HD 41-(FD50) & D 11 working

D11 at 850 HP and Fiat Alis FD50 (HD 41) Pushing overburden

Edited by Coke-in-MN - 29 Apr 2011 at 11:30am

I have been told that when they became the FD50 there was a change in the final drive planetaries that made a great deal of difference in the failure rate, there was just too much giddy-up for the rest of the tractor. When I was a kid I collected a lot of sales brochures from manufactures, I still have an original brochure for the HD41 from the early 1970's touting 524 hp, I thought that I needed one in the worst way, it scared Caterpillar enough to spawn the D-10 and then the 11. I really never did understand the high track, I know it is supposed to be easier access to the finals and the sprockets are out of the dirt, but the track has to bend 30% more each revolution and seeing the track have to suspend itself from the sprocket to the front idler has to be a wear item on sprockets and pins and bushings. The SALT tracks made a big difference but boy do they "clop clop" especially in the bigger Cats, that can't be the best for things. Cat must have thought it is a winner, but the funny thing, the newest experimental "cats" are back to conventional tracks.

Great video, thanks for sharing

 Who has more fun than people on tractors? Tad

the original D10 became what is now the D11. It looks to me like the FD is moving faster, where the D11 looks to be struggling pushing the load.


Edited by injpumpEd - 01 May 2011 at 6:06pm

Not to be argumentive here, but I have read numerous times where the HD 41 and other AC crawlers were plagued with final drive problems, and after talking to numerous people in the salvge business, and some owners of the big AC dozers that "rumour" of final problems just doesnt seem to hold water. I havent talked to one salvage yard that didnt tell me they sold  more finals to Cats and others as they did to the AC line. I have an HD11B that I bought missing some parts we had to call all over the US to find an HD 11B in salvage, found one in Tenn, and one in Ark that we got some parts off of, so if these dozers were such a bad thing where are all the junk ones?The 41 logged a huge amount of test hours before AC released it into the public, I know first hand of the abuse AC engineers did to destroy an allis made product so I have a hard time to believe that they "missed" a final problem. After asking many mechanics about this so called weak spot they told me 2 things, one was that the finals were getting loose and not maintained propely when they seen one fail, and second thing they told me was the amount of torque and power on a 41 or any AC crawler with a converter on was tremendous compared to the competition, the stall ratios were extremely high in comparison to a cat so the amount of work being done by an AC crawler was extremely more than its rivals, and when taken that into consideration the failures were not many. They also told me that the final failure was more of a rumor started by the competition because they could not make a tractor that large or powerful. Another comment made was that when AC sold some interest off to Fiat , AC didnt do as much of the castings as they did on the original 41's so one some of the Fiat Allis 41s some problems occured, but was remedied by changing the stall ratios on the converters so the amount of torque wasnt as great. I know only a few actual owners of 41's, and they had no problems with the ones they owned and one company had 6, I am trying to buy the remaining one they have left but to date havent reached an agreement. I have to wonder how much validity is in this so called failure problems.