bumperm
Veteran Member
As delivered new, the bottom dipper stick pin (the one that goes through the mechanical thumb pivot, the bucket holes, and the bottom most hole in the dipper stick) was quite difficult to remove or reinstall when changing buckets. I should have inspected it more carefully, but wrongly assumed the weldment on part of the assembly, probably the thumb, must be slightly out of alignment and causing the problem. Wrong.
After removing the offending pin using an air hammer (actually an aircraft rivet gun), I noticed something odd with one of the 28mm by 25mm bushings in the end of the dipper stick, part of one bushing was broken out and laying loose, held in place by grease! I removed the loose piece and determined there were no sharp edges to screw up the pin. Still, I wondered why did the bushing fail like that?
Looking at the hole in the pin for its retaining bolt, someone had obviously used a punch to align the hole when putting on the bucket (nothing inherently wrong with that, as long as you get the punch in the hole!). The punch had damaged the edge of the hole, causing the metal to flow so that it slightly increased the OD of the pin at that point. I removed the material that was proud using a 1" wide belt sander. Then reassembled the hoe as I needed it for a job while awaiting a new bushing. Pin slid into place easily with no issues.
When the new bushing arrived, a removed the old one using a 5/8" rod as a drift, working through the opposite bushing. No problem removing it without heat. Prior to installing the new bushing, I cleaned and inspected it's hole in the dipper stick, removing some orange paint that was located exactly under where the broken portion of the old bushing was located. While the paint may not have caused the failure, it likely didn't help matters. Smoothed the hole with a scrap of 600 wet/dry and then lightly lubed surface. I had previously put the new bushing in the freezer to help things along, and briefly considered using a heat gun on the end of the dipper stick - - but then thought WTH, I'll try it at ambient temperature first. Using the pin as a guide through the bushing on the other side of the dipper stick, and just through the hole where the new bushing would go (to help keep the new bushing driving straight), I slid the new bushing on the pin and wailed away at it with a soft faced dead blow hammer. It smoothly went into place, about 1/64 to 1/32" at each blow. Yeah, I should have used the heat gun, but I got it in without screwing it up :thumbsup:
If there is a moral to this story, if your hoe pin is difficult to R & R, check it for damage at the retaining hole. That extra bit of width due to a boogered up hole can certainly fail the hardened and brittle steel bushings . . . the pins, although hardened as well, are not nearly as hard as the bushing.
bumper
After removing the offending pin using an air hammer (actually an aircraft rivet gun), I noticed something odd with one of the 28mm by 25mm bushings in the end of the dipper stick, part of one bushing was broken out and laying loose, held in place by grease! I removed the loose piece and determined there were no sharp edges to screw up the pin. Still, I wondered why did the bushing fail like that?
Looking at the hole in the pin for its retaining bolt, someone had obviously used a punch to align the hole when putting on the bucket (nothing inherently wrong with that, as long as you get the punch in the hole!). The punch had damaged the edge of the hole, causing the metal to flow so that it slightly increased the OD of the pin at that point. I removed the material that was proud using a 1" wide belt sander. Then reassembled the hoe as I needed it for a job while awaiting a new bushing. Pin slid into place easily with no issues.
When the new bushing arrived, a removed the old one using a 5/8" rod as a drift, working through the opposite bushing. No problem removing it without heat. Prior to installing the new bushing, I cleaned and inspected it's hole in the dipper stick, removing some orange paint that was located exactly under where the broken portion of the old bushing was located. While the paint may not have caused the failure, it likely didn't help matters. Smoothed the hole with a scrap of 600 wet/dry and then lightly lubed surface. I had previously put the new bushing in the freezer to help things along, and briefly considered using a heat gun on the end of the dipper stick - - but then thought WTH, I'll try it at ambient temperature first. Using the pin as a guide through the bushing on the other side of the dipper stick, and just through the hole where the new bushing would go (to help keep the new bushing driving straight), I slid the new bushing on the pin and wailed away at it with a soft faced dead blow hammer. It smoothly went into place, about 1/64 to 1/32" at each blow. Yeah, I should have used the heat gun, but I got it in without screwing it up :thumbsup:
If there is a moral to this story, if your hoe pin is difficult to R & R, check it for damage at the retaining hole. That extra bit of width due to a boogered up hole can certainly fail the hardened and brittle steel bushings . . . the pins, although hardened as well, are not nearly as hard as the bushing.
bumper