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

Is there any difference between the large frame and pro models as far as in the gear case and in the important places??

The biggest difference between the large frame Simplicity and the Pro models is the chassis.  If you look closely at the Pro models, you'll see that the handles are built with rectangular box frames rather than round tubing.  In additon to that, controls appear to be beefed up.   The descriptions below are a little misleading.  Most of the list of features for the Pro series are also on the large frame machines other than the Power Boost feature. 

Large Frame Dual-Stage Features

• All-Steel chutes rotate left-to-right 200° with minimal effort
• Exclusive ease-of-use features include Easy Turn™ (most models) and Free Hand Control™.
• Easy-Turn™ helps you navigate even the toughest turns with little effort. Simply pulling the trigger on the handle releases the drive power to the left wheel for easy maneuvering and 180° turning. (Available on most models)
• Free Hand™ Control enables the operator to continue operating the snowthrower with one hand while freeing the other hand to rotate the chute, adjust the chute deflector or change speeds.
• Snow Series™ and Snow Series™ MAX engines by Briggs & Stratton are specifically designed to handle tough winter conditions. They offer a primer bulb for quick starts and a large muffler for quiet running performance.

Signature Pro Commercial Duty Dual-Stage Features

• Easy-Turn™ helps you navigate even the toughest turns with little effort. Simply pulling the trigger on the handle releases the drive power to the right wheel for easy maneuvering and 180° turning. Easy-Turn is standard on all large frame two-stage models.
• Power Boost™ is an exclusive Simplicity system that automatically adjusts the power to the auger and impeller as it senses the depth and density of the snow. This enables the operator to maintain optimum performance in the heaviest snow.
• Free Hand™ Control enables the operator to continue operating the snowthrower with one hand while freeing the other hand to rotate the chute, adjust the chute deflector or change speeds.
• Snow Series™ MAX engines by Briggs & Stratton are specifically designed to handle tough winter conditions. They offer a primer bulb for quick starts and a large muffler for quiet running performance.
• Heavy-Duty Cast Iron gear housing along with finely-machined worm gear components deliver top performance in even the harshest conditions.

Pro series also has the electric chute rotation and heated handles -- creature comforts that don't add anything to the function -- but they are kinda fun.

Anyone know how the PowerBoost actually works? I've had one of these for going on two seasons but am not very mechanically inclined. (The few times I've opened it up was with the help of folks in this forum!)

mfduffy wrote:

As much as I like Simplicity machines, I don't like the electric chute control.  Unnecessary gizmology.  Must resist the gizmos.... must resist the gizmos....

Can't tell you how the Power Boost works.  Sound like it's a load sensing system that increases torque as demand increases.   I'm wondering if they use a small clutch system similar to those used in snowmobiles and automatic ATVs?.  

The way they work is that the drive & driven clutches have centrifugal weights and are spring loaded to  adjust the belt at a circumference on the clutch surfaces that matches the torque demand.  At low speeds the belt rides on the inner circumference of the clutches where the mechanical advantage is greater due to the gearing ratio.  A smaller drive gear allows the engine to rev quicker delivering more torque.  As the load decreases and the engine revs up, the clutch weights force the sides of the clutch together which in turn forces the drive belt out to larger circumferences on the drive and driven clutches.  This allows for closer equalization of gear ratios and delivery of horse power at higher speeds.  When the machine encounters more resistance (load), the clutches automatically adjust themselves to deliver more torque.  I'm not saying that's this is the same system used on the Pro series but it would certainly be simple enough to incorporate into a snow thrower.