I spend a lot of time with these machines, with all that time comes things you find that make you curious as to why something is made the way it is. The bucket linkage/dog bone, the piece that goes from the bucket cylinder to the bucket/coupler. WHY ARE THERE TWO PINS ON THE ONE END? Why why why? Why can't they just build it like any other darned linkage, NO!!!! This one has to have 3 pins, the two top ones are a P.I.A. to grease. I can't get a picture of the linkage but anyone that has been around one knows what it looks like.
I believe it is to give the bucket more range of motion, specifically to curl in farther. If I recall on the one I ran a few years ago, it curled in really far but didn't uncurl as far as a normal excavator.
They don't curl out as far, you're correct. It just don't make sense to me from an engineering stand point. I've questioned the Cat "product specialists" to the point that they get sick of my crap and tell me I should go design the equipment myself. One salesman told me that this is how they design them in Europe so it's how they make them. I've run all kinds of excavators, on tracks and tires, and the M family of Cats is the only that uses this type of linkage.
Well the rubber tired hoes, I.e. m series don't work on benches so they wouldn't need to un curl as far. Unloading or loading a truck on the same level it's more useful if the bucket curls in farther to hold the material so it doesn't spill. Could be their reasoning. Most guys at dealerships are morons and don't know anything about how the equipment is used in real life. One thing I do know is the m hoes can put gradalls to same with the right operator in the seat.