I am a T virgin? 1 week old and getting my car tomorrow - if it stops raining in Georgia.
It's a two speed rear axle that provides a low range
for the model T drivetrain.
Did they come stock or where they an add-on
The Ruckstell was an accessory added to T's to give an underdrive. It gives a superlow and a gear between high and low. They are wonderful for driving in hill country where low is too low and high is too high. Also, on a steep hill with a load, the super low will climb where the standard may stall. I believe they were one of the few accessories put on and sold by Ford dealerships. I have Ruckstells on 2 of my T's. After driving the touring for several years without one, I am very appreciative of it's advantages. If your new T has one, you are lucky.
The Model T as it came from the factory had two speeds: Too slow and not enough power. The Ruckstell cures both of those. It adds a gear about 30% lower than the standard ratio and gives an intermediate gear between low and high as well as a super low for deep mud, slow parades, and learning to drive.
The three best investments you can make to a T for driving in today's traffic and conditions are a Z head, a Stromberg OF carburetor and a Ruckstell.
To add just a bit to what "Dr. Noel" and Stan said, I believe that the Ruckstell is the only after-market accessory that Henry Ford approved and that is why they were installed as an option at Ford dealerships.
Found these on my pc
I have Ruckstells in all 3 of my T's. I use them for climbing the grade to my home. Also with practice to shift down for descending the grade. You have to be careful when shifting down to do it before you start down the grade, because the engine must speed up faster then the axle when you shift down. Do not shift down with the throttle up! They are also very good for going along the gravel drive 1180' too far to hold the low pedal down and high is too fast for this road. Ruckstell works just right. I also use it for going up the ramps to the trailer. My ramps are quite steep and I would have to get a run in low and if I am not quite straight have a problem. With Ruckstell and low, I can creep up the ramps and it is easy to load. Another good use is for parades. I shift into Ruckstell and pull the parking brake to the neutral position. Then I either tap the low pedal or the brake just enough to keep the speed without any jerking. I just set the idle slightly above normal idle and use the pedals. The Ruckstell is a very useful tool.
I would say Norman has it just about right. Stan too. I because I live where it's mostly flat drive mine just a bit different. I start out in LOW-LOW then shift the trans into high for LOW-HIGH, then shift the Ruchstell to high for HIGH-HIGH. Kinda like driving a three speed. I also have a set of 3:00-to-1 rear axle gears. The car is a 24 touring and if I had a roadster this is the set up I would use. In a coupe or sedan I would be using stock Ford ratio. In a sedan I might go with 4:1 gears and a Layne trans with OD for a bit of better top end. I have yet to shift a layne but hope to someday. A Ruckstell shifts soooo..... easly you'll wish your modern iron drove this nice.