This fan is a three speed, DC fan and runs absolutely perfectly with good speed separation. There is little extra room, if any, to allow for mounting a rectifier under the base to allow the fan to be plugged into AC current. That is easily rectified by putting a rectifier inline with the power cord and taping it to the cord.
Right: The rear of the fan is as attractive as the rest of it. Brush caps are made of what looks to be wood. Lubrication is by front and rear oil cups with an unusual feature on fans; a small opening on top of the front and rear bearing housings that allows one to add oil to the bearings directly. I don't know why this was done since a filling of the oil cups will last a long time.
The 9" Diehl desk fan was discontinued for the 1909 model year and replaced with a similar 8" model.
Serial No. 180154. Due to the rarity of these (and most Diehl) fans the number may have been sequential beginning with Diehls' earliest fans, the first direct drive ceiling fan of 1887.
Right: Note the small well on top of the bearing housing which allows addition of oil directly to the bearing. No cap also would allow dirt to enter. Brush cap on the left is made of wood.
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Feb 21, 1905
Left: The first of the ornate Diehl desk fans used a unique square wire cage strut which wraps around the rear cage ring as well as an "S" wire. Making a reproduction of these would be a difficult task. Later versions used the more commonly seen flat cage strut as was common with most other fan makers.
Other Diehl patents: No.325, 576 July 10, 1906