Front Headlamp (Headlight) Part 6

次回、この記事の日本語版を投稿します。

In this Front Headlamp (Headlight) series, so far we have covered:

Part 1: Vintage Japanese bicycle headlamps
Part 2: Various mounting locations and hardware (brackets)
Part 3: Features typically found on headlamps before 1955
Part 4: Features typically found on headlamps after 1955
Part 5: Headlamps equipped with pilot lights, speedometer and odometer

In this post, Part 6, we will look at a simple feature that is often overlooked, the focus beam control.
The focus beam control allows the user to select the width of the beam, from wide beam (floodlight) to narrow beam (spotlight).　Two types, external, and, internal focus beam control.  Let's take a look.

External focus beam control
Up till around 1955, some models, typically the high powered 12V ~ 20V models were equipped with an external focus beam control which consisted of a dial on the back of the headlamp housing.  This dial allowed the rider to regulate the focus of the beam while riding. Pay attention to the dials on the back of the lamp housing in the following examples.



 

Internal focus beam control
Unlike the external focus beam control, the internal type did not allow the rider the luxury of adjusting the beam focus while riding, and had to be set before getting on the bicycle.  The beam focus was set by opening the cover and removing the socket with lightbulb intact.  The sides of the socket have stepped notches, and, the pins on the side of the lightbulb cap fit in these notches.  The top notches are for wide, floodlight beam, and, the lower notches are for narrow, spotlight beam.

Open cover

Socket with lightbulb intact

Pull out

Set beam focus using notched socket grooves

Lightbulb cap pins

Socket stepped notches
The higher the step, the wider the beam.