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PTO shaft school please


Twolines
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Im no stranger around equipment but have never needed to choose or cut a pto shaft. 

I picked up a small brush hog last fall and am hooking it up today. Its an MK pulsar. I hooked it up to the 3 pt raised it up and took a measurement from bolt hole to groove on pto shaft 50¾". The shaft that came with it is 38" from bolt hole to the quick snap deal fully collapsed. With it extended i figure this leaves me with about 11" overlap. The manual says it needs to be overlapped half the length but then says minimum 6"?? It also refers to pulling measurements from hole to hole but then shows a diagram with the measurements taken of just the slip joint. If i measure just the shaft its 24" making my 11" almost half over lapped...lol sounds like i might need a longer shaft??

School me, thanks.

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If you use the 11 correctly you have no need for more shaft...

You'll gain some when lowered and not under load when raised.

Move 3 pt pins on mower back to the other mounting hole to shorten distance between tractor and mower and gain some overlap if you are concerned .....

 

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It came with the pins mounted in that top hole and says nothing about the lower hole i wondered about that as u can plainly see it would suck it in a bit.

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All of what NoMoreJohnDeere says----in my the '60s and 70s, I represented Howard Rotavator here in the mid-south (pto tillers).

Dimensions and geometry of the 3 pt lift for different tractors will  vary from brand to brand.

The Danger of  telescoping too far and hitting the dead end of telescoping action is placing pressure on the implement and/or tractor PTO shaft.

I have seen more than one tractor PTO shaft pushed back into the tractor transmission  housing.

Conversily----not enough engagement (overlap) of the male/female shaft will allow the shaft to wiggle---twist until the two pieces strip each other and possible disengage each other-----similar to a socket not engaging enough shoulder of a nut.

Probably worth your while to try the middle hole just to see where you are.  I always preferred the shorter shaft for strength.

Good luck------keep her greased!!!

 

DD

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With implement at its highest point you need  one inch of free travel on the drive shaft when it is  hocked to PTO.  With the shaft off of the PTO fully compress the shaft make a a mark on the shaft at the end of the coupler hock it to the PTO make another mark it again that is your free travel. This should give you the overall length for the drive line make sure it is where you wont it mounted on the tractor.  

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One other commonly overlooked point on PTO shafts:

The u-joint knuckles should be "in phase" with each other.  Knuckle slipping onto tractor shaft should be in exact alignment with knuckle slipping onto implement g-box shaft.

Out of phase will cause severe vibration  as the implement follows over uneven terrain or is over lifted.   Purpose of the flexible shaft is for one knuckle to slow down while the other speeds up in the opposite direction angle so the the speed on the output end of drive shaft remains constant.

Worth noting-----the tractor PTO shaft and input shaft should sit in a near level plane with each other when working or in lifted position.

Not a safety recommendation-----but cut the plastic safety shields off and grease often until grease comes out all 4 corners of the cross assembly.

Good luck again.

 

 

DD

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3 hours ago, Delta Dirt said:

Not a safety recommendation-----but cut the plastic safety shields off and grease often until grease comes out all 4 corners of the cross assembly.

Why cut the shields off?   

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3 minutes ago, dannyredfan said:

Why cut the shields off?   

Most of the time, the small access hole provided for getting to the grease fitting is barely big enough and even then its hard to see if you're actually doing anything or just randomly pumping grease into the cavity. 

I don't recommend cutting or removing a safety shield but I see the reason for it. There is also no good reason for any body or body part to be near that area when the machine is running anyway.

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Agreed  on keeping  away. 

   But just food for thought, couldn't you just make a bigger hole? 

Iam not the first guy to jump on to safety,  but I hate to jump from it.  

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Ok, ran it how i had it hooked up in the pic(covers back on). Called the dealer i bought it from and he said run with the 11"...gave me his word he'd cover it if anything happened...lol. Mowed most of the field, some big stuff in there i didnt notice before. I tried to avoid the stuff bigger than an inch even tho the manual said 1 ½. Did break the chain that goes from the top link to the back of the mower...dont know what happened. I was parked, mower down and i fired it up, lifted the mower for transport and bang! I found one link completely spread open laying on the mower deck. Ill be replacing the chain with something better quality.

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About lubrication...when i had it apart, i greased both u joints, the shaft and the collars for the tube covers. I can see where a guy would want to cut them off as they do not allow a grease tip at all. I will be customizing the holes when im done mowing.

Another question. Anyone sharpen their blades? These were fairly blunt to start with but it did seem to cut well.

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16 minutes ago, Twolines said:

These were fairly blunt to start with but it did seem to cut well.

Bh is generally blunt ....1/4" as you will be hitting scalping digging etc at least the first 6x

most late model factory/supplied shafts are phased with a fits only 1 way slot or 180

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Ya the two halves of the shaft i have are one way. Didnt pay attention if they are in phase or not. Didnt vibrate tho, ill check tomorrow before i start back on the field.

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