How does castor trail relate to pneumatic trail ?
How does castor trail relate to pneumatic trail ?
(OP)
I'M TRYING TO UNDERSTAND HOW CASTOR TRAIL AND PUEMATIC TRAIL COMBINE/CHANGE WITH VEHICLE SPEED AND HOW THEY WILL EFFECT VEHICLE PULL IN COMBINATION WITH CAMBER AND CASTOR SIDE TO SIDE VARIATIONS.
RE: How does castor trail relate to pneumatic trail ?
Yes they'll all affect pull (depending partly on what you mean by pull- do you mean drift?). We quantify these effects by running a matrix of interactions, typically 81 runs for a given suspension.
BTW what's with the shouting?
Cheers
Greg Locock
RE: How does castor trail relate to pneumatic trail ?
We define pull/drift in 2 ways firstly the time to move a specific distance on a cambered road after we have released the steering wheel or secondly by the torque to keep the vehicle going straight on the same cambered road.
Currently I can improve vehicles by swapping tyres side to side and getting the tyre conicity's in the most helpful direction and tweaking the vehicles geometry helps a bit, but these are all a bit minor and everything is well within spec. Thus I'm trying to decide do I need to make a step change in geometry i.e more castor angle or is it really trail I'm after. I'm starting to look at the effects of toe settings,in over out. Or have I potentially got some suspension compliance going on giving me a steer effect.
RE: How does castor trail relate to pneumatic trail ?
Yes, the straightening effect will be partly governed by the total of mechanical trail+pneumatic trail.
Gillespie says look at scrub radius as well. camber is important
There are several other important factors which should be considered, but unless you work for my employer then I can't list them for you.
SAE paper 2000-05-0253 Identification of a vehicle pull mechanism may help
Cheers
Greg Locock
RE: How does castor trail relate to pneumatic trail ?
i've been told that the springs in the struts could be giving a force around the king pin axis when they are compressed is this likely ???
RE: How does castor trail relate to pneumatic trail ?
As to the other, you should draw a free body diagram for the wheel/hub.
Cheers
Greg Locock
RE: How does castor trail relate to pneumatic trail ?
Please see the collection of technical resources I listed in the thread shock friction (Thread800-57725). The mechanism for side-load on the damper (strut) is well explained. Resolving the forces and moments from a FBD will be elucidating as Greg suggested.
Best regards,
Matthew Ian Loew
"Luck is the residue of design."
Branch Rickey
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How does castor trail relate to pneumatic trail ?
Best regards,
Matthew Ian Loew
"Luck is the residue of design."
Branch Rickey
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: How does castor trail relate to pneumatic trail ?
Cheers
Greg Locock