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Mike56073

656 PTO pin

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Rebuilding the PTO on my 656 gas.  Got everything cleaned and resealed.  I went to bench check the piston/clutch pack on the workbench with shop air, and had nothing.  I found that the small pin in the control valve(that I had just replaced) was missing.  Now I have to take it all apart to find the pin(assuming it’s in a passage somewhere)

      When I first replaced that pin it was a fairy loose fit, even with a new pin.  Is this correct, or is it supposed to be a tight fit(like a roll pin)?

 Also,  what is the pump pressure spec?

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There should be a press fit in the thin rod that retains the lower springs. 
 

  In the past, I used to replace that rod but they have gotten quite expensive so I just crush it a little on the sides so the pin fits tighter.  I have never had a failure of the pin when I’ve done it this way. 

i doubt that you will find that pin.  I have overhauled many pto’s where the pin had been broken and I have never found the pin in the pto unit. 

I set the pressures to 235#

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3 hours ago, Red Tech said:

There should be a press fit in the thin rod that retains the lower springs. 
 

  In the past, I used to replace that rod but they have gotten quite expensive so I just crush it a little on the sides so the pin fits tighter.  I have never had a failure of the pin when I’ve done it this way. 

i doubt that you will find that pin.  I have overhauled many pto’s where the pin had been broken and I have never found the pin in the pto unit. 

I set the pressures to 235#

Thanks for the reply! 
I’m going to look for the pin tonight,  it has to be in the unit, it hasn’t left the bench since I replaced it.  I’m wondering if a regular roll pin would fit tighter.

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Found it!!

629E8049-7E0D-43D8-91E2-109B295B4E27.jpeg

A7E774C9-70C4-4911-920B-8A881260AD5F.jpeg

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I got the PTO all back together.  Went to check pressure on it, the initial engagement is 45 psi, which is good.  The full engagement, however is only 135.  I then disconnected the linkage and manually lifted the valve up, and got 210.  Better but still not in spec.  So I know I need to get a new triangle piece and shoulder bolt, but still can’t figure out why I can’t get 235 out of it.  Any ideas?

      When I air checked it on the bench it didn’t sound like it had any major leaks, so this is a surprise to me.

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My guess would be that the lower spool has got a little extra clearance.  I think you will be just fine with 210 lbs.  The original spec on those pto's was 195 lbs.

Those spool assemblies have gotten crazy expensive so I would just go with the 210 lbs.   Those tractors are not putting out all that much horsepower.    Of course you will have to fix the linkage so that you can get full travel.

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Also, most likely it has the original lower pressure spring and spool.  Does it have a lock nut(newer style spool,higher pressure) on the adjustment and a washer about 1/8th inch thick or does it have a thicker spacer and no lock nut.   At any rate, 185 was original on an 806 so you don't have to get near that 235 on a 656. 

Lucky on finding that pin where you did. 

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Is this our so called Judas pin as I've heard it called here before? 

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10 hours ago, pete23 said:

Also, most likely it has the original lower pressure spring and spool.  Does it have a lock nut(newer style spool,higher pressure) on the adjustment and a washer about 1/8th inch thick or does it have a thicker spacer and no lock nut.   At any rate, 185 was original on an 806 so you don't have to get near that 235 on a 656. 

Lucky on finding that pin where you did. 

It has the thicker spacer washer as compared to my 686

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31 minutes ago, Mike56073 said:

It has the thicker spacer washer as compared to my 686

Then it has the low pressure spool and spring.  I saw a lot of 656 tractors that were difficult to even get the 185  psi but worked fin e.  

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49 minutes ago, pete23 said:

Then it has the low pressure spool and spring.  I saw a lot of 656 tractors that were difficult to even get the 185  psi but worked fin e.  

Ok, thanks! 👍

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I believe I need to replace that pin on my 656.....I have yet to drum up the ambition/courage to take care of it.  I've heard it is a fairly easy thing to fix.  Glad you found the pin and all ended up fine!!!

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On 1/17/2020 at 4:52 PM, Mike56073 said:

Found it!!

629E8049-7E0D-43D8-91E2-109B295B4E27.jpeg

A7E774C9-70C4-4911-920B-8A881260AD5F.jpeg

lookd like to me the blue seal ring is cut  

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6 hours ago, hardknocks said:

lookd like to me the blue seal ring is cut  

I dont think it was cut.  I started out with 2 new ones that were blue, but i ended up cutting one of them.  I replaced the one with another new one which was yellow.

anyways, its all back together along with a new piece of linkage(triangle piece and shoulder bolt).  I got 200PSI exactly.  I put it on my 8ft snowblower and relocated some snowdrifts on Sunday, and it works beautifully.

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