Snowblower guts

When I was a kid, my family and I were all up in Hooper, NE for a family reunion. Having grown bored with adults pinching our cheeks and telling us how cute we were, my brothers and I escaped to Hooper Memorial Park. I thought I was hot stuff whenI climbed into the middle of the merry-go-round we were on, but I was surprised to find out that the middle was turning slower than the benches along the outside of the ride. I learned an important concept from the land of Physics that day. The relative speed of a rotating object increases the further you travel from its axis.

I was also surprised to learn that this same principle is what makes the drivetrain of our slowblower work. My dad, who now lives in Dallas, has given us custody of his MTD "I-eat-Nebraskan-snow-for-breakfast" two-stage snowblower, since the annual snowfall in Dallas doesn't really necessitate *a* snowblower, let alone one of this magnitude. I guess technically it's a snow thrower, but that doesn't have the same ring to it. The last time I took it out the belt that runs the auger and fan didn't perform very well (as in it jumped the track several times, and then became so shredded that it transferred very little power to the assembly it was supposed to be driving). Since we are expecting up to 8 inches of snow Saturday night, I thought it would be a good idea to repace the worn belt sooner rather than later.

In order to access the belt, I had to take the access panel off of the bottom of the machine. The images you see below are from that perspective, with the snow blower tipped forward on its "face." I like to tinker with things like this, and I am always fascinated to find out how stuff works. Yes, howstuffworks.com is in my favorites list. I thought the drivetrain of the snowblower was so fascinating that I couldn't help but pass my findings on to you.

Image 1 (First Gear):

Image 2 (Fifth Gear):

Image 3 (Reverse, Second Gear):

I took these on my phone, so the resolution isn't perfect, but you get the idea. When you pull the drive lever on the handle it engages a tension pulley, which engages a belt that drives the wheel that you can barely see in the bottom of image 1. This drives the drivewheel that is connected to it (the main horizontal wheel in image one). Perpendicular to this wheel is another wheel that has a rubberized rim on it. This wheel drives a shaft that interfaces with the driveshaft in a small-to-big gear relationship (left side of image one), and this driveshaft is what drives the wheels.

The brass-colored assembly you see attached to the rubberized drive wheel is what sets the speed and direction. By adjusting the "gear" lever, this shuttle changes the rubber wheel's relationship to the faceplate. By changing its distance from the center of the circle, it adjusts the speed of the drivetrain in relationship to the RPM of the faceplate. Image one is first gear, so it is very close to the center, giving low speed relative to RPM. Image 2 is in 5th gear. It is way out toward the edge of the faceplate, giving it a higher relative speed at the same RPM. Image 3 is Reverse 2. By moving the rubberized wheel to the opposite side of the faceplate, it adjusts the direction in which the driveshaft rotates.

The clutch in this drive is the tension pully that engages the belt that drives the main wheel at the bottom of image 1. If it's spinning, everything else is as well. If not, the ruberized wheel can slide back and forth as if it were in neutral. This whole system allows the engine to run at the same speed the whole time, regardless of if the wheels or auger/fan assembly are engaged.

Tune in next time, when I'll explain how a shovel works.