start switches...

[Jackpilot]

Gentlemen, start your bids....
http://cgi.ebay.com/ebaymotors/Boeing-737-B737-Engine-Start-Switches-Magnetic-Hold-28v_W0QQitemZ390036208792QQihZ026QQcategoryZ26439QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Note: just for info, I'm not the seller!

[Trevor Hale]

And he can keep them for what his reserve is at!

[Efe Cem Elci]

Overlooking the cost of making them ourselves, not looking bad right now at 60 a pop considering how rare they are to come by. At least thats how my brain is seeing it after a hectic day at the office...

[Trevor Hale]

Well I have put in a maximum bid, and it says my bid does not meet the reserve.. I know my bid was much larger then what it sits at right now. and they can stay there.
Trev

[Gsey]

I dont get why sellers still use the reserve not met method. Just start the auction at your lowest selling point and be done with it. Hopefully someone can still pick these up at a descent price, but from the sounds of things the reserve is quite high.

[Trevor Hale]

Something is fishy with the auction.. they have ended it early.

Don't know whats going on now!

[dnoize]

Its relisted without a reserve.

http://cgi.ebay.com/ebaymotors/Boeing-737-B737-Engine-Start-Switches-Magnetic-Hold-28v_W0QQitemZ390036352358QQcmdZViewItemQQptZMotors_Aviation_Parts_Gear?hash=item390036352358&_trksid=p3911.c0.m14&_trkparms=72%3A727%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318

wonder how much they will do.

Ive seen them go for anything between 100 $ and 1500 $ each on ebay.

New they are nearly 3000 $

Stef

[Jackpilot]

All these anonymous bidders!!ha ha..

[Michael Carter]

I think he might have finally gotten a clue that without an 1830 form he wasn't going to make a killing off of two $50 switches.

Feedback looks good as a seller, I don't think he knows what he has there and over-valued it a bit at first. Yeah, they're expensive switches, but without the 1830 they aren't worth squat to an FAA repair facility. The only thing they are worth is surplus or scrap. Except to us, of course.

I've never bought from him so caveat emptor applies here.

[dnoize]

a simmer doesnt need a 1830. So he will be getting whatever we are willing to pay. And when someone wants those and is willing to pay alot, these prices can go skyhigh.

As said in my previous message. I have seen these go for 100 $ each...but i have also seen them go for over 1000.

Last year someone listed a pair with a "buy it now" option of 1200 dollars. Nobody made a bid. The same seller reslists them a few weeks later with "no reserve". Over 30 bidders and they went for around 1500 $ a pair.

not the amount of money i would be willing to pay for them. I have been offered rediculous amounts for mine by simbuilders (but im not selling them).

Prices for parts labeled as 737 parts are going skyhigh the last few years. Firepanel for up to 1000 $ , aircon/packs panels for the same amount.

I have seen Honeywell locked toggle switches listed (and sold) for a price HIGHER than the price new from a dealer !

I've seen parts labeled as 737 parts that have NEVER been in a 737. A garantuee to drive the price up.

Seems we all are getting blind when we see 737 parts.

Fortunately i see prices go down again now. packs panels for less than 200 $, Still alot of money, but better than 1000$

A listing last month of 2 fireswitches, a squishy oxygen mask, mask container and a box full of switches and knobs went for 6 or 700 $. Someone got a good deal there.

But anyway. If demand is high, prices go up.

So i'm really curious for how much they will go.

And whats with all these anonymous auctions ?

Stef

[Efe Cem Elci]

past 300 now.

[RadarBob]

Out of my range I'm afraid - So I was looking at making my own.

Does anyone know how the real switch behaves when it is placed into the 'GRD'
position ? - Is there any spring resistance - Or is it just the resistance of the
switch mechanism ?

Rob

[dnoize]

Push in to turn to left or right.

Solenoid held to GRD.

There are some very nice designs to be found on this forum.


Stef



.

[RadarBob]

Thanks Stef - I hadn't realised it was necessary to push the control in before turning.

When you turn it, does it feel as if it's spring loaded ?

What I'm getting at is:

Could the switch be spring loaded such that it latches when at GRD, and the solenoid just releases the latch to allow it to spring back - Or does the solenoid need to push the switch back ?

Also, can the switch be put back to the OFF position manually once it has been put into GRD ?


Rob

[dnoize]

When you push them in, you feel a spring tension.

When the solenoid is not powered, its not possible to completely turn the switch into ground position.

Not sure if you can pull it out of the grond position manually. i can try that tonight.

stef



.

[tomenglish2000]

Ah, that explains the recess in the panel around the start switch knobs on the 767 engine start panel I have!

One of lifes little mysteries solved. Thanks!

Tom E.

[RadarBob]

Thanks Stef.

I don't think the 737 has the recess around the start knobs - But I have noticed that the knob shafts seem to stick out quite a way forward of the panel, and I did wonder why that was.

Rob

[Efe Cem Elci]

Yeah no recess on the 737s I've seen. Just the knob sticking out further than usual to allow for the push down and turn operation. Pops up when you get to OFF but rotates from CONT to FLT and back depressed.

[RadarBob]

Thanks for that Efe.

Do you know whether having pushed in the knob, it turns under spring pressure
towards GND - Or is it just the usual force required to operate the switch mechanism ?

Rob

[Efe Cem Elci]

I'll take a look tonight but the ones we have are custom made. Worst case, I'll ask the pilot :)

[ran56]

Thanks for that Efe.

Do you know whether having pushed in the knob, it turns under spring pressure
towards GND - Or is it just the usual force required to operate the switch mechanism ?

Rob

Force required.
You push and the turn left to GND, selonoid will hold it on GND,
till starter cut out and it will be released and return to OFF by
spring power.

Ran.

[Efe Cem Elci]

Ah, I might've misunderstood Rob's question. Ran is right, once depressed there is nothing forcing it towards GND. I thought he was asking about when the knob is depressed and moved towards GND, does it click into place by itself or is the full motion done manually.

[dnoize]

If you want i can take the cover of of one and make some pictures.

Stef

[Gallie]

Guys,

Bidding has ended, you can try to bid again.....

http://cgi.ebay.com/ebaymotors/Boeing-737-B737-Engine-Start-Switches-Magnetic-Hold-28v_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem390038395193QQitemZ390038395193QQptZMotorsQ5fAviationQ5fPartsQ5fGear

Mike

[dnoize]

Hmmm....whats going on with this auction ?

The auction wasnt supposed to have ended yet.

according to ebay:

The seller ended this listing early because the item is no longer available for sale.

and it has been relisted immedeately ?


Strange.....



Stef

[tomenglish2000]

I get the distinct feeling the seller is reading this thread.
Trevor points out that they are nearly worthless and the minimum bid is removed.
Others point out how the switches work and all the extra info is listed on the bid.

hmmm.

Tom.

[RadarBob]

Thanks all - Sorry if my question was not as clear as it could have been - But thanks for decyphering it ran56 !

I understand how these should work now.

I think the fact that the switch to GND is spring-loaded momentary when the solenoid hold-in is not enabled, makes the design easier.

Means that a replica switch mechanism could latch itself on mechanically, with latch release mechanism by solenoid - Don't need to use the solenoid to push/pull the switch back to OFF - So it can be smaller/less powerful.

The push-in first makes it a bit trickier though !

There is still the question as to whether the switch can be taken back to OFF manually once it has been placed into GND - Not too worried about that, but I think that could be handled by a release switch operated by pushing the knob a bit further in once it is in the GND position.

The new auction item says it was re-listed to include international shipping options.

Don't know if Tom is right, but the additional info is useful nevertheless.

Bit rough for top bidder though with another 6 days to go.

Don't know what top bid was, but I suppose it was greater than $400.

From these discussions though, it is clear that the device is not so easy to reproduce, so it is worth a fair bit to someone who wants to add that bit of extra realism to the start up routine.

If you wouldn't mind posting a picture or two Stef, that would be great - Assuming it is possible to take the cover off without too much hassle !


Cheers,

Rob

[tomenglish2000]

I would also be interested to hear how you can place the switch back to OFF from GND. I know that it is possible.

Tom.

[Michael Carter]

If it's similar to the solenoid-held switches that Sperry used in the SP-50, just turn it back to OFF.

The mode control switch on the AP works this way and it must be pushed in to turn when power is applied. It cannot be manipulated without power applied as the solenoid mechanical latches are in the way of the switch rotation mechanism.

It can be manipulated by hand to the MAN position with power applied. I don't see why it wouldn't be the same with the start switch.

Suppose the switch didn't release and you didn't get starter cut-out? I would think rotating the switch by hand might be one of the first memory items on the checklist. Anyone have a checklist that has this?

[ran56]

From B767 QRH

Aborted engine start

Condition: During a ground start, an aborted engine stat condition occurs.

Fuel Control switch - cutoff
If the engine start selector is in GND:
Motor the engine for 30 seconds.
Engine start selector - Auto

[Jackpilot]

Maybe this can be an idea to work from.
http://www.thesolenoidcompany.com/rotary_d.php

[ran56]

found this link couple of days ago.
Not sure if I saw it here in one of the posts

http://www.hanskrohn.com/BuildingTips/EngStartSwitch/EngineStartSwitch.htm

[Jackpilot]

Stef

I just realized, looking back at old posts, that you were supposed to surprize us with a new gizmo in that vein??? no,,?

Cheers
JP

[dnoize]

Stef

I just realized, looking back at old posts, that you were supposed to surprize us with a new gizmo in that vein??? no,,?

Cheers
JP

hmmmm trying to figure out what i promised and forgot about.........

[dnoize]

the switch can be turned back from GRD to off manually when the solenoid is still powered. Requires quite a bit force. How much depends on the power you apply. At 28 volts it needs quite some force. but the solenoid is still holding at 12 v and then it doesnt need much force.

attatched some pictures. basically its a kind of cam that pushes a combination of micro switches.
When the solenoid is powered it pushes a shape in a V-shaped gap in the cam, thus locking it.

Just let me know if you need more info.

Stef

[RadarBob]

Thanks Stef - Nice Pics !

I was thinking along those lines - But I had it with a thinner shaft and a number of wheels with notches in - Knew there had to be micro-switches in it though !

I guess there is probably a spring in the front or end sections ?

Can you see how the detents are done ? Does it rely on the micro-switches falling into the notches in the shaft - Or does something else do that ?



Cheers,

Rob

[Efe Cem Elci]

I'll also try to get some pics of the custom job I have in hand. Just to give an idea.


Thanks Stef - Nice Pics !

I was thinking along those lines - But I had it with a thinner shaft and a number of wheels with notches in - Knew there had to be micro-switches in it though !

I guess there is probably a spring in the front or end sections ?

Can you see how the detents are done ? Does it rely on the micro-switches falling into the notches in the shaft - Or does something else do that ?



Cheers,

Rob

[Jackpilot]

hmmmm trying to figure out what i promised and forgot about.........

Public apology...was'nt you....

[dnoize]

no problem :-)

[vidarf]

Can I bother you with more detailed images from more angles, dnoize? :)

[dnoize]

sure, if i find time to open them again.....what angle ?


Stef

[dnoize]

Can you see how the detents are done ? Does it rely on the micro-switches falling into the notches in the shaft - Or does something else do that ?



Cheers,

Rob

Theres a disk in the front end with a spring and little metal balls that takes care of the detents.

I'll try to capture them with a photo if i find the time.

Stef

[RadarBob]

Thanks for the info Stef.

Been doing a few rough sketches to see if I can come up with something simple to do the job. I'm ok on electronics, but I don't really have the tools to do any complicated mechanics.

I think I have a solution for the solenoid hold-in and flick-back, but it depends if I can get enough return spring power to overcome the detent and any friction due to the spring on the knob push-in, within the available space and with only 30 degrees of rotation.

Not sure what size those original switches are, but it appears from the Engine Start Panel I have in progress here, that they would need to be something in the order of 50mm wide by 50mm high - Length behind the panel not so critical, but around 125mm I would think.

I was musing over using opto-sensors instead of micro-switches to get the resistance and size down.

Haven't figured out how to get the trigger to release the solenoid at the correct N2 (56% ?), but I assume this can be done using SIOC.

Cheers,

Rob

[Gsey]

56% is correct.

Gary

[vidarf]

Angles: both sides, top (above the shaft, on the round edge).

Another thing - how does the switch operate? Am I correct here:

- OFF to GND: push in, rotate left
- OFF to CONT, FLT and beyond: rotate right, no push in

I've thought about making my own switches - if my assumption is correct, it should be relatively easy to do so.

[ran56]

In the starters of B742 (real panel I have here)
You have to push to rotate to both sides.

[Efe Cem Elci]

Angles: both sides, top (above the shaft, on the round edge).

Another thing - how does the switch operate? Am I correct here:

- OFF to GND: push in, rotate left
- OFF to CONT, FLT and beyond: rotate right, no push in

I've thought about making my own switches - if my assumption is correct, it should be relatively easy to do so.

Push in both ways.

At OFF:
Push in, rotate left to GND.
Push in, rotate right to CONT, FLT, ...

At GND:
rotate right to OFF, pops out.

At CONT:
rotate left to OFF, pops out.
rotate right to FLT.

etc.

You get the idea...

[dnoize]

nothing to add to what Efe said.

Except for the extra pictures, but i didnt find time yet to make more.

Stef