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

I was reading about the Clarence impeller improvement online today. It attaches a rubber gasket to each impeller blade ceiling it against impeller housing. Most who tried it seemed to report outstanding results especially with heavy wet snow. The only place where some reported it may not be effective were on units, such as the Honda, that reportedly have very tight clearances tween the impeller blades and the housing from the factory.

Ariens snowblowers are well-known for their high-capacity high capacity. Well most large snowblowers at 12 inch diameter impellers, the Ariens have 14 inch. That is over 16% faster speed at the end of the impeller blade. Does that give them a decisive edge?

So the question is: how important is the design of the impeller to the overall system performance? Are tight clearances between the impeller and it's housing critical? If so, which brands have the tightest ones? Is the diameter of the impeller critical? If so, did he Ariens and others with large impellers have a distinct advantage? The Clarence kit is inexpensive if you can install it yourself. Should everybody be installing these kits? TheToro has a unique impeller housing. Partially plastic, it has a return for excess snow to be returned to scoop. The effective Toro and edge or is it a disadvantage?

Toro: http://www.youtube.com/watch?v=ZTAAaT_sFss

trouts2 wrote:

The Ariens also has a 14" impeller, so at 1300 rpm that would be 4750fpm and if the Subaru is 10% faster it would be 5300fp@4000rpm. What is the Honda? MTD has a 16" impeller in some Club Cadet and Sears models.

The impeller issue is that snow removal has three qualities: how long does it take, how much effort it takes, and how good a job it does. The impeller is part of the first goal, as is scoop size and auger performance. Steering, is part of the second. Throw and scrapper technology part of the third. Adjusting the scoop can be part of all three.

The Honda 'advantage' may be the hydrostatic drive. Whey are a single unit that internally have a variable flow pump and a fixed flow motor. A lever adjusts a cam on the pump changing its output voume per input revolution. Excess flow uis bypassed internally. On friction disc models slippage is possible but unintentional. In both the impeller is run off  a fixed reduction from the engine. As a result, in a hydrostatic drive changes in resistance shouldn't affect impeller speed, but in a friction disc they may. The hydrostatic drive may also allow a greater reduction in speed, The slow movement of the Hondas may be part of their strength; reviewers praise them, usually tracked, for getting through big EDD piles or plowing up hills. Both could be the result of the slow movement speed and constant impeller speed.

Note: Husqvarna has a 30" hydrostatic drive model. However, the auguer and impeller are both 12". It has left/right free wheel 'power steering' and the B&S 342cc Max engine.

trouts2 wrote:

The Ariens also has a 14" impeller, so at 1300 rpm that would be 4750fpm and if the Subaru is 10% faster it would be 5300fp@4000rpm. What is the Honda? MTD has a 16" impeller in some Club Cadet and Sears models.

The impeller issue is that snow removal has three qualities: how long does it take, how much effort it takes, and how good a job it does. The impeller is part of the first goal, as is scoop size and auger performance. Steering, is part of the second. Throw and scrapper technology part of the third. Adjusting the scoop can be part of all three.

Total mass or mass/volume movement is the limiting factor in speed. The Honda may be clearing, but is it clearing fast? When the snow is lighter, the wider scoops would also make it faster, as then the impeller isn't the limiting factor.

The Honda 'advantage' may be the hydrostatic drive. Whey are a single unit that internally have a variable flow pump and a fixed flow motor. A lever adjusts a cam on the pump changing its output voume per input revolution. Excess flow uis bypassed internally. On friction disc models slippage is possible but unintentional. In both the impeller is run off  a fixed reduction from the engine. As a result, in a hydrostatic drive changes in resistance shouldn't affect impeller speed, but in a friction disc they may. The hydrostatic drive may also allow a greater reduction in speed, The slow movement of the Hondas may be part of their strength; reviewers praise them, usually tracked, for getting through big EDD piles or plowing up hills. Both could be the result of the slow movement speed and constant impeller speed.

Note: Husqvarna has a 30" hydrostatic drive model. However, the auguer and impeller are both 12". It has left/right free wheel 'power steering' and the B&S 342cc Max engine.

We measured the John Deere today using a 480frame/sec exposure. It is nearly exactly 20 rev/sec, 1200 rpm.

DavidNJ wrote:

Who's we?

Wife and me. Did you think it was a CIA operation? Or in a ME laboratory in the basement of building 2 at MIT?

DavidNJ wrote:

It takes two people at MIT to determine the rotational speed of a snowblower impeller? On a Saturday? My first thought would be "union workers" on double pay each. Interesting couple you two are.

Would never have thought it was anywhere at MIT. Once a great school, now it's just an acronym for Morons In Training.

aa335 wrote:

Yea, that happens to lots of schools with 2300+ board scores for admissions.

Wouldn't it be easy just to take the engine rpm and the ratio of the pulleys off the crank and impeller then do the math? Friiy

friiy wrote:

Depends if you're a mathematician, an engineer, or a handy man.

Depends on whether you can get to the pulley or not. A strobe light, timing light would be easier. Non invasive, just takes at most two people. One to fiddle with the strobe light, the other to hold down the lever thing to get the auger to turn. Or just use duct tape, and lose the second person.

However it's done, a 50 page thesis on it isn't necessary.

For Airens you can just count the auger rotations for a few seconds like taking your pulse.  A chalk mark or piece of tape on the blade helps.  That # times 10 gets the impeller speed.  For other most other US machines the impeller is 10 times the auger RPM.

I think Yamaha and Honda may have a higher ratio.  A Yamaha 6hp runs at 4000 RPM and will keep up with any US 8hp in distance and throughput.  As a note the Yamaha at lest has 4 roller bearings in the gearbox and the auger shaft supported by roller bearings.