transmission trouble with a 1974 5550 ford backhoe

Today it is 9 degrees F outside, I went to use the ford 5550 backhoe it would not move forwards or in reverse, before the cold it worked just fine. I could bury the front bucket in the ground and it would spin the wheels and keep pushing. I only use it in 1st or 2nd low range gear around the barn, any ideas on what the problem would be? Also does this machine have a transmission filter on it and if so where is its location. Any help would be appreciated thank you.

I got a '73 5550, the filter should be up behind the radiator on the left side of the engine. An aluminum mount with two hoses and a spin on filter.

Our beasts don't have all the electrical solenoids and switches the newer 'gimp' qualified operator ones do, so it's probably a lip seal getting hard and not sealing in the cold. There are two clutch packs with apply pistons to engage the clutches. Cold plastic won't completely conform to the space and until the oil heats up and softens the plastic, no go....

Only other rubber or plastic in the tranny are some huge O-rings around the front pump which pressurizes the tranny, but those would be peeing oil, so it's back to the lip seals. Let it sit until it warms up, you don't want those seals to fracture. Then you get to split the tractor and rebuild the trans.

When I was learning about automatic transmissions 40 years ago, our instructor mentioned Chrysler had to install special lip seals in the cars and trucks sold around the Canadian border, north, and Alaska. There was 300psi to apply the rear clutch and that would shatter the seal. 5550 are seriously strong buggers, an oldtimer was watching me move some dirt with mine, he said to me that hoe will probably still be around and running when all of us are dead...

Lonestar:
If your machine was working in warmer weather and then not working in cold weather the first thing I would check would be the transmission oil. When was the last time you changed the oil in the transmission? Does the oil look milky? Over time, condensation collects inside the cavities of equipment, especially if that part of the machine heats up and cools down. I wonder if there is some ice blocking an oil passage and not letting the clutch packs engage. The wrong viscosity oil may also be the problem in really cold weather. Check your oil level first, then start your machine and let it run until it's good and warm and then try moving the machine. If this doesn't work then I would contact a New Holland dealer and ask them what the correct viscosity oil that should be used for your 5550 backhoe. I am looking forward to reading your next post to see what you have found.