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Are you talking about starting off in "deep" then shifting to low without stopping? On the 15 speeds I have had most any gear would work depending on the terrain. But I preffered 4th deep coming out to 3 low seemed to work for me. Maybe I am misunderstanding the question

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Remember if it's got a hood it's no good!

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I've only used that gear on a 9 speed. The ratio was close to 5th and came in handy because it eliminated the need to drop into low and go "right and down", epsecially when turning.

I'm just lazy, I reckon.

Jim

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I've only used that gear on a 9 speed. The ratio was close to 5th and came in handy because it eliminated the need to drop into low and go "right and down", epsecially when turning.

I'm just lazy, I reckon.

That's me, i've only heard of "cheater gear" in 9 and 13 speeds,only tried it a time or two.

Producer of poorly photo-chopped pictures since 1999.

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8LL has it to. It's where lo is on the "low"side just on the high side. Same as the 9 and 13.

It works but really feels like it shouldn't be in there.

I can't believe there are u tube videos calling it the hidden gear.

I only drove a dump truck with an 8LL, hauling dirt at the shop when we had to biggerize the driveway. That was for about half a day, and about a 300 yard haul. I never drove a 15 speed deep reduction.

Producer of poorly photo-chopped pictures since 1999.

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I'm still trying to figure out an extra gear on a 15-speed. Don't know where that would be. I'm like everyone else, familiar with "nothing" & "double-nothing" on a 13-speed. But my 15-speed doesn't have any unused gears...

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"Eagles may soar, but weasels don't get sucked into jet engines."

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Exactly!!!

They really should have called them "12-speeds", shouldn't they?!

Mine is the RTF-915. Direct in high gear. Normal shift pattern.

If you swap the gearsets in the box to make it an overdrive in high (see pic), every gear (except "direct") gets raised one notch, so the 4th and 5th positions would be reversed. If you didn't like that pattern, Fuller offers a shift plate (basically the top of the trans) which reverses the 4th and 5th shifter fork movement. This would put the pattern back to "normal". There's where all the "x-pattern" and "h-pattern" business comes from.

The older boxes, incidentally, should have an "O" in the number to indicate overdrive...like RTO-915. I can't tell you a blasted thing about the newer stuff.

My RTF-915 would be Roadranger, Transmission, Front-shift-tower, 950 ft-lbs torque rating, 15 speeds. Elegant system, isn't it? Just wish it was an RTFO-915, with the X-pattern body... Maybe if I ever pull it out, I'll change it!

post-11199-0-90638400-1408362578_thumb.j

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"Eagles may soar, but weasels don't get sucked into jet engines."

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Yes you can change from direct to over drive by swapping the gears around and I have did a lot of them in years past but when you do you will dislike it. It will have a coming home gear when in hi. There is too much of a split between the two gears.A factory o/d has all different gears in it and you end up with a smaller split from the factory set up.But in the early years we upgraded HP at over haul time and then next thing was add some speed.I never saw a man that was happy with swapping the gears.I never did try to figure the o/d ratio but its big.

glenn akers

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BINGO...!! We have a winner..! My Superdog has an RTX15715 (X denotes std. shift pattern, single OD). When shaking a heavy load, I run thru all 5 stick positions in "deep", then shift back up to the 4th stick position simultaneously flipping the deep button which gets it ready for two gears in the low side of the range selector. Then shift the range selector to high for the remaining 5 gears. This yields a total of 12 perfectly spaced ratios with no duplicates. This method will gain the most ground speed before an air shift takes place.

Used to do the same thing on my RD with a 8LL. My brother was brutal (on his truck) . Showed him how to do it, he said "Oh", but he would rather slip the clutch like riding a two stroke MX bike than use deep, think the blue button scared him. One reason I never let him drive mine.

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Used to do the same thing on my RD with a 8LL. My brother was brutal (on his truck) . Showed him how to do it, he said "Oh", but he would rather slip the clutch like riding a two stroke MX bike than use deep, think the blue button scared him. One reason I never let him drive mine.

I could never figure out what was so hard about flipping that button. Guys never do it with 8lls.

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Matt

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When i went to look at the brockway the previous owner told me it was a nine speed. When i was looking underneath i saw the trans and knew it wasn't a nine speed because of the extra section on the back. I thought it looked like a fifteen speed but the id tag was long gone. Then i found the deep reduction switch next to seat ( it was safety wired in out position). When i asked the guy about it he said " I never used it it was too slow". What is strange about this trans is you don't use the first gear position in the high side. It does act like a nine speed instead of a ten speed like any fifteen speed i remember driving. So what is it?

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Yes you can change from direct to over drive by swapping the gears around and I have did a lot of them in years past but when you do you will dislike it. It will have a coming home gear when in hi. There is too much of a split between the two gears.A factory o/d has all different gears in it and you end up with a smaller split from the factory set up.But in the early years we upgraded HP at over haul time and then next thing was add some speed.I never saw a man that was happy with swapping the gears.I never did try to figure the o/d ratio but its big.

According to the Fuller service manual...

15-speed direct

Deep Reduction

R - 13.03:1

1 - 12.0:1

2 - 9.42:1

3 - 7.45:1

4 - 5.90:1

5 - 4.78:1

Low Range

R - 8.73:1

1 - 8.05:1

2 - 6.30:1 (22%)

3 - 4.99:1 (21%)

4 - 3.95:1 (21%)

5 - 3.20:1 (19%)

High Range

R - 2.73:1

6 - 2.51:1 (22%)

7 - 1.97:1 (22%)

8 - 1.56:1 (21%)

9 - 1.24:1 (21%)

10 - 1.00:1 (19%)

15-speed overdrive

Deep Reduction

R - 10.55:1

1 - 9.73:1

2 - 7.62:1

3 - 6.03:1

4 - 4.78:1

5 - 3.87:1

Low Range

R - 7.06:1

1 - 6.51:1

2 - 5.10:1 (22%)

3 - 4.07:1 (20%)

4 - 3.20:1 (21%)

5 - 2.59:1 (19%)

High Range

R - 2.21:1

6 - 2.04:1 (21%)

7 - 1.59:1 (22%)

8 - 1.26:1 (21%)

9 - 1.00:1 (21%)

10 - 0.81:1 (19%)

Swapping the drive gears changes the speed of the countershafts. The spacing between gears is determined by the relative number of teeth on the various gear sets.

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"Eagles may soar, but weasels don't get sucked into jet engines."

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Exactly!!!

They really should have called them "12-speeds", shouldn't they?!

Mine is the RTF-915. Direct in high gear. Normal shift pattern.

If you swap the gearsets in the box to make it an overdrive in high (see pic), every gear (except "direct") gets raised one notch, so the 4th and 5th positions would be reversed. If you didn't like that pattern, Fuller offers a shift plate (basically the top of the trans) which reverses the 4th and 5th shifter fork movement. This would put the pattern back to "normal". There's where all the "x-pattern" and "h-pattern" business comes from.

The older boxes, incidentally, should have an "O" in the number to indicate overdrive...like RTO-915. I can't tell you a blasted thing about the newer stuff.

My RTF-915 would be Roadranger, Transmission, Front-shift-tower, 950 ft-lbs torque rating, 15 speeds. Elegant system, isn't it? Just wish it was an RTFO-915, with the X-pattern body... Maybe if I ever pull it out, I'll change it!

Sorry...

the "T" is for "twin countershaft". Stepped out for a moment there...

"Eagles may soar, but weasels don't get sucked into jet engines."

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I could never figure out what was so hard about flipping that button. Guys never do it with 8lls.

Had a guy when we had dumps that would not touch it for any reason. Think he was scared or tearing up driveline. I do not know why and he is in the fed pen. Damn truck was a beast. Slower then hell but would go everywhere. 270 Cat 8LL with 5.29's in the back

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