Shaft on Hydraulic Pump at Pully broke - Model 853

[Rambler]

The shaft on the Hydraulic pump broke off where the nut holds the drive belt Pully on to the shaft. I Must have hit the nut just right when I was tapping it to loosen. I was able to put the nut back on, but is being held in place with only three threads. The pump has no leaks with only 1400 hrs on the machine. A replacement shaft is no longer available from bobcat and so far I have not been able to locate an aftermarket shaft to replace it. I am thinking of having a welding shop use a Tig welder to weld the Pully directly to the shaft and eliminate the nut. I am concerned welding may weaken the shaft. Will this Work? Any recommendations? Thank you, Greg

 

[Tazza]

Contact loader parts source to see if they can help with a shaft.
Welding the shaft to the pulley may work, my only concern is the heat may damage the seal and if it leaks after welding, you can't change it.
If it's just the threads that have gone, a machine shop could tig it and re-cut the threads. Without seeing it, i can't be sure, but there is a possibility that a new thread could be cut on what's left and use a smaller nut and a washer to hold it on.

 

[Rambler]

Contact loader parts source to see if they can help with a shaft.
Welding the shaft to the pulley may work, my only concern is the heat may damage the seal and if it leaks after welding, you can't change it.
If it's just the threads that have gone, a machine shop could tig it and re-cut the threads. Without seeing it, i can't be sure, but there is a possibility that a new thread could be cut on what's left and use a smaller nut and a washer to hold it on.

I am going to see if the machine shop can mill out the center of the Pully 3/8 of an inch to provide more threads for the nut to grab. The nut will then be recessed in the Pully. Then have them tack weld the nut to the Pully to keep it from moving. Hopefully the pully is not cast iron, but steel to match the shaft metal. To have a new shaft installed a Hydraulic shop wants $2500.00. I don't have a place clean enough to dismantle or the knowledge to take it a part and put it back together

 

[flyerdan]

I am going to see if the machine shop can mill out the center of the Pully 3/8 of an inch to provide more threads for the nut to grab. The nut will then be recessed in the Pully. Then have them tack weld the nut to the Pully to keep it from moving. Hopefully the pully is not cast iron, but steel to match the shaft metal. To have a new shaft installed a Hydraulic shop wants $2500.00. I don't have a place clean enough to dismantle or the knowledge to take it a part and put it back together

Having a quick look at the online parts catalog, I'm assuming that you have shaft 6666221, which has a taper with a woodruff key and threaded end, like a lawnmower flywheel end.
Since the repair has to be done in situi, your idea of pocketing the pulley for the nut to recess in is probably best. With adequate pictures, measurements and descriptions, you shouldn't have to take the machine to the shop, just the pulley.
Rather than tack welding the nut, I'd suggest using red loctite* on the threads and back of the nut to pulley contact area. As Tazza pointed out, the heat could damage the seal, and even though there would be far less on a tack, and the locktite can be dissolved with heat without damaging the threads any more. I would replace the castle nut with one that has the washer attached so you have more surface area for contact.


*not sure if it's red or blue that releases with heat, someone correct me if I'm wrong and I'll fix it.

 

[craigb93]

Having a quick look at the online parts catalog, I'm assuming that you have shaft 6666221, which has a taper with a woodruff key and threaded end, like a lawnmower flywheel end.
Since the repair has to be done in situi, your idea of pocketing the pulley for the nut to recess in is probably best. With adequate pictures, measurements and descriptions, you shouldn't have to take the machine to the shop, just the pulley.
Rather than tack welding the nut, I'd suggest using red loctite* on the threads and back of the nut to pulley contact area. As Tazza pointed out, the heat could damage the seal, and even though there would be far less on a tack, and the locktite can be dissolved with heat without damaging the threads any more. I would replace the castle nut with one that has the washer attached so you have more surface area for contact.


*not sure if it's red or blue that releases with heat, someone correct me if I'm wrong and I'll fix it.

If you are successful in boring the pulley for more clearance for the nut think about finding or making a soft metal flat washer that is big enough in OD to bend it over a flat on the nut to lock it in place. 16 or 14 gage(0.075") plate would be fine. You could dress the nut seat that much and not lose any thread engagement. No heat damage potential and reusable. -Dick

 

[Rambler]

If you are successful in boring the pulley for more clearance for the nut think about finding or making a soft metal flat washer that is big enough in OD to bend it over a flat on the nut to lock it in place. 16 or 14 gage(0.075") plate would be fine. You could dress the nut seat that much and not lose any thread engagement. No heat damage potential and reusable. -Dick

Great ideas flyerdan and craigb93. Did not think of using the red locktite and the washer to lock it. Thank you