K&c test lateral loading trail value

[alok_singh]

Hi all,
Is 30 mm trail is standard for applying lateral load or do I have to check what is actual mechnical trail at design condition(unladden)?

Thanks
Alok

 

[GregLocock]

Pneumatic trail is what you are after, from your tire model divide the self aligning torque by lateral force at the operating condition. This gives you the pneumatic trail.

The mechanical trail is fixed by your geometry and is automatically present when you do a K&C test.

In the absence of tire data, or if you wish to standardise, 30mm for pneumatic trail is fine. Run 0mm as well.


Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[alok_singh]

I am running with 0 mm trail also but in literature it's given lateral load is applied at pneumatic trail + mechnical trail. In some reports(for different class of vehicle) I am seeing 17 mm castar trail and in some 29 mm cater trail. And they have taken 30mm as trail.

 

[GregLocock]

Yes, because your suspension always give you the mechanical trail.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[alok_singh]

Hi Greg,
Thanks for the clarification, I have few query, If possible please clarify them.

1.In steering compliance with, In-phase loading and out-phase loading how steering system compliance effect. And do I need to introduce compliance of tie rod while doing this?

2.Is track change is importance for dependent suspension(beam axle 3 link).

3.Does force roll center height changes much in dependent suspension?(as per my understanding kinematic roll center(KRC) lateral movement effect the height of force roll center and in beam axle with panhard rod and KRC doesn't change much laterally).

Thanks
Alok

 

[GregLocock]

1 You are basically measuring the rack/subframe contribution in the in phase test
2 beam axle? no
3 Not much, so long as the pnhard is relatively horizontal. Laterall location of the RC is something that some people think is important. Milliken, Milliken and me don't.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?

 

[alok_singh]

Just a follow up question in case of rcb steering system we need to lateral compliance in phase or out phase?
Thanks
Alok

 

[GregLocock]

You always need both, although if pushed for rig time in phase is more important. Opposing is diagnostic for steering arm stiffness etc, but not directly as useful as parallel

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

http://eng-tips.com/market.cfm?