Cockpit Master Switch

[SNasello]

Im wondering where teams have purchased their cockpit pull on, push off type switchs from. We have one from polaris off their snowmobiles and have realized it works opposite. This is a bit of an urgent issue since i cant find anywhere that sells the proper switch (and isnt 2.5 inchs long). Otherwise is there a way of reversing the way the switch i have works?

[SNasello]

Im wondering where teams have purchased their cockpit pull on, push off type switchs from. We have one from polaris off their snowmobiles and have realized it works opposite. This is a bit of an urgent issue since i cant find anywhere that sells the proper switch (and isnt 2.5 inchs long). Otherwise is there a way of reversing the way the switch i have works?

[Kurt Bilinski]

How about changing how the switch connection is used. That is, if you use it to open your ignition circuit now, how about using your reversed switch to short your ignition system to ground.

[Sooner_Electrical]

You can flip the logic of the switch thru a relay.

www.autoshop101.com/forms/hweb2.pdf (http://www.autoshop101.com/forms/hweb2.pdf)

makes in simple to understand.

[Kurt Bilinski]

True, but it's another part, adds weight, adds wires and cost. Far better is changing howhow the switch used (if possible) instead of adding more parts. If I were a judge, I'd give points for the creative fix instead of complicating it.

[Mike Flitcraft]

Making it work, vs. not being able to pass tech, are two different things.

In a pinch, go for the relay.

[Pete M]

Shorting stuff to ground to disable a circuit is always dodgy. Sure, it may work, but i don't want to have to replace the fuse every time someone hits it accidentally. I'd either find a switch that has the polarity expected, or use a relay to flip the polarity if i were desperate. Relays aren't exactly heavy.

Engineering isn't about being creative for the sake of being creative. That's called art. Engineering is about finding the best solution for the problem. If that's firmly "inside the box" then so be it.

[JR]

Following up on the original question... anyone willing to volunteer where they have found an appropriate switch to buy...??? I have seen a couple in the Digikey catalogue but wondered what else is out there.

[BStoney]

http://www.onlinecomponents.com/product/2172580
IDEC P/N: HA1E-V2S1R

Only 1" in diameter, NC contacts

http://img519.imageshack.us/img519/8665/img0742mc3.jpg

[Geoff Chadwick]

The switch we are using is a small push-pull switch that has a pair of screw terminals on the back. You can run wires into it or use small ring lugs if you desire. Otherwise it functions as the rules specify (push break, pull make) and a version can be had from an Advance Auto Parts location near you.

Advance Auto Parts PN 85933
$3.99 US in retail stores

I know similar versions can also be found at Radio Shack or other hobby stores.

[James Waltman]

Stefan,
You must have something mixed up if the switch is working backwards.
I can't really help with that one.


For all of you guys running lame headlight switches (https://www.dormanproducts.com/cgi-bin/vm91corp30r/item-dtl.w?sid=0x00c42917&item=85933&icrid=&clt=hwrap1&vsrch_str=85933&vsrch_brand=ALL&vsrch_cat=ALL&st_amount=&end_amount=&start=&vfrom=&prev=&vnext=&category_list=:0) or switches meant for machine tools...

When this came up last fall:
http://fsae.com/eve/forums/a/tpc/f/125607348/m/84710158631/p/1

The rules for Mini-Baja (http://www.sae.org/students/mbrules.pdf) actually list part numbers:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
32.7.1 Kill Switch – Type
The kill switch must be one of the following:
(A) 01-171 Ski-Doo kill switch available at
http://www.mfgsupply.com/m/c/01-171.html?id=UxSI4Vzn
(B) After market WPS#27-0152 or 27-0124
http://www.parkeryamaha.com/index.asp?PageAction=PRODSE...earch=27-0152&Page=1 (http://www.parkeryamaha.com/index.asp?PageAction=PRODSEARCH&txtSearch=27-0152&Page=1)
(C) A Stock Polaris # 4110106
</div></BLOCKQUOTE>

http://www.mfgsupply.com/img/snowmobile/elect/01-171.jpg

[Brian S]

The Ski-Doo switch from MFG Supply does work backwards, at least from how I expected it to work. It is open in the out position and closed in the in position. I can think of two simple ways to deal with this.

What we did was have the switch trip a digital input on the ECU telling it to kill the engine. Pushing the switch, closing the circuit, connects the input to 5v, killing the engine.

The other way would be using a NC relay supplying power to the ECU. When the switch open the relay would be closed allowing the ECU to run. Closing the switch would open the relay, cutting power from the ECU.

[Chris Boyden]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">What we did was have the switch trip a digital input on the ECU telling it to kill the engine. Pushing the switch, closing the circuit, connects the input to 5v, killing the engine. </div></BLOCKQUOTE>

Isn't that not allowed per the rules?

87a is the NC terminal on automotive relays

[Bill Kunst]

The switch, per rules, should be direct acting on the battery supply to all components. It should kill the brake light, to give you an idea of how complete the killing of power should be.

[Kyle Walther]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bill Kunst:
The switch, per rules, should be direct acting on the battery supply to all components. It should kill the brake light, to give you an idea of how complete the killing of power should be. </div></BLOCKQUOTE>

3.4.9.2 Cockpit-mounted Master Switch
The location of the cockpit-mounted master switch must provide for easy
actuation by the driver in an emergency or panic situation. The switch
must be located within easy reach of the belted-in driver, alongside the
steering wheel, and unobstructed by the steering wheel or any other part
of the car. It is suggested that it be placed on the same side of the
steering wheel as the shifter mechanism.
The cockpit-mounted master switch must be a push/pull Emergency
switch. The switch must be installed such that: (a) from the ON position,
pushing on the switch will disable power to the ignition and all fuel
pumps, and (b) from the OFF position, pulling on the switch will enable
power to the ignition and fuel pump(s).
The switch may act through a relay. Examples of typical switches that
meet these requirements are shown in Figure E.

it doesn't say anything about killing all components, just the ecu and fuel pump

[JHarshbarger]

The main, rotary switch needs to kill everything, but the cockpit power switch is only responsible for killing the engine. I thought it had to kill everything, too, but I checked the rules. In fact, I believe the brake light is supposed to be able to work when the cockpit switch is off.

On second thought, they might have a problem with the switch "signaling" the ECU to turn the engine off. It says it needs to disable power, not signal another device to disable power. Might not be an issue though.

[Biggy72]

Brian emailed the rules committee about his setup and they said it would be fine.

[Brian S]

Dear Brian,

It is perfectly acceptable to have the cockpit mounted master switch cut the ignition and fuel by acting on or through the ECU.

Rules Committee,
FSAE

[Bill Kunst]

When I was working on the UW-P team, we had to rewire the car so that the main switch, cockpit, and brake overtravel all killed every component. This occured when we went through the tech inspection and the brake light stayed usable when the cocpit and brake overtravel were tripped. Maybe we had inspectors that were not well versed with the rules.

But, in now way should you use a relay to kill the power.

[Poe]

Bill, we had the same experience in tech inspection in '04.

[Pete M]

That's really weird. I mean, the rules are pretty clear that the only things the dash switch and over-travel switch have to kill are the fuel pump and ignition. The cockpit one specifically says it can operate through a relay, while the brake one just says it can't involve anything programmable. It doesn't say it, but i'd assume a relay counts as an "analog component".

Both these switches are wired in series on our car and function to kill the ignition relay (which our fuel pump is also on). We've never had any problems with tech.