Backhoe new 4672 A backhoe problem

wstacy · Oct 14, 2003

I've only put a few hours on this and already one of the boom lock pins is missing in action. /forums/images/graemlins/frown.gif It's the one closest to the operator, and it seems to have ripped out. Is this thing just pressed in or what? I cant find it, so I'm not sure how it attaches. The parts diagrams are not very helpful. It looks to me like the pin does not mate up with any hole or anything on the other side of the boom. The lock itself is bent and I'm not sure how or what I did to do that. Any ideas?

boustany · Oct 14, 2003

There are 2 boom lock pins (sort of) I can think of. One is for rotation (left/right), which just drops down by gravity into a receiving hole once the spring pin is removed. The other is for the up/down, which holds a sort of link about 8" long with one 3/4" hole at each end. That link basically spans 2 3/4" pins, and is held in place with 2 spring clips, when the boom is all the way up to prevent 'droop' during transport. My link lasted about 1 week: its not designed to tolerate, for instance, bumping into a pile of eath with the hoe whilst loading.

My brother made me a new one.

Are these what you are referring to?

wstacy · Oct 14, 2003

Yes, it's the strap that connects the two pins that got bent and one of the pins with its cotter got lost. It looks like this pin (closest to operator) could also be a travel stop for the boom's upward travel, except that such a pin would logically penetrate the opposite side of the boom, and there is no such hole. So I'm thinking it's a real short pin and am not sure what its attachment to the boom is (guessing pressed in since I see no evidence of threads). I can hammer the strap straight, but need the part I.D. for that pin and its fastener if any. Sounds like this is a very tender and maybe useless item? /forums/images/graemlins/mad.gif

GregJ · Oct 14, 2003

Wstacy,
I have attached a photo, actually 3, of my 4672. It shows it locked in position and then a front view and back view of the pin (I think) you are describing. The pin is welded and flush on the back side. Hope this helps.

Greg

boustany · Oct 15, 2003

That pin should have been very firmly welded into place - I scrapped the link and the pin(s) on my hoe weren't even scratched. It seems to me possible that the weld and/or assembly was defective. Maybe it was tack-welded into place and forgotten. As the photos show, there should be quite a weld fillet (or whatever you call it) if the pin tore off.

You might consider contacting the dealer and or Kubota for a warranty claim.

If this isn't an option, have a machine shop make a clone of the other pin (basically a 3/4 dowel welded onto or through a 1/4 plate) and have it arc welded into place.

hayden · Oct 20, 2003

MIne came out too, but it was clearly my fault. I tried moving the boom to install the BH without removing the lock strap, and it pulled ou the pin. I still haven't tried to reinstall it.

boustany · Oct 20, 2003

Well I'll be....

Mine came out this weekend. Its not our fault - its a lousy design. The pin is lightly welded from the back. They might as well have peaned it on! /forums/images/graemlins/mad.gif

I will follow my own advice and make a plate/pin that'll be welded together, then installed and welded from the back, and the plate will be be welded on. Other than a crash, there is no reason this should have come out. /forums/images/graemlins/mad.gif

wstacy · Oct 20, 2003

Kubota now admits it's a defect. That little pin must be flush on the inside of the boom, and needs a substantial weld/plate on the outside just like the more aft one. They are sending a replacement part to my dealer, who hopefully will come out with a portable welding rig and make it right under warranty. I will report back if/when this all happens. /forums/images/graemlins/smile.gif

boustany · Oct 20, 2003

Please do let us know how it goes - and a part number if you get one. My backhoe is outa warranty, but I can try and get them at least to give me the replacement part.

GregJ · Oct 20, 2003

I was talking with my dealer today and brought up this issue. He said this is a fairly common problem. He also said that they don't cover it under warranty. He brought up the point that the pin is made to break out when enough force is exerted on it to protect the boom & dipper from being damaged. Basically the pin is designed similar to a shear pin. So far I think I have been lucky. Even the dealer said he had accidently tried to use a BH with it in the locked position. I am definitely going to try to be more careful in the future though.

Thanks for the post,
Greg