Hello All,
I am a long time enthusiast of Snowcats and have for a long time been facinated with the workings of the OC12 and other variants. I have studdied it for some time as a hobbie and know (I think) that this system was invented by the Clevland tractor Company (USA) in 1921. It is basicaly a standard all pinion differential augmented by two steering brakes which lock the idler pinions inside the diff. For movement straight ahead the entire diff rotates and the idlers do not rotate relative to the cage. To steer, (i understand) one idler is forced to rotate relative to the cage by applying the appropriate steering brake. This causes one half shaft to rotate slower than the other. My question is: In the straight ahead condition, why doesnt the reaction of the axle torque cause the pinion shafts to spin and therby cause the steering drum to spin backwards. It seems to me that there is still a small enough distance between the center of the internal pinion and the pitch diameter of the compensating (axle driving gear) to cause a reaction. The only thing i can think of is that no matter what the reaction torque on the axle it must be the internal friction of the components and the very small reaction distance between the pinion and compensation gear that keeps this from happening. If anyone wants to discuss it might be interesting at least to me. I wanted to attach a scaned image for reference but I could not figure how to do it.
Thanks,
Scott
I am a long time enthusiast of Snowcats and have for a long time been facinated with the workings of the OC12 and other variants. I have studdied it for some time as a hobbie and know (I think) that this system was invented by the Clevland tractor Company (USA) in 1921. It is basicaly a standard all pinion differential augmented by two steering brakes which lock the idler pinions inside the diff. For movement straight ahead the entire diff rotates and the idlers do not rotate relative to the cage. To steer, (i understand) one idler is forced to rotate relative to the cage by applying the appropriate steering brake. This causes one half shaft to rotate slower than the other. My question is: In the straight ahead condition, why doesnt the reaction of the axle torque cause the pinion shafts to spin and therby cause the steering drum to spin backwards. It seems to me that there is still a small enough distance between the center of the internal pinion and the pitch diameter of the compensating (axle driving gear) to cause a reaction. The only thing i can think of is that no matter what the reaction torque on the axle it must be the internal friction of the components and the very small reaction distance between the pinion and compensation gear that keeps this from happening. If anyone wants to discuss it might be interesting at least to me. I wanted to attach a scaned image for reference but I could not figure how to do it.
Thanks,
Scott