pinion to gear hardness ratio
pinion to gear hardness ratio
(OP)
Hi
Currently I have a system from a vendor with a 1.25:1 ratio. The Gear is 84 Hrb and the pinion is around 42 Hrb (I can't really get to it to test it easily, I'm guessing from a material book). No surprise the pinion is failing very quickly. My question is how much harder do I make the pinion for best performance? I have a book that suggests the pinion should be 20 to 70% harder, that seems like an awfully large range. I assume it should be dependent on the ratio of the drive, since the ratio isn't extreme do I stay on the low side, say 20-30% harder?
Thanks
Currently I have a system from a vendor with a 1.25:1 ratio. The Gear is 84 Hrb and the pinion is around 42 Hrb (I can't really get to it to test it easily, I'm guessing from a material book). No surprise the pinion is failing very quickly. My question is how much harder do I make the pinion for best performance? I have a book that suggests the pinion should be 20 to 70% harder, that seems like an awfully large range. I assume it should be dependent on the ratio of the drive, since the ratio isn't extreme do I stay on the low side, say 20-30% harder?
Thanks





RE: pinion to gear hardness ratio
RE: pinion to gear hardness ratio
The gear is 303 so hardening is out, its a difficult system to explain but I do not want to change anything on the gear. The pinion is some sort of brass/bronze. I want to replace the pinion with something that is a better match to the 303 stainless.
RE: pinion to gear hardness ratio
Can you provide more details?
RE: pinion to gear hardness ratio
RE: pinion to gear hardness ratio
You have not provided enough information about your gear mesh and its operating requirements to establish a satisfactory reply.
CoryPad makes an excellent point. One of the basic principles of good gear design is to equalize the tooth strength, fatigue life, etc. of both gears. This is usually accomplished by careful selection of materials and heat treatments, tooth geometry modifications, adjustments in face widths, lead corrections, etc.
It would be very unusual to intentionally design one gear in a mesh to have a much reduced life versus its mating gear. The only instances where I've seen this done is where there is a possibility of jamming or overload. The one gear is made much weaker, and will hopefully fail without causing damage to its mate, because it is easier and less expensive to replace.
Good luck.
Terry
RE: pinion to gear hardness ratio