NH 451 mower head assembly

[DogT]

Belt broke on my 451 mower because the grass got in the sheave under the v-belt, so while it was off, notice the crankshaft assembly and sheave are loose. So I get the puller out and luckily it was easy to get off with a little heat, but I could not get the cup or cone of the tapered roller bearing out of the rear of the unit over the cranksahft. Does this thing have to come out the front? It seemed like it was about to come off the crankshaft, but never would. There was a small rubber piece left of the oil seal, I probably need a new one of those. I cleaned it up as good as I could and it seemed to go back in with no play with the special castle nut. With the knife blade off the assembly it was running smoothly by hand. Book says to tighten the castle nut so it takes 2 ft/lbs to turn the assy. I shot some grease in the bearing as good as I could.

But could someone tell me if this bearing should come out the rear or do I have to take it apart from the front? I'll get a new seal and install it. There was a lot of grass packed in the bearing area, I've never adjusted this thing for 10 years or more, now I've got it apart I put lots of anti-seize on the items and plan to keep an eye on it.

 

[DogT]

OK, here's how it works. It was obvious once I got the replacement seal. The old seal had come apart, the rubber part fell out, the metal ring was still there. I pulled the old metal ring out from the outer perimeter, cleaned the area, pressed in the new seal, a 2" piece of PVC worked fine once it was started. The castle nut front face bears on the bearing cone and sets the tension. The ID rubber part of the seal, seals over the outer diameter of the castle nut after it's installed. That's it. Done and belt is back on with the bearing/sheave now not loose. I should probably check this at the beginning of every season, it's easy enough now that I've put anti-seize on everything.