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Wheel Horse 312-8 Pto Safety Switch Problem


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#1 FilledTires OFFLINE  

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Posted July 05, 2014 - 02:49 PM

Hi Everyone,

 

I have a Wheel Horse 312-8 I am almost finished with restoring.

 

I am having a problem with the PTO Safety Switch. When I pull the PTO Lever, the engine's power get's cut.

 

I have examined the switch without removing it, and all the leads look ok.

 

Can someone tell me exactly how the PTO safety works?

 

I understand that when you push the PTO lever forward to engage, The PTO Lever leaves the contact point on the safety switch. I am guessing this is suppose to prevent starting when the PTO is on.

 

How does the power get transferred through the safety switch when I engage the mower deck?

 

If you can help me understand how this works, I can perhaps figure this out.

 

Thanks in advance!


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#2 FilledTires OFFLINE  

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Posted July 05, 2014 - 03:09 PM

So I decided to take a multi meter to the switch and figure this out. I answered my own question.

 

The answer for future people is the switch transfers power from one set of terminals to another when the switch is activated or deactivated. My switch for example has 6 Terminals. 3 on the left side, and 3 on the right side.

 

When the PTO Lever is in the disengaged position, the Right Terminals are connected and running power. When the PTO Lever is in the Engaged Position, the Left Terminals are running power.

 

My switch is bad and only the terminals on the Right side are working.

 

I ordered a new switch on ebay.


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#3 JDBrian OFFLINE  

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Posted July 05, 2014 - 03:34 PM

That's a common problem with many brands of tractor. I managed to take the switches apart and fix them on my JD314 and 317. They are electric PTO and the switch performs the safety function and sends PTO power to the clutch. In many cases these defective safety switches end up getting bypassed. It's much safer to fix it like you are doing. 



#4 GWest OFFLINE  

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Posted July 05, 2014 - 04:58 PM

1/2 of the pto switch controls the starter circuit and the other 1/2 controls the ignition. Both are just 1 of the switches in series in each circuit. If this throws any doubts into your conclusion post the tractor's model and serial number and will try to locate detailed wiring diagrams. There were quite a few changes in the 312-8 wiring over the years.

 

Garry


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#5 OkieDokie OFFLINE  

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Posted July 17, 2014 - 12:31 PM

I also am restoring a 1990 312-8 Toro Wheel Horse garden tractor... Serial #1923015603.. My problem isn't with a switch but with blown fuses.

 

I have looked and looked for the schematics for this particular tractor to no avail.  I needed to replace the starter in it and had a heck of a time getting the correct replacement for it.  Finally just had to take the bad starter right in with me

to get the correct one.

 

The mower works and runs just fine except it keeps blowing the fuse.

 

I believe I have finally found a place that understands my frustration lol.  So thankful to have found this site and forum.

 

Any help would be greatly appreciated on this.

 

Stoney



#6 MolonLabe OFFLINE  

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Posted July 17, 2014 - 05:43 PM

I also am restoring a 1990 312-8 Toro Wheel Horse garden tractor... Serial #1923015603.. My problem isn't with a switch but with blown fuses.

 

I have looked and looked for the schematics for this particular tractor to no avail.  I needed to replace the starter in it and had a heck of a time getting the correct replacement for it.  Finally just had to take the bad starter right in with me

to get the correct one.

 

The mower works and runs just fine except it keeps blowing the fuse.

 

I believe I have finally found a place that understands my frustration lol.  So thankful to have found this site and forum.

 

Any help would be greatly appreciated on this.

 

Stoney

I have a C-161A that did the same thing, it was caused by chaffed insulation rubbing the shroud by the starter. A fuse and a little tape and it now runs fine. Good luck!






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