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Peteohms
10-11-2013, 06:22 PM
My Starter solenoid started giving out on me. The attached picture is what my starter solenoid looked like and also what my new one looks like. The new one is an S 5049P.

Peteohms
10-11-2013, 06:30 PM
On the S5049P the terminals are Battery (lower large term.), Switch (lower small term.) and Starter (upper large term.)

What I'm concerned with is that my old solenoid had the starter and battery wires swapped. Can they be switched like that?

jtpitkin06
10-13-2013, 06:51 AM
Not a problem on that type contactor.



There are two common types of contactors used on aircraft, a 3 terminal and a 4 terminal.


On a three terminal solenoid contactor the switch connection powers the solenoid closed by grounding through a master switch or starter switch. There is an internal connection on the battery side to the windings of the coil so positive voltage is always present at the small switch terminal. If the battery is connected to the wrong side of the large terminals, the solenoid will not close by grounding the small terminal.



A four terminal contactor like the one pictured typically has no internal connection to the solenoid windings. One of the small terminals must be connected to a power source. The control circuit may be either positive to close or grounding to close. Four terminal contactors have no restriction on which of the large terminals connects to the battery or the starter. So hook it up either way and it will work just fine.

The above types are the most common, there are many variations on the basic types dealing with internal connections. It’s pretty simple to test them with a battery to figure out what’s going on inside.



One additional note: Be aware that starter solenoids should be mounted upside down, terminals down. If mounted terminals up, a hard bump on landing can cause the solenoid slug to slap closed and engage the starter. Battery contactors are mounted terminals up to remain connected if you bump them on landings.


John

Peteohms
10-13-2013, 07:45 AM
Thanks John. I thought I was ok. But, even though the replacement solenoid looks the same as the old solenoid, I couldn't find anything that says why one terminal is marked starter and the other battery in the instructions. It is firewall mounted.

SkyPirate
10-13-2013, 06:14 PM
It is the same as a UTV winch selinoid, i used one on a wireless remote control 12 volt tree stand that will lift a guy in a wheel chair up 16'

HansLab
10-16-2013, 10:34 AM
What do you mean by 'upside down'? The pic shows a kind of solenoid I have, but mine is mounted to the FW (vertical...)

Danzer1
10-17-2013, 04:51 PM
He means with the terminals facing down. Many don't do it, but it is the best (safest) approach. Perhaps you could find or fabricate an 'L' bracket to mount it with the terminals facing down.

Greg

jrevens
10-19-2013, 12:39 PM
This has been discussed in great detail on this forum... check out:

http://www.teamkitfox.com/Forums/showthread.php?t=3671&highlight=solenoid

The right side up/upside down issue pertains specifically to Series 70 White-Rogers solenoids, which are very commonly used in aircraft. It may be a consideration in other brands/types also, but not necessarily yours. There are solenoids that are designed for horizontal mounting.