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

Intake shoot question.

I’ve noticed that on some snowblowers the bottom of the intake shoot swoops under the augers and about even with the forward edge of the augers. On other machines the bottom of the intake shoot is in back of the center of the augers.

The forward edge machine requires that the augers be higher, about an inch or inch and half above the scraper bar.
For the machine with the scraper bar in back the augers were lower.

It seems the forward scraper would be clearing to the ground by scraping with the scraper bar. The lower auger unit would be clearing to the ground by the augers.
What’s the difference in design for? Would these designs have a difference on gravel and tar driveways?
David

You may be thinking of single-stage design versus two-stage design. Only on single-stage machines does the auger contact the ground, in fact that's how single-stage machines propel themselves. For this purpose they have rubberized auger blades and their chute intake is set much more forward than on two-stage machines. On two-stage snowblowers the impeller, which is absent on single-stage units, sucks air (and snow) towards the back of its 'throat' for the impeller to discharge it through the chute. On a two-stage machine propulsion is provided by the blower's wheels or tracks and the role of the auger consists mostly of crushing and feeding the impeller with snow scooped up  by the scraper that is already present in the bucket.  Single-stage designs do not work well on uneven surfaces so their use is pretty much restricted to pavement  or even hardened snow while two-stage machines can work on a wide range of  surface conditions.

I saw an MTD 10hp two stage on which the bottom part of the intake/auger housing ran under and forward of the augers. That put the leading edge of the scraper forward and under the augers.
I never paid much attention to where to that before. I looked at Ariens and Toro machines and the scraper is behind the augers.

With the MTD the augers cannot get as close to the ground but the leading edge of the scraper is probably breaking and lifting snow feeding the augers. With the edge in back the augers can be lower although not touching the ground but close so breaking up the snow.
It was not clear to me which would have the advantage. The forward scraper might perform better on rough and non-paved driveways and also protect the augers but that’s just a guess.

What is best on gravel and other rough surfaces is simply more clearance between scraper and ground, drop the skids a bit. What we want is to avoid the jerking and picking up of dirt and rocks that occurs when the scraper is being involuntarily used as a grader so we have no choice but to leave a film layer of snow on the ground at least until the soil freezes hard. I can't imagine a forward scoop would be of any further help on this type of surface, quite opposite considering that the skids would have to be lowered even further than they would with a more standard rear scrape. The way you describe the MTD reminds me of the design that was prevalent in the 1970's and was based on the "scoop effect" as opposed to later designs which favored a scraper effect. The idea with the scoop design was to raise the snow level inside the bucket towards the front of the auger blades, which gave a better finish since it left no 'contrails' on the ground as most current blowers do, as long as the operator was careful not to speed, so to speak. This gave good results on low to moderate amounts of snow when the surface was smooth but was notoriously awkward on gravel. Scraper blowers have a somewhat rougher finish but are much more versatile which is probably the reason why most machines built nowadays adopt this approach.