ZachGrant

Building a Sentry Module

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Well I talked to Mike Links today and we are both thinking my Sentry is no good. I am going to send mine to him to test but the price tag on a new one ($2300) has got me thinking about trying to build one. After all this was 1970s technology. I should be able to figure out something? The bottom is just something I sketched up tonight and is a very rough draft. I would use a 12v time delay relay with a .1 second on delay. I'm not certain how the factory pressure switches function, but I would need a switch that closes at 0psi.

Time delay relay: https://www.amazon.com/GEREE-Module-External-Trigger-Automotive/dp/B01DDCLA3M/ref=pd_lpo_vtph_60_lp_t_3?_encoding=UTF8&psc=1&refRID=4NF3JJ0Q8P95MCD594S5

Might be better off to go with a solid state? https://www.amazon.com/Timer-Delay-Relay-Hours-Cycling/dp/B00PD65UGA/ref=sr_1_1_sspa?s=hi&ie=UTF8&qid=1507686534&sr=1-1-spons&keywords=12vdc+time+delay+relay&psc=1

 

Do you guys see any problems with my thoughts here? I'm thinking this should provide the same protections as the original sentry. The side opposite of what you are shifting to has to read 0 psi before the side commanded can engage. The time delay should also prevent both sides from being engaged at the same time. This setup will not have a clutch reset or a sentry light as the original would have.

Now I am not an electrical engineer so please don't pick apart my diagram for symbol correctness.

I wish I could find a diagram for the original sentry and I'm certain it could be duplicated easy peasy

 

 

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Ahh the "Sentry" Biggest POS in the history of tractors... YES crap CAN THAT THING!!! I did a 5088 25 years ago and its still going on the same relay and trans clutch packs almost 10,000 hours later. The sentry's biggest stupidity is the fact that it locks in two gears at once EVERY time you make a shift. It has to sense oil pressure on the engaging clutch BEFORE it will let go of the disengaging pack. Just wire up a single relay using one NO contact for one clutch and the NC contact for the other. I used a 30 amp bosch relay from a chevy truck.  I did not use a timer at all. let go of one solenoid and grab the other one that's all you need to do. There will be a slight lag in the shift at low engine rpm and especially with cold oil but that's about it.

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I got to thinking about this a few months ago to.  It's not really all that complicated on how the sentry works.  I think you could get a Audrino controller and set it up to control the trans.  I'm not familiar enough with one to get it going at the moment but someone who is shouldn't have a problem.  

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I have a manual explaining the operation of the Sentry, the timer is crucial to the operation in case a clutch does NOT release, I can email the manual to you if you supply an address.

I always figured a small PLC would be easy to wire in and the logic could easily be made to function as the Sentry does.

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30 minutes ago, superih said:

I have a manual explaining the operation of the Sentry, the timer is crucial to the operation in case a clutch does NOT release, I can email the manual to you if you supply an address.

I always figured a small PLC would be easy to wire in and the logic could easily be made to function as the Sentry does.

That would be great! I hadn't thought of using a arduino like someone suggested. That may be the best plan.

 

Zachgrant08@gmail.com

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Thanks to Luke I got the explanation of the sentry module and also a wiring diagram for it.  I am confident now that I can make this work, with a few alterations to my original drawing. Thanks guys.

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Can you take the original apart and check the solder joints, resistor, capacitors to see if anything is wrong?

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1 minute ago, BOBSIH856 said:

Can you take the original apart and check the solder joints, resistor, capacitors to see if anything is wrong?

Good point. I would think if your smart enough to build one you could fix the original and possibly even improve it?

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14 minutes ago, BOBSIH856 said:

Can you take the original apart and check the solder joints, resistor, capacitors to see if anything is wrong?

I'm sure I could take it apart, but from what I understand they use some sort of a logic board, and I haven't been able to find a schematic for that. So, unless it is a very simple board built off of a breadboard, I'm not certain I could figure it out.

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14 minutes ago, Delta88 said:

Is the patent still valid?

If it is this throws a wrench in the reproduction of these depending on how it is protected by patent

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14 minutes ago, Delta88 said:

Is the patent still valid?

I'm not sure... Why?

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Just now, bitty said:

If it is this throws a wrench in the reproduction of these depending on how it is protected by patent

I don't plan on building these to sell.

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There would be a market for them; small but still a real need. At over $2000 from CaseIH its cost is close to 20% of the tractor in some cases.

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1 hour ago, Delta88 said:

There would be a market for them; small but still a real need. At over $2000 from CaseIH its cost is close to 20% of the tractor in some cases.

That's exactly where I'm at. I gave $6500 for the tractor. I can't justify putting $2300 into a sentry.

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Did the IH patents go with Navistar or CIH? It’s been 33 years now...

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I revised my drawing a little after reviewing the wiring diagram. I see now that it uses a switched ground in most places instead of a switched 12v+. 

I went ahead and ordered the weatherpack connectors to plug into the existing harness. I need to research a little more and decide weather to use time delay relays or a Arduino board. From a simplicity standpoint, I think the relays would be the easiest way to go. But, with an Arduino I should be able to maintain function of the sentry light and different time delays.Untitled.thumb.png.17864de5fa706862fb68c18ccef50a3b.png

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I hope you get it to work but will it protect the trans like it was suppose to originally   and there is forsure a need for this

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28 minutes ago, 89vmax said:

I hope you get it to work but will it protect the trans like it was suppose to originally   and there is forsure a need for this

It will not apply pressure to either shift solenoid until pressure has dropped off in the other.

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7 hours ago, bitty said:

If it is this throws a wrench in the reproduction of these depending on how it is protected by patent

https://www.stopfakes.gov/article?id=How-Long-Does-Patent-Trademark-or-Copyright-Protection-Last

 

I'd say he's safe

 

While you mentioned that you do not intend to build these for sale, you might keep your records and parts resources. As mentioned above the market is very small for these, but still necessitated if you have a quality product that works and still provides adequate transmission protection.

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2 hours ago, ZachGrant said:

It will not apply pressure to either shift solenoid until pressure has dropped off in the other.

That is NOT how it worked originally. But you are on the right track.

 

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25 minutes ago, ESE Machine said:

That is NOT how it worked originally. But you are on the right track.

 

Care to elaborate? I'm still trying to understand how they worked from the factory. That is what I gained from reading the service bulletin.

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Mike and I have talked about this very thing for a few years now , the problem is we are to far apart to sit down for a couple hours and do what your talking about . I like your thinking 😊😊

Danny 

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17 hours ago, ZachGrant said:

Care to elaborate? I'm still trying to understand how they worked from the factory. That is what I gained from reading the service bulletin.

I think if it waited till the pressure dropped then when the tractor was under load, if you down shifted or up shifted, it would stop moving? This would then put a lot of shock load on the transmission. Didn't the sentry keep pressure on while shifting?

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