Complex sentence: Although based on a tractor, when both the loader and the backhoe are permanently attached the vehicle is almost never called a "tractor", is not generally used for towing and usually does not have a power take-off (PTO).
Split into simpler sentences: Although based on a tractor, a backhoe loader is almost never called a "tractor" when both the loader and the backhoe are permanently attached. Backhoe loaders are also not generally used for towing and usually do not have a power take-off (PTO).