from The Century Dictionary.
- noun A cover or casing placed around gears to keep out dirt and grit, and also to protect the workmen from being caught by the gears and injured.
Sorry, no etymologies found.
Air and gasoline are mixed in the accelerator carburetor gear-case 55 56
The gear-case is on one side of the frame and the chain on the other, and the frame itself was a marvel of ingenuity misapplied.
Thus encouraged, he set to work to refix the gear-case.
"If anything goes wrong with your gear-case, sell the machine and buy a new one; it comes cheaper."
He then said that while he was about it he would see to the chain for me, and at once began taking off the gear-case.