What is a Bogie, please explain

[Geoff Clifton]

My antenna man engineering skills think that camber and toe is a fixed adjustment relative to road side slope and straight tracking. I cant see the relationship with the Ackerman steering arms needing incremental difference between the inside and outside steer wheels. Is our research engineer watching? Anyone else want a go?

[T1 Terry]

Geoff, if it was that simple all vehicles would have the same toe in/camber adjust wouldn't they?

[Geoff Clifton]

Oh I didn't say toe and camber were simple and know only too well, having spent 4 figure money on R2 getting wedges put in and spring centres moved, that those measurements vary greatly for axle width, wheel size, average road camber and reverse camber where Jap trucks are imported with left hand drive suspension settings.

Just talking about the steering increment where the inside has to turn in more than the outside.

[Geoff Clifton]

A couple of excellent animations that show how steering geometry functions


https://www.youtube.com/watch?feature=p ... KlT6OpkjM4#!

http://www.bcot1.com/karting/

[T1 Terry]

Did it help your level of understanding of the Ackermann principle and steering geometry Geoff? There is so much science that goes into it, perfect Ackermann's gives very precise low speed steering control but becomes erratic at high speeds .... from here the knowledge level is vague because it's been a long while but.... if you move the point forward as in your first link better stability at speed is achieved, if you move the point behind the rear axle it becomes like self steer where any rut or camber of the road will steer the vehicle.... but I might have that back to front there is a lot more involved with caster/camber and toe in/out that will move the geometric point of intersection yet keep the max grip angle of tyre to surface while allowig for tyre deflection. A race car set up for high speed handling will near tear your arms from the sockets trying to low speed negotiate a park spot, a drag car set up to run straight and true all but needs to be dragged sideways to turn a shape corner, it's all a compromise.
Back to where this all started from, the issue with lengthening a chassis is the steer tyres will respond less to a direction change unless other alterations are made to the steering geometry, this is not always possible with some forms of front suspension as the required adjustments are not available.

T1 Terry

[RussellB[SA]]

My old Coaster (1974 chassis) had too much positive camber and the only way to fix that was to strip out some huge beam the axle stubs were connected to and heat treat the beam to adjust it.

That was too hard for me, and since it performed reasonable well I didn't bother.

Was this a common problem?

[norman]

It was a problem with imported buses into NZ. Beam axles had to be bent, and independent fronts had to have a wedge under the right hand side. Otherwise they were inclinded to duck into the left hand paddock. Japanese roads dont have a camber whereas we do...Thats according to hoyle and I may be wrong......

[Geoff Clifton]

Whilst I can't comment specifically on the Coaster it is a common problem. My GT17 needed a big $ mod and Ron's Rainbow got the bend. That was done cold and in place with a tool Ron likened to a railway track bender. $140 from memory.

The common reason given is that our roads have far more camber than most of the world which I find a bit odd. The more obvious that most vehicles are configured for left hand drive.

What irks me is that ADR's are pedantic in the extreme about seemingly trivial fastenings and measurements yet they allowed these vehicles to come in set up dangerously and sold unmodified. I concur with Norman about paddock diving. In R2 if I so much a looked at a fly on the windshield I changed direction which made for very tiring driving.

[T1 Terry]

The English busses all had to have their cross member beam bent and more than once when used on Aust roads, seems the pounding of rough roads bends them up in the middle. The wedges seem to be associated more with chassis lengthening or shortening, never quite got my head around the science, just left it to the experts. pro axle around these parts seem to be up on the game and Illawarra spring works for getting the thing sitting level first.
The new stabiliser bar on the rear of Brian's Hino made a huge difference to drivability, things that showed symptoms of shockie problems and steering geometry issues vanished after the bigger diam stabiliser bar was fitted. He is a very happy camper

[Jim]

Railway carriages run on bogies. Not always driven.