake side working, I only mention that if that will have an effect on where the trigger wheel should be installed.

I assume this won't affect the way the YourDyno software to control the water brake (once it's working). since it will only be looking at the RPM input and won't care that it's not the same speed as the brake shaft, correct?

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Topic starter Posted : 03/12/2021 7:00 am
(@six_shooter)
Member

Anyone?

I looked in the manual and the wiki and didn't see anything that mentioned this specifically.

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Topic starter Posted : 05/12/2021 7:15 pm
(@admin)
Member Admin

Hello,

Apologies, I missed your message. 

The trigger wheel shall be on the same axle as the brake. If this is not possible, then you need to calculate the effective tooth count on the brake axle and enter this value. For example if the trigger wheel is mounted such that it spins 3 times faster than the brake, then enter 90 pulses for a 30 tooth wheel. The Pulses per revolution accepts decimal numbers. 

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Posted : 07/12/2021 11:08 pm
(@six_shooter)
Member

So even when not using the brake itself, using the dyno in inertia mode, like we will be doing until we can source a proper water pump, the trigger wheel on the driven axle, shown in my picture I attached will be fine?

Mounting the trigger wheel to the driven axle is not an issue, we have a plan for that, along with how to attach it to the drum axle as well. The work will be 6 of one, or half a dozen of the other.

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Topic starter Posted : 08/12/2021 12:11 am
(@admin)
Member Admin

When a dyno is in inertia mode, it still matters where the trigger wheel is placed. But it only matters in terms of the effective MOI. Move the trigger wheel and you will need to recalculate/re-measure the MOI. It also impacts the gear ratio of course.

 

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Posted : 11/12/2021 12:40 pm
(@furntrattrene)
Member

@admin 

Hello Guys!

I have the YourDyno Software now ca 3 Montas. I like it reallye but when i set the Gear ratio with the Motor RPM correct by 2000U/min and i make a run it is by RPM 4000U/Min not 100% correct. 

I think it is because i have a 44 teeth triger wheel. But i think it bekoms enoth Impuls 

I drive on a Bosch FLA 203 Dyno. 

When i make a run it has deviations of approx 5-10kw.

Need i make the MOI Setup every run or just every car?

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Posted : 11/12/2021 7:36 pm
(@furntrattrene)
Member

@Administrator 

Hallo Leute!

Ich habe die YourDyno Software jetzt ca. 3 Montas. Ich mag es wirklich, aber wenn ich das Übersetzungsverhältnis mit der Motordrehzahl auf 2000 U / min richtig einstelle und einen Lauf mache, ist es bei RPM 4000 U / Min nicht 100% korrekt. 

Ich denke, es liegt daran, dass ich ein 44-Zähne-Triggerrad habe. Aber ich denke, es wird enoth Impuls 

Ich fahre auf einem Bosch FLA 203 Dyno. 

Wenn ich einen Lauf mache, hat es Abweichungen von ca. 5-10kw.

Muss ich das MOI-Setup bei jeder Fahrt oder nur bei jedem Auto erstellen?

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Posted : 11/12/2021 7:36 pm
(@admin)
Member Admin

@furntrattrene,

The reason for the difference in RPM is most likely that the tires compress under load, so their effective diameter decreases. So the gear ratio changes. 

Make sure to always have high tire pressure during testing, and test with the brake on. You can drag the slider such that you get some good load while setting the gear ratio. 

 

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Posted : 11/12/2021 9:09 pm
(@furntrattrene)
Member

@admin 

Ich fahre mit einem Reifendruck mit ca 2bar. Also ist das zu wenig? Mit angezogener Handbremse ist nicht möglich bei einem Heckantriebenen Fahrzeug oder hab ich was falsch verstanden?

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Posted : 12/12/2021 6:58 am
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