switch/ solenoid What's bad?

[Soundguy]

The bypass type used to be common.

You have the 2 large lugs for battery, and starter. then you have 2 small lugs.

One lug is for switched power to the coil.. The other end of the coil is tied to the mounting leg on the solenoid. The other small post will become 'hot' when the solenoid is energized. The reason it is called a 'bypass' type is because 'way back when'.. lots of tractors and vehicles used an ignition resistor in line with the coil. For instance.. the car may have a 6v coil, dropping resistor, and a 12v electrical system. During starting.. power at the battery coupld drop low.. like 8-10v.. once you ad din the drop from the ignition resistor.. there was not always sufficient power to the coil for reliable starts. You hook the line from the bypass terminal to the coil.. thus when you energize the solenoid, you pass battery power directly to the coil for a short period of time while the starter is turning over and system votlage is low. This momentarilly puts 8-10v on the 6v coil for extra hot sparks for a second or so.. ( doesn't hurt anything).

If you look at this as a relay, then, the bypass unit is a DPST .

( double pole, single throw )..

( one pole is the high current portion.. the other pole is the low current feeding the bypass terminal )

An isolated solenoid is a SPST switch.

The reason it is called 'isolated', is because the coil contacts are isolated from the mounting base.

If you want to add more junk tot he fire, electrically speaking.. the contacts on the dpst, and the spst are "NO" ... ( normally open ). If the relays were double throw, instead of single throw, then they may have a common post, and a set of 'NO', and a set of 'NC' contacts.. ( nc=normally closed )

Soundguy

 

[PineRidge]

The bypass type used to be common.

You have the 2 large lugs for battery, and starter. then you have 2 small lugs.

One lug is for switched power to the coil.. The other end of the coil is tied to the mounting leg on the solenoid. The other small post will become 'hot' when the solenoid is energized. The reason it is called a 'bypass' type is because 'way back when'.. lots of tractors and vehicles used an ignition resistor in line with the coil. For instance.. the car may have a 6v coil, dropping resistor, and a 12v electrical system. During starting.. power at the battery coupld drop low.. like 8-10v.. once you ad din the drop from the ignition resistor.. there was not always sufficient power to the coil for reliable starts. You hook the line from the bypass terminal to the coil.. thus when you energize the solenoid, you pass battery power directly to the coil for a short period of time while the starter is turning over and system votlage is low. This momentarilly puts 8-10v on the 6v coil for extra hot sparks for a second or so.. ( doesn't hurt anything).

If you look at this as a relay, then, the bypass unit is a DPST .

( double pole, single throw )..

( one pole is the high current portion.. the other pole is the low current feeding the bypass terminal )

An isolated solenoid is a SPST switch.

The reason it is called 'isolated', is because the coil contacts are isolated from the mounting base.

If you want to add more junk tot he fire, electrically speaking.. the contacts on the dpst, and the spst are "NO" ... ( normally open ). If the relays were double throw, instead of single throw, then they may have a common post, and a set of 'NO', and a set of 'NC' contacts.. ( nc=normally closed )

Soundguy

Soundguy you're not going to tell me that the above only applies on a Mon., Wed., & Sat are you?

 

[Soundguy]

Uh.. no.. why? ( I'm missing a joke somewhere aren't I? .. I can just feel it... (grin )

Soundguy

 

[Iplayfarmer]

Ok.. you have the iso type. Why not just get a 2-3" piece of wire with eyelets, and attach one ont he small terminal, and the other on the mounting bolt.. Should be set then.

Soundguy

The 2"-3" piece of wire is easy. I have some eyelets, but time and ambition tomorrow are going to be the true deciding factors whether I put on the eyelets or just "smush" the bare wire in between the nuts.

 

[Soundguy]

I prefer eyelets.. however had had to do some 'smushing' before to get going.

If you do use the 'smush' method.. Add a washer between the nut and the wire.. that way the nut turning against the wire when you tighten ( or remove ) won't drag and break the wire... but rather just run against the washer and really evenly 'smush' the wire!

Soundguy

 

[Iplayfarmer]

I prefer eyelets.. however had had to do some 'smushing' before to get going.

If you do use the 'smush' method.. Add a washer between the nut and the wire.. that way the nut turning against the wire when you tighten ( or remove ) won't drag and break the wire... but rather just run against the washer and really evenly 'smush' the wire!

Soundguy

Thanks for the advice. I was thinking I'd put an eyelet on the end of the wire that goes over the small post since I have that size of eyelet. I'll probably just put the other bare end of the wire around the mounting stud between the solenoid mount and the firewall. This would avoid the "drag and break" scenario.

On a new tractor with good paint that might not work, but I'm sure I can find some bare metal on this old beater.

One more question...What size of wire should I use here? I'm pretty sure that I have short pieces of everything from 20 guage up through 8 guage.

 

[Soundguy]

This is only to power the coil. match the wire size to whatever is hooked tot he other side of the coil.. I wouldn't go smaller.. though larger is ok.. but not needed.

My 'guess' is 12awg stranded.. though certaintly could be different.

A bit of emory paper will make that a nice clean metal contact area.

Soundguy

 

[RobJ]

Another thought, go out and find the single small post type. They still make them. Make sure when you bolt the new one to the frame, fender, whatever, it has a good ground. Otherwise it won't work.

Rob

 

[Soundguy]

Why? He's already got a (probably non-returnable) 4 poster that will work fine... Why waste more gas and run around town to buy a different solenoid that will do the same thing minus 2" of wire..??

Soundguy

 

[midlf]

Wire size, #20 should be just fine. Coils don't take a lot of power and you do not energize them long enough to heat up the wire. Best choice of wire for this application is based on mechanical needs. If this is a high vibration application I would go with a heavier gauge. Potential exposure to mechanical damage would also suggest a heavier gauge.