cast alum vs cast iron

[fluffyone]

Which is best for tranmissions and rear ends? Cast Alum or Cast Iron? /forums/images/graemlins/confused.gif

 

[Bob_Skurka]

Both or neither depending on the specific alloy used. There are dozens of grades of any metal or metal alloy. On a quality tractor you are typically dealing with a quality alloy. On a cheap tractor you may see a much heavier looking rear end that is actually lower in strength because the alloy is of a lower grade.

Take a look at CUT weights as they come from Japan verses Korea verses China. . . you will see that some of the brands are much heavier than some others, despite the fact that the HP ratings and CLASS sizes are roughly equal. Why? Much of it has to do with metal castings and forgings and the quality of the alloys used. Some brands suggest that because they are heavier that they are better, when the reality is they may be using a lower grade metal so they have to cast it thicker to get similar strength.

 

[rbargeron]

Cast iron and cast aluminum are not vastly different in strength unless you get up into aircraft aluminum or ductile irons, - which nobody uses for tractors anyway. Casting thickness is more a function of foundry techniques than alloy strength.

Whether iron or aluminum is better depends on a lot of design factors. What the machine is, how it is used, whether there is a steel frame too, how many are being made, how much machining has to be done to get it into finished form, etc. etc.

Motorcycles use cast aluminum gearboxes - but many cars use cast iron. Many small garden tractors have die-cast aluminum transaxle housings but almost all larger tractors have iron differentials and either iron or steel axle housings.
There are advantages and disadvantages of each material. Are you looking at a particular situation?

 

[Bob_Skurka]

I should also point out that some manufacturers simply use heavy built castings of high quality. So a heavy cast iron could be better.

I think to really answer your question best, just look at the overall tractor. If you are comparing 2 tractors of comparable overall quality and design, then it should not matter if it is iron or aluminum. If you are comparing a "value" tractor to a "name brand" tractor then you have more to consider than just the metalugy of the rear end.

 

[slowzuki]

Something to note, aluminum has a fatigue life that means it gets weaker the more stress cycles it is subjected too. A good manufacturer includes this in his design so that it would not fail during a normal service life.

I only mention this as it could prove to limit a piece of equipments service life in extreme use (ie commercial TLB use) outside of the original design.

In steel and cast irons you would more likely see stress cracks and things forming from stress cycles.
Ken

 

[fluffyone]

The reason I am asking is (and no one get angry) The Case dealer was showing me some comparisons of the DX to the Kubota. THe DX has a cast iron tranny and front drive axle. THey were also twice the size of the Kubota of the same HP and size. I really like the DX better than the Kubota, but do not want to make a big mistake

thanks /forums/images/graemlins/grin.gif

 

[art]

There is a big difference in the two designs you are referring to. I sell both makes you are comparing. We do far less warrantee work on the Kubota then the NH chassis. The frame is steel on the Kubota vs the cast iron on the NH design. The aluminum housing on the Kubota does nothing other then support the drive train parts as it is not a structural part of the tractor. They in your comparison do not do the same job! The rest of it comes in as the lighter is always better as it allows you to place the correct
weight in it's best place.

 

[slowzuki]

I think the specific kubota model would be valuable to us, sounds like a b7800 or 2910?
Ken

 

[JerryG]

I guess that I am from the old school. If I wasn't going to do anything except mow the yard, the aluminum might be fine. BUT for any real work, the only thing that I would have is cast iron.

 

[sideskraft]

Compared to the competition, Deere uses lots of aluminum and plastic on their E Series tractors, including rear axle/diff and transmission housings. They seem to be priced reasonably in their class, though they are lacking in features and lift capacities. I'm sure they sell lots of them (tons for sale on the used market) and I haven't heard many complaints from owners, considering how many are out there. As large as Deere is, they're not going to release a product that could potentially have reliability issues, especially with all the internet exposure and how websites like this one can affect purchase decisions. Going by sheer mass, Branson seems to have the heaviest compact tractors, with Deere being the lightest, and lots of brands in between (Mahindra, Kubota, LS, Tym, Massey, New Holland, Kioti, etc). For the vast majority of us, buying the "right" tractor comes down to many different factors, such as purchase price, dealer location and attitude/capability, driving comfort, PTO and loader lift capacities, horsepower, anticipated resale value, and even color. In the end it's all about understanding your application and expectations and hopefully finding the tractor that makes you happy.