Talk:ZF 5HP transmission
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Really Simpson gears in 5HP24 and '30?
[edit]Yes, there's two planetary sets sharing a single sun gear on these models, but the rest of the gear arrangement is very different from the classic 3-speed Simpson gearset transmissions such as the TH400, 727, C6, etc. and their 4-speed variants that add an overdrive unit to them. Notably, 1st gear on the 5HP24/30 uses only the rearmost planetary and is driven through the sun gear, while on the other aforementioned Simpson gearset transmissions, 1st drives through the ring gear, the sun gear rotates backwards, and this is then inverted again through the other planetary gear to the output ring gear. 2nd on Simpson holds the sun gear and the first planetary carrier becomes the output, while the 5HP24/30's 2nd gear compounds using the middle planetary to rotate the rear's ring gear a little faster, whereas in 1st it was held stationary.
Thus it seems to me that the 5HP24/30's gear arrangement is closer to the "progressive compounding" (not sure how else to describe it) planetaries used on e.g. Allison 1000/2000 series. What's the source for the 5HP24/30 being described as having Simpson gears?