horn operation on column how does it work ?

[phoenix]

Just building up upper column and I can't work out how the horn operates i.e. How the horn push earth etc.

[Heuer]

The centre horn push button presses down on the rod which, in turn, is in contact with Purple/black wire via the brass contact ring in the steering column. The overall column is grounded. Purple and black single bullet locates on copper spring/blade.

[phoenix]

But does the spring and brass contact under the brass like finfured collar not earth the rod ?

[Heuer]

Only when you press the horn button, until then the brass rod is insulated from ground by the white plastic sleeve and contact block.

[phoenix]

I have just checked on Barratts website I am missing the sleve and circip .