Hi guys,
I'm trying to reverse engineer a planetary gear design because of urgent needs for getting the spares part (the planet gears had worn out) and supplier is quoting a 10 weeks lead time.
The existing design is as such - 11T Sun Gear, 12T Planet Gear and 37T Ring Gear.
Based on measurement of the 12T planet gear (18.03mm OD), I reckon it is a DP20 gear which might be profile shifted (which it should be, otherwise there would be issue with these gears meshing based on these numbers of teeth). The PCD of the planet gears is approximately at 31mm (I can't get an accurate measurement because of the 3 planet design).
My issue is with the gear dimensional calculation. I'm referring to the SDP/SI document where there are isolated calculations for an external-external gear pairing and for an external-internal gear pairing. I can't get the numbers (tip, working pitch, root diameters, center distance, etc.) to match between these two set of calculation for the same planet gear. And I realize that the numbers only match when I change the Ring Gear to 35T. However, as it is an existing design, I have to keep the teeth numbers unchanged.
Have anyone encountered such situation before and how should I tackle this? Or would it be acceptable to try fabricating a DP20 12T profile shift x=0.1 and specify a tip diameter of 18.03mm and hope it fits. Thanks!
I'm trying to reverse engineer a planetary gear design because of urgent needs for getting the spares part (the planet gears had worn out) and supplier is quoting a 10 weeks lead time.
The existing design is as such - 11T Sun Gear, 12T Planet Gear and 37T Ring Gear.
Based on measurement of the 12T planet gear (18.03mm OD), I reckon it is a DP20 gear which might be profile shifted (which it should be, otherwise there would be issue with these gears meshing based on these numbers of teeth). The PCD of the planet gears is approximately at 31mm (I can't get an accurate measurement because of the 3 planet design).
My issue is with the gear dimensional calculation. I'm referring to the SDP/SI document where there are isolated calculations for an external-external gear pairing and for an external-internal gear pairing. I can't get the numbers (tip, working pitch, root diameters, center distance, etc.) to match between these two set of calculation for the same planet gear. And I realize that the numbers only match when I change the Ring Gear to 35T. However, as it is an existing design, I have to keep the teeth numbers unchanged.
Have anyone encountered such situation before and how should I tackle this? Or would it be acceptable to try fabricating a DP20 12T profile shift x=0.1 and specify a tip diameter of 18.03mm and hope it fits. Thanks!