Have you ever looked at a nameplate on various old Royal vacuum cleaners through the years and ever thought to yourself just how long they used each of these variations?
Prior to 1970, the nameplate was riveted to the underside of the motor assembly (a la Kirby) in the middle of both sets of wheels. On a black background, we see the voltage (115 AC/DC), followed by the serial # cast (format is: (MODEL)-(SERIAL)) onto a silver background, and WATTS: 350 (350 watts divided by 115 volts is 3.2 amps) to the right of the top row. The middle row shows the model # followed by the company (ROYAL APPLIANCE MFG. CO., CLEVELAND, OHIO). And the bottom row shows us the patents then covered, and the text "THIS MACHINE EMBODIES INVENTIONS COVERED BY ONE OR MORE OF THE ABOVE PATENTS. OTHER PATENTS PENDING."
Prior to 1954, the nameplate also listed the company as either "THE P. A. GEIER COMPANY" (before about 1951) and "THE ROYAL VACUUM CLEANER CO." (circa 1951-54).
After 1970, the nameplate changed to one which was applied to the back side of the nozzle by the front wheels. On top, the first things we see are the model # (880, for example) and the company name:
ROYAL APPLIANCE MANUFACTURING CO.
HIGHLAND HEIGHTS, OHIO 44143
The middle row lists the serial number, an example being: 07J-N-15980. The serial # is formatted thus:
0 = calendar year (1970)
7 = decade of calendar year (1970s)
J = calendar year month (September) ("I" was skipped to avoid confusion with the number "1," so "M" is used for the month of December)
N = indicates the line and production shift the vacuum came off of.
15980 = production sequence number.
Next row is the voltage rating (115; 120 after about 1982-83) and the motor rating in watts (400). 400 watts / 115 volts amounts to 3.5 amps. After about 1975, the motor rating was changed to read 3.0 amps.
Next row, we see the list of patents covered in this vacuum to that point, followed by "MANUFACTURED UNDER ONE OR MORE OF THE ABOVE PATENTS - OTHER PATENTS PENDING."
After about 1975-76, the patents were removed from the nameplate, and the motor rating changed to "AMPS 3.0" (later 4.5). (1.2 or 1.8 on the Prince 501, and 8.0 for the canisters/tanks) Newly included information is the Underwriters' Laboratories (U.L.) circle symbol and "CLEANING MACHINE 760G LISTED." "760G" is the U.L. code corresponding to Royal. Prior to this point, the U.L. info was in the form of a decal applied to the near-bottom of the handle assembly, or on a yellow decal applied just right of the nameplate, with the text "CLEANING MACHINE - (U.L. symbol) - 760G LISTED."
In January 1977, the serial # was revised a bit so that the first two digits are the actual calendar year (e.g. "78" is 1978, instead of "87" which after 1/85, would, of course, indicate year 1987). Then, around September/October 1978, the calendar month code preceded the calendar year (so one sees "C79" for March 1979, instead of "79C").
Then, in January 1985, it changed again: We now see Royal's corporate logo on the top left, followed by "ROYAL APPLIANCE MFG. CO., Cleveland, Ohio 44143. Below all that, we see fields for "MODEL NO.," "SERIAL NO.," "VAC." (Volts AC), "HZ." (Hertz), "AMPS." and then concludes with the U.L. corporate symbol and "CLEANING MACHINE, 760G LISTED." The serial # format now looks like this: A85A001341. It breaks down as: A85 = January 1985 (the calendar month code is a letter from A-L, and this time includes "I" to indicate month September); A = line/shift where vacuum came off of; and 001341 = sequence number.
They revised it slightly in January 1986, so that it looks like this: we again see Royal's corporate logo followed by company name and city/zip of corporate HQ's on the top of the decal. Vital statistics remain unchanged (model, serial, volts, etc.). This time, we see "MADE IN U.S.A." before the U.L. information, and the words "CLEANING MACHINE" are removed. All text is in black instead of medium blue. From about 1987-92, the words "MADE IN U.S.A." were also seen below the Royal corporate logo.
I hope this may all help you...
~Ben

Prior to 1970, the nameplate was riveted to the underside of the motor assembly (a la Kirby) in the middle of both sets of wheels. On a black background, we see the voltage (115 AC/DC), followed by the serial # cast (format is: (MODEL)-(SERIAL)) onto a silver background, and WATTS: 350 (350 watts divided by 115 volts is 3.2 amps) to the right of the top row. The middle row shows the model # followed by the company (ROYAL APPLIANCE MFG. CO., CLEVELAND, OHIO). And the bottom row shows us the patents then covered, and the text "THIS MACHINE EMBODIES INVENTIONS COVERED BY ONE OR MORE OF THE ABOVE PATENTS. OTHER PATENTS PENDING."
Prior to 1954, the nameplate also listed the company as either "THE P. A. GEIER COMPANY" (before about 1951) and "THE ROYAL VACUUM CLEANER CO." (circa 1951-54).
After 1970, the nameplate changed to one which was applied to the back side of the nozzle by the front wheels. On top, the first things we see are the model # (880, for example) and the company name:
ROYAL APPLIANCE MANUFACTURING CO.
HIGHLAND HEIGHTS, OHIO 44143
The middle row lists the serial number, an example being: 07J-N-15980. The serial # is formatted thus:
0 = calendar year (1970)
7 = decade of calendar year (1970s)
J = calendar year month (September) ("I" was skipped to avoid confusion with the number "1," so "M" is used for the month of December)
N = indicates the line and production shift the vacuum came off of.
15980 = production sequence number.
Next row is the voltage rating (115; 120 after about 1982-83) and the motor rating in watts (400). 400 watts / 115 volts amounts to 3.5 amps. After about 1975, the motor rating was changed to read 3.0 amps.
Next row, we see the list of patents covered in this vacuum to that point, followed by "MANUFACTURED UNDER ONE OR MORE OF THE ABOVE PATENTS - OTHER PATENTS PENDING."
After about 1975-76, the patents were removed from the nameplate, and the motor rating changed to "AMPS 3.0" (later 4.5). (1.2 or 1.8 on the Prince 501, and 8.0 for the canisters/tanks) Newly included information is the Underwriters' Laboratories (U.L.) circle symbol and "CLEANING MACHINE 760G LISTED." "760G" is the U.L. code corresponding to Royal. Prior to this point, the U.L. info was in the form of a decal applied to the near-bottom of the handle assembly, or on a yellow decal applied just right of the nameplate, with the text "CLEANING MACHINE - (U.L. symbol) - 760G LISTED."
In January 1977, the serial # was revised a bit so that the first two digits are the actual calendar year (e.g. "78" is 1978, instead of "87" which after 1/85, would, of course, indicate year 1987). Then, around September/October 1978, the calendar month code preceded the calendar year (so one sees "C79" for March 1979, instead of "79C").
Then, in January 1985, it changed again: We now see Royal's corporate logo on the top left, followed by "ROYAL APPLIANCE MFG. CO., Cleveland, Ohio 44143. Below all that, we see fields for "MODEL NO.," "SERIAL NO.," "VAC." (Volts AC), "HZ." (Hertz), "AMPS." and then concludes with the U.L. corporate symbol and "CLEANING MACHINE, 760G LISTED." The serial # format now looks like this: A85A001341. It breaks down as: A85 = January 1985 (the calendar month code is a letter from A-L, and this time includes "I" to indicate month September); A = line/shift where vacuum came off of; and 001341 = sequence number.
They revised it slightly in January 1986, so that it looks like this: we again see Royal's corporate logo followed by company name and city/zip of corporate HQ's on the top of the decal. Vital statistics remain unchanged (model, serial, volts, etc.). This time, we see "MADE IN U.S.A." before the U.L. information, and the words "CLEANING MACHINE" are removed. All text is in black instead of medium blue. From about 1987-92, the words "MADE IN U.S.A." were also seen below the Royal corporate logo.
I hope this may all help you...
~Ben
