This is an internally geared 2 speed hub dating back about 50 years. I plan to use this to build a 26 x 1 3/4 BE rim with #13 spokes for my light carrier Sekine. Light carrier is a misnomer as it weighs 36 kilograms.
The beauty of this 2 speed hub is that the gearing is internal, and, moreover, it doesn't use any cables. It is operated by pedaling backwards a third of a turn.
Here's a breakdown diagram and instructions.
The hub was manufactured by Yamamoto Iron Works based in Osaka. A quick check revealed that the company was founded in 1915, 100 years ago and is still in business.
The hub is beautifully chromed, and, by today's standards is heavy weighing in at over 2 kilograms.!
It has an oil port and oil cap. Typically these hubs were oiled every 6 months.
Traditional 40 count spoke.
Spoke holes are well machined and are the "keyhole"fashion also known in Japanese as the "Daruma" fashion.
This type of 2 speed hub where shifting is performed by pedaling backwards is known today as "kickback"and Sturmey-Archer has a complete line-up. But the specs are for modern-day bicycles and cannot be used on a traditional 40 spoke BE rim.