Throttle body return springs

[Belo]

I'm having a hard time figuring out what that means :

The throttle actuation system must
use at least two (2) return springs, so that the failure of any component of
the throttle system will not prevent the throttle returning to the closed
position.

First: can I put two springs side by side that make the throttle return in closed position??? Or does it mean that I need two spring system that would bring back my throttle in closed position?

Second: "will not prevent the throttle returning to the closed
position.
" I tought we wanted the throttle to close if a failure occurs!! seems safer to me !

If somebody could help me out I'd really appreciate it!

Thanks
Alex

[Belo]

I'm having a hard time figuring out what that means :

The throttle actuation system must
use at least two (2) return springs, so that the failure of any component of
the throttle system will not prevent the throttle returning to the closed
position.

First: can I put two springs side by side that make the throttle return in closed position??? Or does it mean that I need two spring system that would bring back my throttle in closed position?

Second: "will not prevent the throttle returning to the closed
position.
" I tought we wanted the throttle to close if a failure occurs!! seems safer to me !

If somebody could help me out I'd really appreciate it!

Thanks
Alex

[Dave M]

"3.5.4.2 Throttle Actuation
The throttle must be actuated mechanically, i.e. via a cable or a rod
system. The use of electronic throttle control (ETC) or "drive-by-wire"�
is not permitted.
The throttle cable or rod must have smooth operation, and must not have
the possibility of binding or sticking. The throttle actuation system must
use at least two (2) return springs, so that the failure of any component of
the throttle system will not prevent the throttle returning to the closed
position.
Note: Throttle Position Sensors (TPS) are NOT acceptable as return
springs. Also, a spring at the pedal can only be counted as one of the
springs if the throttle cable is a "push-pull"� cable and not just a "pull"�
cable."

The throttle should always spring back to closed (little or no airflow). I think the wording may be a litle weird. We use a stock throttle body which has the tps built in, and simply add a second torsion type spring with the stock one. We added a third at the pedal to be safe.

[CMURacing - Prometheus]

"the failure of any component of the throttle system will not prevent the throttle returning to the closed position"...i.e., your positive pedal-stop breaks, the throttle goes way past wide open, which causes your linkage to fail in tension. with an inadequate return spring (or none at all on the throttle end), the throttle would remain open. this would be a failure which prevents the throttle returning to the closed position.

[Z]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Belo:
... will not prevent ...
</div></BLOCKQUOTE>
The above phrase is a "double negative".

Since "prevent" = "not allow" the rule is saying "any failure WILL NOT, NOT ALLOW the throttle to close". Since the negatives are supposed to cancel, this means "any failure WILL ALLOW the throttle to close". (Actually it means less than this, but that's another story...)

The use of double negatives, except maybe in jokes (or politics!), is regarded as bad practice. It is especially bad practice in technical or legislative type documents, and even worse when that document is dealing with safety issues. The writer of that rule needs a kick up the bum!

FWIW, any rules, technical instructions, orders, etc., are easiest understood if written or spoken in a positive manner. Eg. "The throttle actuation system must use at least two (2) return springs, configured so that if any component of the system fails, the throttle will return to the closed position". Or something like that... http://fsae.com/groupee_common/emoticons/icon_smile.gif

Inglish iz haad, faw mee tu! Praktis, praktis... http://fsae.com/groupee_common/emoticons/icon_confused.gif

Z

[Belo]

Hahaha thanks a lot it s clearer now!

I found of way of doing it nicely!

[CMURacing - Prometheus]

oh you want to argue english now eh? http://fsae.com/groupee_common/emoticons/icon_smile.gif...

"prevent" is not really a negative, so "not prevent" is not technically a double negative. i would have used a similar phrase, because its really a catch-all for throttle problems.

EXAMPLE: in 2004, our plenum/throttle body was outside the roll envelope (because we were in a rush to pass tech and didn't set our ride height way down ;-)). the inspectors argued that, in the event of a rollover, the plenum/throttle body could be torn free of the car, sending the engine right to WOT, which could cause all sorts of problems (it being upside down, etc). this, for example (the plenum being ripped free) would be a failure of a component that prevented the throttle from returning to the closed position.

So, instead of "will allow", the wording should be more like "will/must maintain the ability of the throttle to accomplish its intended task" or "shall maintain the capability of returning to..."

-Major English (the only student on our team with any sort of humanities concentration as well as an engineering major) http://fsae.com/groupee_common/emoticons/icon_biggrin.gif http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Z]

Mike,

English teacher (with pompous accent) - "The negative most often means 'No', except, of course, when spoken by women, when its meaning is somewhat variable. The meaning of the double-negative is more difficult to pin down, and remains the subject of much spirited debate. But, fortunately, we can rest assured that the meaning of a 'double-affirmative' is always as expected, namely the positive affirmation!"

Voice from back of class - "Yeah, right." http://fsae.com/groupee_common/emoticons/icon_smile.gif

Z