Please help. I got gifted a 1966 T855 tandem dump truck. I have no idea how to shift this beast. Has 2 shifters. First one is pretty basic, that second one is very strange to me. On the shift knob, lower left has a "U", lower right has a "D", upper right has an "O". Does anyone know what the who these stand for? Thanks in advance for any help.
A wild guess would be under drive, direct, and overdrive. But I really have no clue
Most likely a main transmission and an auxiliary transmission setup, pretty common of trucks of that era. Main tranny is typically a 4 or 5 speed, 1st gear is typically a granny gear. The hog box, auxiliary, is typically 2, 3 or 4 speed. On yours, U, D, O, that's Underdrive, Direct, and Overdrive.
There are a bunch of ways to drive those old trucks. We had a grain truck with that setup. Best advice I can give is don’t get both boxes in neutral at the same time and keep it simple. You don’t need to run all the main gears through each gear in the aux. With some practice you can go something like this….. Main in low, aux in under to start. Shift a gear or two in the main then shift aux from under to direct, run the rest of the main box to high gear then go overdrive in the aux. Once you’ve done this a few times you’ll start to figure out what gears it likes. You can also use direct and over in the aux to split each gear in the main. Under is generally to get rolling loaded or creep around in the field. Our tandem grain truck would struggle in overdrive with a full load so keep that in mind.
It posted my reply twice for some reason.
I'm going to be the wet blanket on this party. You weren't "gifted" you've been stuck with it. The brakes are worthless on that truck, way too small.
^^^
Thanks. That helps.
Not stuck with it. Only going to be used on my property for a while then selling it. The truck could not be made legal again anyways, has copper air lines. So old school.
Thanks for the input. That really helps.
I would like to see a picture of your truck.
Hope the picture doesn't crack your screen. Oldie but goodie. Both of them.
I had lot's of miles on trucks like that, mostly Fords too. We did lots of work with them back in the day. FWD
Perfect truck for that job I bet it has some deep gears to crawl with
Is it gas or diesel powered?
Lots of gas powered. Has a 534 with a Holley 600 double pumper feeding the monster motor.
Most I've seen had a Cat 1160 diesel engine and a 5 and 4 transmission set up. Still completely gut less but we drove up hills empty and came back down with a load. The only reason the cops ever pulled one of those trucks over was for a missing mud flap.
I am not a truck driver. Still trying to figure out the shifting. It is either a 3 and 3 or a 5 and 3 transmission. It also has a split differential. The dang linkages are missing for the differential and the shifting fork is messed up for the secondary. Using the beast though for some gravel relocation projects on my property.
That is a lot of gears to choose from.
Mean to tell me copper air lines are outlawed on the road.
5 X 3 and two speed drives was a option.
The main box was the five speed. You put the main box in gear and can shift it like any Toyota five speed pickup transmission. There is a catch though, the engine doesn't have enough torque range to pull into the next higher gear so they put the aux box in the will allow you to make small speed changes between the big speed changes in the main box. You might start out in 2 on the main box and 1 in the aux when you have a load. You can't make to 3 in the main so you shift to 3 in the aux and then 4 in the aux. Now you can shift to 3 in the main but you have to shift back to 1 in the aux and continue like that up to your desired speed. We called them row boats.
Pretty easy rule to follow when learning or not learning how to shift a set of {sticks, Main box, Auxiliary box} Up shifting-{Don't shift the main box till your done shifting the auxiliary/Brownie} Down shifting on a grade-same.