Quote:
Originally Posted by dle
AHHHHHH :shock:
at the school I went to they called it the 8 speed.
or is there actually a 8 speed transmission?
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A traditional 9 speed is more of an "8 speed plus low". Nearly all 9 speeds follow that pattern, however Eaton at one time made an R ratio "performance 9 speed" that was a true 9 speed, you repeated 4 gears for the first 8 speeds and had a 9th gear that only worked in high range which was overdrive.
Here's the pattern:
R/R 3/4 7/8
1/2 5/6 9
There are 8 speed transmissions which are like traditional 9 speeds without the low hole, just 4 forward positions with range change and reverse. Those kind of 8 speeds are popular in medium duty European trucks and buses. Scania, for example, offers both an 8 speed and an 8 + 1 that is like our traditional 9 speed. ZF offers an 8 speed that is based on a non-repeating pattern, meaning it has 8 positions plus reverse.
R 1 2 3 4
- 5 6 7 8
The ZF box is popular with bus manufacturers.
Dual range 8 speed transmissions are available in the US as well but you don't see them very often. Most fleets just went with a single pattern 7 speed if they didn't need the coverage of a 9 or 10 speed.