PTO Shaft mod from an older snow blower. trying to get shear protection in place.

[pmsmechanic]

I can understand your concern but with 18 PTO horsepower and that size of a PTO shaft I don't think you need any protection. The engine will stall long before anything breaks. Just my opinion. Don't take me wrong on this I'm just saying that I don't think you don't have anything to worry about.

 

[RoyBrooks]

I can understand your concern but with 18 PTO horsepower and that size of a PTO shaft I don't think you need any protection. The engine will stall long before anything breaks. Just my opinion. Don't take me wrong on this I'm just saying that I don't think you don't have anything to worry about.

I have the 48" model of this blower and have had the input shaft shear pin go on a number of occasions. Its not fun trying to get the tractor stopped before the shaft does some damage. It might be because of the 3 blade fan allowing more snow to be pushed in to each blade, that it puts more stress on the 5/16 bolt? but you can hear each blade as it picks up the snow.

 

[doxford jim]

I have had the shear pin fail on my larger 73" blower driven by the 55PTO HP Jinma ( running at 720 rpm instead of 540 rpm) and all that happened was the input shaft to the blower stopped turning.

I doubt that the 18hp will cause much damage and stopping the tractor engines immediately, would be the first thing to do.

Caution is very commendable and necessary, but an over active imagination not so good.

Of course the flailing of the PTO shaft is not good, but the chances of the shaft disconnecting completely are pretty remote - but anything can happen I guess.

Jim

 

[pmsmechanic]

I stand corrected and I don't mind. I bought a used John Deere model 59. It came without the short PTO shaft in front. John Deere always seems to want ridiculous money for those kind of parts so I'm having a PTO shaft made for a little more than half the price at the dealer and yes it's getting a sheer bolt. The problems of users on this forum on their lack of sheer bolt protection encouraged me to do it. I'll post a picture once I have the drive shaft.

 

[RoyBrooks]

I broke another shear bolt on the blower, to keep the shaft from coming off again I ground a slot in the input shaft to the gearbox. I then added a small ground down 3/8" bolt to ride in the groove. The hope is that it will keep the pto shaft on the gearbox input shaft if or when the shear bolt breaks again

 

[doxford jim]

I like what you are trying to do. I am surprised that the PTO shaft came off of the blower - I know in the case of my blower it has never come off the shaft - when the shear pin fails, the tractor PTO output shaft keeps turning and all power to the blower stops.

What sort of angle does your universal shaft sit at when using the snow blower - that might have something to do with problem. I have learned as I have gone along and don't profess to know that much, but I do know that the shaft angle affects the loading of the two universal joint and thus, the end result.

If you get the shear pin arrangement sorted out, I would take a good look at the two universal joints. Are they loose at all - they look to be well used in the photograph and could be original. If I was using your blower, I would worry about those failing at some time in the future. The replacement parts are cheap and should give you more peace of mind if replaced.