Any video that starts off with two minutes of motorcycle formation riding has got to be good. If the grainy black and white video didn’t tip you off that this was made in a different time the helmetless riders standing on the seats of moving motorcycles certainly would have. But there is a purpose to this exposition. A single line of motorcycles riding shoulder to shoulder as they go around a curve illustrates why a differential is necessary and soon after you’ll find out how one works.
Two wheels mounted on one axle need to turn at different speeds as a vehicle goes around a corner or one of the wheels must slip to accommodate the speed difference. The differential is necessary to allow for these different turning rates while still letting both wheels connect to the power train. We were surprised to learn from the video after the break that early automobiles got around this issues by powering only one of the four wheels.
This instructional video is a prefect compliment to the fluid coupling video we saw in the last installment of Retrotechtacular.