Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

   There is usually some confusion when referencing Ariens made gearboxes.  The terms aluminum and steel are used to differentiate between the two types.  The housings are different but it is what is inside that makes the difference.  If you do not know what is inside you are left wondering why an aluminum case is better than a steel case (case iron). 

   The terms used of steel and aluminum are used to distinguish between the better quality gearbox (steel) versus the lesser quality gearbox (aluminum).  The quality connotation includes the material used in the gearbox but the real meaning mostly refers to the internal components.   Below is a link to exploded views of an aluminum and cast iron gearbox. 

It’s easy to make a very strong gearbox of aluminum as Toro has done.  That is nice but it is what is in the Toro gearbox that makes it a good gearbox.  By the way the Toro aluminum gearbox is much thicker than most other companies gearboxes (MTD, AYP, and all others that I know of).

http://www.kedawei.com/Doc1.doc

I had a look at the two diagrams and many of the part numbers are the same. The thrust bearings are no where to be seen and the aluminium gear case comes with an extra squeeze bottle of loctite. There are differences but they appear to be mostly due to a shorter worm shaft on the iron version. Kind of disappointing.

At the same time I've been using an aluminium gear cased unit for several years at 10-20 times normal usage with no problems.

Paul,

   You’re right the part numbers cross and all the good stuff in the old cast iron gearbox gone.  I knew the new cast iron gearbox was different shape but did not know about the internals changes.  The new worm assemblies are 52419600 cast iron and 52100900 aluminum.  They look the same in the drawings so not sure what differences call for a part number change.

trouts

The worm assembly includes the housing, either aluminium or cast iron so I have a hunch the internals are the same but the part numbers for the assembly are different due to the housing. Don't forget that most diagrams are from CAD systems where cutting and pasting is a way of life.