The Forestry Forum

I am in desperate need of crankshaft bearings for my 051 av.  All the ones I come across are grooved ball bearings.  Only problem is my saws have roller bearings on one side ball bearing the other side.  Does anyone know where I can find these.

Looking up in my IPLs, the 051 had 20x47x14 grooved ball bearing on the power take off side and 17x40x12 grooved ball bearing on the recoil side.

Roller bearings in a small engine would not be first choice for three reasons. Most of these bearings are not captured: either the inner race or outer race are separate from the rest of the bearing assembly.  The 051 used snaprings into the the cases to hold the bearings in place. This worked fine for a grooved ball bearing where both races are captured. But with a roller bearing this snapring would just hold the outer race. This would allow the inner race to be free to move inward or outward on the crankshaft. With engine running roller bearing may disassemble itself.

Second reason is that roller bearings need more lubrication for the larger/longer bearing-to-race contact than lubrication needed for ball bearing contact.

The last reason may be less problematic in small engines: cylindrical roller bearings don't allow for crankshaft flex, barrel-shaped or spherical roller bearings were developed to allow for this flex (see Norton motorcycle history).

Anyway, Swedish SKF does make cylindical roller bearings. Chinese FAG makes barrel roller bearings. Try eB*y, just saw some there now.