shifting a 15

Last one I drove was in a short hood slope nose Pete, behind a C13 Cat in an oilfield vac truck. It was exactly that, a 10 speed with a low 5. Maybe I had a fussy one, but it didn't much like being shifted from the reduction gear 5th to regular low range 1st or 2nd.

I could have been doing it wrong, but I drove it like a 10 on pavement or faster dirt roads, and used the reduction on steep or tight lease roads and well pads.

 

Shifted like a 10 speed with 5 low gears drove one back in 95 pulling walking floors

 

Now you got me thinking mine was an od think my high gear was up against the dash

 

Ok Guys here ya go, The 15 speed transmission was designed for trucks working in coal country(Appalachian Mountains), where it is not unusual to be grossing 100,000-120,000lbs. The bottom 5 gears are used only when climbing the side of a cliff, so just leave the blue button alone, and pretend like you do not even have those 5 gears. So with the blue button forward, the range selector down, and the shifter all the way to the left and back I'm gonna call that 1st gear. Shift 1-5 split(front button up)then repeat same pattern. If you have a 15 OD then 4th and 5th(low range) and 9th and 10th(high range) are just the opposite 5th is against the dash, and 10th is against the dash. I pulled a 42' frame less dump for several years, and loaded in many coal mines, and I very seldom needed to use deep reduction. Dump bucket guys usually get paid by the ton, so you can imagine if I had a run that went through the woods what I would Gross. Also the 15 comes with overdrive(against the dash) and Non overdrive(regular shift towards the sleeper) I have found the 15 OD to be one of the most versatile transmission out there.

 

The RTO15 speeds are against the dash and a .80 final ratio. The RTLO 15 can have a x plate and have the standard pattern but a .73 final ratio. Both are offered with a direct final ratio as well. The overdrive models were a little tall it seemed to me to start a load without the deep box if you had high gears out back. On them I always start in like third deep to get rolling then split out of deep and go right back into the same hole and just run it out from there.

With the direct trans and 3.70 or lower a 10 speed pattern is about all you need. There are so many different combinations its hard to say this or that is right for every application. I have been told as well the older 15 speeds with the deep reduction button on the dash or in the floor were not designed to be split moving.

 

Old timer here. Drove many 15's. Deep reduction is used for off-road applications and H.H. Otherwise it's a 10 sp. If your going to use the DR side 5 it's only for upshifting not downshifting between Ranges. So if your going up through the DR side you can Range select to the low side but skip 1st and hit 4nd @ the 250 split or DC to 5th @ the 500 split. There ya go.

 

I drove 8LL's and 15's for years. For tandem work just drive it like a ten speed. Use deep reduction for backing so the piston doesn't seize from lack of use. If you need to use deep reduction meaning grossing over 100000 lbs . I used to start off in 2nd deep skip to 5th deep go out of deep reduction and back into 5th low range. That was a smooth quick shift. In soft soil I wouldn't go to neutral coming out of deep and it split just like an 18. Shift the 8 LL the same way. I missed my 15 for years after getting an 18. Always found a 15 shifted faster and smoother. Always joked that on a well used 15 you just had to throw toward the gear you wanted and it would fall in.