My finish mower has a puzzling design IMO.... from above…the blades rotate clockwise…. But they are attached with LEFT hand threaded bolts. No lock washers. No safety wire. Just a plain washer under a 14mm LH bolt.
Not knowing this, at about 5 hrs operation (new) the center spindle seized …. presented as squealing and smell of burning rubber. I contacted the seller and they quickly shipped me a new spindle and new belts.
As I disassembled it….my first error was to use my pneumatic impact to remove the bolt…and SNAPPED it…because I had no ideal it would be a LH bolt. (Think about this…. if the blades rotate CW ….. the bolt (entering from beneath) should be an ordinary RH thread)….or it would tend to loosen due to resistance against the grass…. right? The spindle drives the blades and the bolt… and it is driving a LH bolt in an UN-threading direction! I guess the chineese are on the opposite hemisphere AND the lower hemisphere as well…??)
So I called back and they sent spare bolts. (Ever try to find 14MM X 1.5 pitch LH Bolts Locally? Fastenal has them…. for $4 each…and will happily sell me a bag of 100 …their smallest quantity.).
OK…back together and mowing just fine. Put it away for the winter.
Now comes Spring 2021 and while mowing I notice the center blade is not mowing as cleanly as the outer two blades. I figure that’s due to high grass and do a second pass…. but no improvement…
THEN the darn thing starts RATTLING and VIBRATING but only about 2 or 3 seconds every 10 seconds. …and the mowed area is having a worsening effect from the center blade. I take it o the shop and raise the mower…place a jackstand beneath it for safety and crawl under….
The center blade is freely spinning on it’s spindle/boss because that LH bolt is LOOSE by about 3 threads. AND when tightened the blade still has a loose fitment…. EASY to spin by hand while the spindle is unmoving. I remove the bolt and realize the flat washer has a concave shape…so I reverse it to a cone shape and reinstall that LH bolt with the impact wrench….. and THINK I’m thru….when I decide to TEST it again for tightness against the spindle by spinning it by hand again…and realize the blade is facing differently than the outer two blades…
YEP. I’ve installed it upside-down, just like the johnjk (the OP) demonstrated in #1 post. DOH!
Finally got it put back together and took the rest of the day “off”. (Beer:30)