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Master and Starter Solenoids

TerryWighs

Well Known Member
I have noticed a couple different orientations on these devices. Is there a preferred veritcal orientation (which way is "up") on each of these. Thanks
 
I really don't think it matters with the Starter solenoid.

On the master:
The master you ground to cause it to close. That said, the battery cable must be on one particular side of the solenoid. I don't think this will matter on the starter solenoid. On it, you must provide the voltage to close the contactor.
 
Starter Soleniod and ACRO

There were some people who had the starter engage while doing positive G. So they mount them sideways.
 
I understand the "hook up" electrical concept. The question was directed to the physical arrangement regarding mounting. I had heard comments of because of the way the solenoid moves (master), that it had to be orientated in a particular matter for the contacts to function optimally?
 
There were some people who had the starter engage while doing positive G. So they mount them sideways.

I could see that. I dissected one that I thought had failed. The spring was not that stout. I would think contactor portion on bottom would address that issue. The contactor portion is the part where the leads connect.
 
EAA taught me that.

There were some people who had the starter engage while doing positive G. So they mount them sideways.

Took one of those two day electrical coarses a couple of years ago near Boston in a SportAir EAA workshop and that's exactly how they taught us to mount the starter solenoid. If your going to do a lot of high G stuff it sounded like a good idea. Even if the solenoid engaged for a second it would be bad.
 
Don't Van's instructions/schematics have it mounted "upside down" for that reason? That's how I did mine...

See DWG 31A.
 
The old theory was that you wanted gravity to help pull the master closed and the starter open in the event of a dead spring. So.... Starter contacts down and master contacts up. That's their story and I'm sticking to it.
 
This is a quote from Aircraft Spruce about their master relays:
"Mounting Position: Recommended mounting with cap down". I have always supposed that is because they want gravity to help the contacts.
I have noticed a couple different orientations on these devices. Is there a preferred veritcal orientation (which way is "up") on each of these. Thanks
 
This is a quote from Aircraft Spruce about their master relays:
"Mounting Position: Recommended mounting with cap down". I have always supposed that is because they want gravity to help the contacts.

Just make sure you don't confuse the "cap" with the "top". The ACS relay appears to have the cap on the *bottom* of the relay (for whatever reason...maybe to keep moisture out?).

In this case, mounting with the "cap" down results in the relay being mounted rightside-up, so to speak (I believe).
 
Yeah, most are a "can" with the insides, then a "cap or lid" is attached. Putting the smooth bottom of the can up is correct. (Not sure if that made any more sense than what was previously said)
 
Battery Solenoid Current Flow

Is there a preferred flow direction through the battery solenoid aka battery contactor aka master solenoid? (for search purposes) As I am getting ready to crimp the #2 cables back there on my RV-8, I noticed 'BATT' etched on the solenoid which I am assuming is the terminal that goes to the (+) on the battery. But when I do that it looks backwards from the wire bundle routing recommended in the plans.
venm37.jpg
 
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