View attachment diag.pdf No 33 decided it had enough and broke in half and wiggled out. Thank goodness the other part was kept in place by the flange screw. It's a bit strange a pin of that diameter made no sound when it broke or perhaps the noise of the engine covered the sound when it broke. The operator picked up the broken half from the hole he was digging and handed it to me while my heart sank thinking more moolah to be spent on repairs There seems to be what I think are 'bubbles' where it broke in half. Am I correct to assume there was air trapped in the pin which made it inherently weak and prone to splitting ? I will have pics up by tomorrow evening. It was too late for me to go to the dealer in the afternoon so I pretty much popped the broken half of the pin back in and told the operator to take the BL71 on level ground. We're working on a new contract where the job involves spreading rocks (200mm to 600mm) to create a base for a new road that leads up to a terraced part of mountain. I told the operator more than once not to bash the back of the bucket on the rocks to compact them. + Told him to put the weight of the machine while pressing down with the bucket instead (is that right or wrong?) Anyhow, could the constant bashing be the reason why the pin broke or the weakness inside the pin would have ended in a broken pin sooner or later? As always, many thanks for your opinions and advice Spangles
Not sure the best way to compact rocks on I assume a steep grade. The bubbles your looking at could very well be an old crappy weld repair. Get a new pin and don't let your operator hammer the machine to death. 200mm = 7.8" to 600mm = 23.6" That must be the base depth?
The grade varies between 5 and 10%. Some parts are easier than others to do. 200mm to 600mm are the rocks we are being delivered to make the base for the road. Will get the 12 ton roller on it, if it does not slide off that mountain slope and into the ditch that is. After that, we'll have crusher run spread and then another round of roller. Hmm weld repair on a pin? It does not look like that. You'll get a better idea once I get it all out and take pics. Went to the dealer today and I was quoted 325 pounds :/ That's a bit steep...was thinking it would be around 150...or am I wrong and it really costs that much? Thanks for your opinions and advice Spangles
What machine are we talking about here..? Post some good photos including some in focus close-ups if you can get them. The break sounds interesting ........
Volvo BL71 S/N 1031 bought in U.K & currently working in Mauritius. Sorry, I won't have pics until the new pin arrives and I can take the old one out. I will for sure make some very good pics including close ups so that anyone who's way more experienced than I can tell me what they think caused the break. I'm still baffled how a pin that size would split exactly in half :/ Thanks for your opinions and advice Spangles
It would not take me a second time to tell the operator not bash the rocks with the machine .He would be gone . Backhoes don't have any give .They are solid right through to the frame more so with the riggers down .
I am not going to keep him on. The job has already been advertised. As soon as I get a new operator who won't do as they see fit with my equipment, he'll be given his marching orders. The previous operator yanked on the hand throttle so hard the cable snapped. Took me three days to take it all apart to fit a new one. I just followed the repair guide on prosis. It was a major pain in the ass to do, specially the rubber mat that did not want to come off. You are right, backhoes have a solid frame but don't have any give if someone starts bashing it around. The rock bucket already got dents and that's pissing me off real bad. Thanks for your opinions and advice Spangles
You won't be sorry Cheers
When you post the photos of the broken pin also post one showing where it fits just so that anyone unfamiliar with the machine can get an idea of what it does and the stresses to which it is subjected.
New pin fitted and pics of old broken pin Received pin last evening after breathing fire down the line to the guys at TNT who apparently wanted to schedule the delivery for Monday instead of Saturday after it was cleared by customs late Friday afternoon. Had it fitted in under an hour. I was a bit surprised myself how it was not too hard to do given my poor level of mechanical experience and knowledge. Rubber mallet on the side opposite to the flange inched it out enough for me to remove the part with the flange, slide in the new pin and rubber mallet it into place while it push out the other broken half. Red circle shows where the pin fits on the machine. Pics of broken pin. http://1drv.ms/1NHpVqy As usual, thanks for your advice and opinions Spangles
That pin has failed in what's known as high-cycle fatigue. It's been subjected to a single load that exceeded the capacity of the pin that created a minor fracture inside the pin. After that normal operating loads will be enough to make the fracture grow to a point where the pin fails. The point inside the red circle is where the failure started and is known as a ratchet mark. The concentric marks going out from the fracture initiation point are known as beach marks and you can see how they spread outwards like rings on a tree until the final sudden failure which is the rougher-looking area at the top of the pin in the photo. This pin has been failing for a long time judging by how fine the beach marks are. You'll note that the ratchet mark is actually underneath the case-hardened layer on the outside surface of the pin. How long have you had this machine..? If the answer is not long then there is a chance that this pin was already failing before you bought it.
I've bought the machine two years ago. It was manufactured in 2003 and has clocked 6673 hours so far. Well I can't thank you enough for this more than concise explanation. I've learned something new and very interesting today. Hmm should I start to worry about other pins failing in the near future and make my list of pins to be ordered before it happens or is it something that's not common? Thank you Nige. You are a scholar and a gentleman. Spangles
I'm not seeing any bubbles. Must be talking about the grease hole. Maybe replace it with a solid pin and move the grease hole on the rod end. Nige pretty much summed it all up. Fatigue can take a long time or it can happen rather quickly. Depends on the operator and how much abuse he puts on the machine. Would be a good idea to have a couple spares on hand. Mostly because of down time from shipping and getting it cleared by customs. Looks like most of the pins are the same size and a longer one will fit where a short one goes. It's any ones guess which one could be next. Just realized this is my 100th post! :woohoo
TBH I don't really know if the failure could have started as much as 2 years ago, but I suppose it is possible. As the ratchet mark is right next to the grease hole maybe the failure was initiated by a defect in the drilling of the hole if the drill bit made some kind of mark as it passed through that spot..? However you are right that you need to have your operator change his technique and not beat the bucket on the ground, especially not a bucket as wide as your photo. That will stress all the pins. As whether it's likely to happen to other pins, toss a coin. Because the failure went right through the grease hole I would be tempted to say it was a one-off failure but you wouldn't find me putting too much money on that if I had to.
Agree about the banging of bucket. It always bothered me when a loader operator would sit there banging the bucket on the ground, this was in a stone quarry so "ground" solid limestone!, to try to knock out mud or frozen material. Then they would wonder why cab would rattle from things coming loose.
The pin is induction hardened and its a possibility a copper plug wasn't put in the lube hole before hardening. Possibility only. I see a lot of pins broken through grease holes. If its consistently the same pin I have often had a new pin made with no lubes holes and put a grease fitting in another another spot.
Hello Nige Operator has been changed and now there's one who's much more sensible with the BL71. I guess making a stock of all the pins that could go wrong is a sensible thing to do so as to reduce downtime. No more bucket banging now Kshansen. Client been told to get a roller to compact the rocks cause no bucket banging will be done. He was not too pleased but I'm not going to take any more risks. As usual, thanks for your advice and opinions Spangles
I'm no expert but good compaction does NOT come from banging the bucket against the rocks anyway.