NAA Hi-Lo transmission

petertay

Member
My 1954 NAA has a 4-speed tranny, but it also has a hi-lo lever on the right hand side, so it has eight forward speeds. While in Lo, 1st gear is not what I would call granny-speed, it moves along at a fast walk. In 4th gear, it goes as fast as feels safe on the highway.

Since 4th gear (in Lo) is that fast, I've not even tried the Hi speeds.

What would such a transmission be used for?
 
Your high-low gearbox is commonly called a Sherman transmission, and is 3 speed, not 2. It has high-direct-low speeds. This gives you 12 forward and 3 reverse speeds. More gear ratios are always better than fewer - it makes your rig much more flexible.

If your tractor was "scary fast" in 4th gear, you likely had it in high range. Here's more info: http://www.oldfordtractors.com/sherman.htm
 
So do you have the lever up or down. Or have you tried to go to neutral on the Sherman which is is called the pull the lever out sideways. If it will come out about a 1/2 inch side ways you have a combo and when side ways and up it i in the standard gears which is what it would have with out the aux transmission. When pushed in up is high down is low and as I said out an up standard gears
 
Bern posted the best [b:7bf08613e5]link[/b:7bf08613e5] I know of for information.
If the handle is on the right hand side sitting on the tractor, I
don't believe that would be Sherman though. Maybe a Hupp?
Can you post a picture of it?
 
Your high-low gearbox is commonly called a Sherman transmission, and is 3 speed, not 2. It has high-direct-low speeds. This gives you 12 forward and 3 reverse speeds.

There were a few different Sherman Auxiliary transmissions made in addition to the step-up/step-down combo. There was also a plain step-up, a plain step-down and a reverser. But the handles on the Sherman's were always on the left as far as I am aware, except for the ones with the cable shifter.
 
This shows the right side and top. Note the long lever with Hi-Lo painted on the side. Power steering was also added to this NAA. Next I have to take that apart to eliminate an oil leak.

38961.jpg
38962.jpg
 
used for? different ground speeds.

if you were going to the market you wanted faster.

if you were pulling something that needed slow ground speed, but didn't need the pto, your low/1st and throttle could get you
down to barely moving at idle..
 
Pics Thx to John Smith
Petertay,Looks like you have a Hupp Dual Drive aux transmission.Low is shifted from neutral,pull shifter out then shift forward.
huppshift.jpg

huppad.jpg
 
Yup, it's a Hupp. I didn't know that the lever has in-out as well as up-down positions. I'll have it running agian in a few days and can't wait to try out the extra gears. Does it shift on the fly, or from standstill?

This is my 4th old Ford (8N, Select-O-Speed, 861, and now this NAA), but was unaware of these add-ons.

Thanks YT and you helpful guys.
 
"Does it shift on the fly, or from standstill?"

Stand still.
Other than your SOS, none of those were meant to be shifted while moving.
 

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