Understanding ACC Schematic - PeachParts Mercedes-Benz Forum

cook · #1 02-08-2013, 10:06 PM

I am trying to understand how the switch works in the circuit of the ACC-III schematic.
The attached picture is of switch B. I have added the numbers to help indicate the contact points in the switch. I apologize for the crude drawings.

Here are my questions.

1. Is this switch off or on? (I think it is off, or out. ie. not pushed in)

2. What does the circuit look like when it is in the other position? (For example, does the connection from 1 to 2 become 1 to 3 and 4 to 5 becomes 5 - 6?)

3. Other switches in other parts of the schematic just have 1 to 2 and 4 to 5. There is no 3 or 6. When this part of a switch moves, do 1 and 2 stay straight and the circuit is broken?

Has anyone figured this out?

Silber Adler · #2 02-08-2013, 11:29 PM

The only way that makes sense to me is for point 1 and 5 to be fulcrums. Otherwise point 3 and point 6 would be redundant.

jay_bob · #3 02-10-2013, 12:12 PM

With switch in its resting position 1 - 2 and 4 - 5 have continuity.
With switch in its operated position 1 - 3 and 5 - 6 have continuity.

I've worked for European based control companies for 25 years, if y'all ever get stumped on the Euro diagrams let me know...

cook · #4 02-10-2013, 09:13 PM

Great, thanks so much.

jay_bob · #5 02-10-2013, 10:08 PM

I don't think the link or pic made it...

cook · #6 02-11-2013, 11:23 AM

Will get the link posted late today. Sorry.

cook · #7 02-11-2013, 06:46 PM

The link below is for switch "E" from the ACC - III schematic.

Loking at the top 2 lines of the switch, it shows they have continuity.

What happens when the switch is moved to its operational position?
* Does the top line lose continuity, but the 2nd one has continuity?

Now, for the bottom 2 lines, lets call these 5 and 6. At rest, 5 and 6 have continuity.
* When operational, does 5 lose continuity, but 6 has continuity?

jay_bob · #8 02-11-2013, 08:33 PM

Normally the convention for the diagrams is that the switch shows its continuity in the "not operated" position. I would say that the not operated position for this button is when the button is not pushed in. I believe "e" is the "off" button so it would make sense that when the "off" button is not pushed you would be operating and so have the most contacts made up.

from the top, closest to the actuator symbol:
row 0, right under symbol, looks like a wire passing through
row 1 is normally closed (i.e. made when button is not pushed) American symbol --| / |-- otherwise known as Form B.
row 2 is normally closed
row 3 and 4 is a change-over contact, when not pushed, it goes straight through from left to right. When pushed, the "bar" tips down, leaves the contact it was touching, and touches the free contact in the row below and to the right. The 'pivot' is at the left. We call this a Form C in the US.

Row 5 and 6 are just passing through

-break-

row 7 and 8, change over contact, straight through when not pushed, lower left and upper right connected when pushed. Note the lead from lower left crosses but does not appear to connect to any of the lower rows since I cannot see any dots.

Row 9, passing through.
Row 10, and row 11, normally closed.

It appears that the right side of row 11 connects to row 12. I just barely make out a dot joining the line coming down off the right of row 11 where it passes over row 12. But that could be an artifact of the image.

Another side story - artifacts are always a risk, when dealing with old prints. I once had to deal with a power plant that had drawings so old they were ink on linen. Unfortunately they had mildew on them and some of the spots were just in the right place to look like a connection dot. Luckily we were able to very carefully wash the drawings - the India ink was permanent so it did not wash out -and get the mildew spots out.

I am totally spoiled with AutoCAD, no move, copy, erase, or undo possible with ink on linen.

jay_bob · #9 02-11-2013, 08:36 PM

Do you have the entire schematic for the controller? I would be interested to see what is inside it. The US ETM does not show any of the innards, only the external connections.