hwp
Platinum Member
For those of us who live in the the snow belt it is time to get the snowblower ready for the winter. Aside from greasing the bearings and driveshaft, oiling the auger drive chain and checking the oil in the gear case, you should also check the impeller and drum for wear. The ideal clearance between the impeller and drum is about 0.020" between BDC and the point of discharge a quarter turn later. The clearance between the blade tips and the drum for the other 3/4 turn doesn't matter. It is also a good idea to check the bearings on the impeller drive shaft for wear as any wear in the bearings will cause a wobble in the impeller and vibration.
Over time the tips of the impeller blades will wear and the surface of the drum may become distorted from stones and other debris. A quick test is to lay a dime on the bottom of the drum. On a machine in good shape each impeller blade will pick up the dime anywhere across the face of the impeller blade and carry it to the point of discharge. If one or more of the blades won't pick up a dime, the blades are starting to wear. Now repeat with a quarter. If any of the blades won't pick up a quarter anywhere across the tip, it is time for some refurbishing.
If the drum wall is in good shape, a bead of weld across the tip of the impeller blades will rebuild the worn tip. The tips will then need to be ground to give the desired clearance (0.020") from the drum. If the drum wall is damaged, a sleeve of 1/8" steel can be rolled and welded to the inside of the drum. Of course, the blades will have to be ground to fit the new drum diameter. Now your snowblower is ready for another season. It is amazing how a small change in the gap between the impeller blades and the drum affects the performance of a snowblower.
The other factor affecting snowblower performance is discharge velocity which should be at least 5000 feet per min. To determine discharge velocity, multiply the impeller velocity in rpm by the drum diameter in feet and multiply this by pi (3.14). For example, I run my tractor engine at 2000 rpm, and with the pto in low range, I have a shaft (impeller) speed of 1000 rpm. The impeller in my snowblower is 21" in diameter which gives a discharge speed of about 5500 feet/min - this will blow dry snow about 100 feet.
Happy snowblowing.
Over time the tips of the impeller blades will wear and the surface of the drum may become distorted from stones and other debris. A quick test is to lay a dime on the bottom of the drum. On a machine in good shape each impeller blade will pick up the dime anywhere across the face of the impeller blade and carry it to the point of discharge. If one or more of the blades won't pick up a dime, the blades are starting to wear. Now repeat with a quarter. If any of the blades won't pick up a quarter anywhere across the tip, it is time for some refurbishing.
If the drum wall is in good shape, a bead of weld across the tip of the impeller blades will rebuild the worn tip. The tips will then need to be ground to give the desired clearance (0.020") from the drum. If the drum wall is damaged, a sleeve of 1/8" steel can be rolled and welded to the inside of the drum. Of course, the blades will have to be ground to fit the new drum diameter. Now your snowblower is ready for another season. It is amazing how a small change in the gap between the impeller blades and the drum affects the performance of a snowblower.
The other factor affecting snowblower performance is discharge velocity which should be at least 5000 feet per min. To determine discharge velocity, multiply the impeller velocity in rpm by the drum diameter in feet and multiply this by pi (3.14). For example, I run my tractor engine at 2000 rpm, and with the pto in low range, I have a shaft (impeller) speed of 1000 rpm. The impeller in my snowblower is 21" in diameter which gives a discharge speed of about 5500 feet/min - this will blow dry snow about 100 feet.
Happy snowblowing.
