The ALLEN was a three-bank, double-shift frontstrike machine produced roughly from 1920 or so.  Richard Uhlig first applied for patents for the machine in June 1917, although the application was renewed in September 1921.  The first patents were granted 1921-1922. 

At left, ALLEN portable from Tilman Elster collection, with serial number 3905.

Three variations of the ALLEN are known to exist; two three-bank production models, which differ in a number of details, and a single four-bank model not produced for sale. 

In fact, it should be pointed out that at least two reference works (written by Wilfred Beeching and Darryl Rehr) show a four-bank ALLEN portable.  These are the same machine, in the Dietz Collection at the Milwaukee Public Museum.  Peter Weil tells us that the four-bank example was assembled, at the museum, from parts found in boxes.  It is the only example known to exist.
Above, patent showing the double-shift mechanism whereby the carriage could move up or down from its center "neutral" position.  Below, the type-bar action.  The patent above is assigned to the Allen Typewriter Company, Allentown Pennsylvania; that below is assigned to the Allen Typewriter Manufacturing Company, Allentown, Pennsylvania (both PA. corporations.)  In 1927, a filing was made in New York registering the Allen Typewriter Manufacturing Company, which by this time was incorporated in Delaware.

Note the smaller illustration, top left of the above drawing.  This illustrates the slots, cut in the sides of the typewriter, in which guides for the carriage ride.  Travel adjustment screws are located in the top, and bottom of each slide; arresting of carriage motion is by these screws hitting the top or bottom of the slot in the side frame.
In the type-bar action illustration, note the horizontal rod on which the key lever is mounted; three such rods are used in the actual machine.  One of each of the three banks of keys is mounted on each rod.  Note also the projections slotted into the piece (20) mounted to the top of the segment.  These were designed to control impact of the type-bars at the print point.
At right, ALLEN portable serial 4341, Davis Collection.

This machine, which also incidentally bears the highest-known serial number of any ALLEN machine (at least in the list we have here), is of the second or later production variant.  Immediately, one notices the chromed ribbon spool supports - an unusual feature.  Keep in mind that the machines shown on this page thus far (Tilman Elster collection, Davis collection) are the second, or main production variant thought to have been begun 1920-1921.
In 2006, long-time typewriter collector / researcher BOB AUBERT took our friend Peter Weil on a trip to Allentown, Pennsylvania to view sites related to the manufacture of this machine.  Peter's photos are reproduced here. 

On the left, former factory of the Allen Typewriter Manufacturing Company; below, entrance to the factory with Bob on the left.
Next:  Complete, modern-day test and review of the ALLEN in full detail.
A brief line of historical data:  The first reference we have to this machine or the companies that made it is the January 1, 1917 filing for incorporation for the Allen Typewriter Company in Pennsylvania.  However, on April 18,1917 this same company was relisted as a "County Orphan" which indicates that it was bankrupt or otherwise defunct.  The first patent filing for the machine, by Uhlig, occurred June 20, 1917.  It was renewed September 9, 1921 and finally granted a patent April 11, 1922 assigned to Allen Typewriter Company, Allentown, Pennsylvania.  Another, filed later (October 13, 1917) was granted earlier (July 19, 1921) and yet another, filed August 1, 1917 was granted earlier as well, on March 28,1922 -- both again assigned to the Allen Typewriter Company, Allentown, Pennsylvania.

About one year after the last patent above was granted, another was filed by Uhlig covering a nearly identical machine; this was filed April 30, 1923 and granted December 1, 1925 and was assigned to the Allen Typewriter Manufacturing Company, Allentown, Pennsylvania, a Corporation of Pennsylvania.  As already mentioned, by 1927 the company was reincorporated in Delaware; this is indicated in filing in the state of New York July 28, 1927 with official address 93 Nassau St, New York, New York, 10038.

Bob Aubert, who has done a good deal of research on the ALLEN, feels that the machine probably didn't enter production until sometime after 1920 - and that correlates well with the renewal of the patent mentioned above in September 1921.  We can probably assume that production began roughly around this time, and Bob tells us that it ended in 1933.
This highly interesting advertisement for the ALLEN PROSPERITY BUSINESS COURSE comes from Peter Weil; it's a scan from an original in the Bob Aubert collection.  The Allen typewriter illustration is blown up above.  The advertisement dates from 1928.

Note that the machine shown is the same variant as pictured on this, and on the next page.

The ad is very interesting -- the idea was that with subscription to the typing / stenography course, after successful completion of the third lesson the Allen Typewriter was sent to you "free of charge."   The cost of the business course was $49.50 in payments, or else $44.50 cash.  The address for mailing the coupon was on Madison Avenue, New York City. 

Part of the ad:  "Allen supplies the machine!  A brand new simplified 3-bank Allen typewriter - NOT A RENEWED MACHINE OR A REBUILT ONE -- BUT ABSOLUTELY NEW! - is furnished free with each course -- and becomes your property when the course is completed.  The Allen typewriter is light, strong, compact, simple and scientific -- guaranteed for a whole year, built to last a lifetime.  It does all the work of a hundred dollar machine -- and is our free gift when you complete this easy, profitable course."  (See my note, at bottom of page.)
At right, detail from US Patent 1,410,854.  Inventor, Richard Uhlig; assigned to Allen Typewriter Company, Allentown Pennsylvania.  Filed August 1, 1917 and granted patent March 28, 1922. 

Note that this machine contains the key lever / type bar mechanism as found in the examples pictured on this page; also note that this patent is for the back-space mechanism seen on examples pictured on this page, and described in detail on the next page.  Clearly, then, this "main production variant" was designed in many essentials at least as far back as 1917.
It appears to us, more and more, if there were two separate production runs made on the two different models of three-bank Allen Typewriters.  We can't yet be sure of the overall dates of the first one, and it's very possible that it only began sometime in 1920-1921.  The best clue for this is the renewal of the patent application mentioned above.  All of the material prior to 1923 indicates Allen Typewriter Company.  Later, we have more activity centered 1925-1928 with the granting of a patent for the type-bar segment known to be used on the second-model Allen Typewriter, filing for Allen Typewriter Manufacturing Company in 1927, and actual advertisements in 1928 (Richard Polt has sent us a scan of an identical ad to the one seen above, from another different magazine, in a Summer 1928 issue.) 

We know by the patent documents that Allen Typewriter Company existed perhaps at least as late as April 1922; Allen Typewriter Manufacturing Company most certainly existed prior to December 1, 1925.  It may be that these two dates, which correspond well to the world-wide economic recession at that time, describe the break in production approximately.  It may well be true that the first model was introduced right as the recession hit, and that the second was released (by a new corporation, with new capital) as the effects of the recession waned, but entirely too late for acceptance of a three-bank double-shift machine.
Tony Casillo has sent us some wonderful digital photographs of his early, first-model ALLEN Typewriter.  On the right, Allen Typewriter trademark from the paper table, which appears to be a winged three-character type slug!
Inspection of these photos makes several things immediately obvious.  First is the use of the same patented Uhlig type-bar segment, with projections, as seen in the patent drawing.  Second, a large number of appurtenances are identical to the later machines -- not just the shift lock and back-space, but the paper bail, the mainspring, the paper release, the guide slots in the side frames for the double-shift carriage, and more. 

While there are differences, too (for example, the ribbon spools move up and down with the carriage, and the casing is different) it's now obvious these are the same design, basically - improved in the later model.
The rear of the machine is of further interest; note the margin set rack, identical to the later machine's.  Note the mainspring, and mounting rod for the paper bail.  Note also the machined bar stock frame for the carriage.

Of particular interest is the inscription-- indicating "patents pending."  This limits production to sometime before the patents seen earlier were all finally granted - ie, sometime before 1922.  However, note the company name - Allen Typewriter Co. - on the front frame.
With the "patents pending" inscription, and the company name we can be pretty sure the machine was actually introduced sometime into the 1920's but prior to 1925 for sure.

A big THANK YOU to Tony Casillo for coming through with pictures of this rare machine!  (This machine is serial no. 207.)
Author's note on "Allen Prosperity Business Course."     Friends, don't be fooled -- this is a very thinly disguised attempt to sell the Allen Typewriter by covering the sale with backwards marketing.  What I mean by "backwards marketing" is this -- very many typewriters of the day were shipped with some kind of free, or nearly free, material.  You'd get at least instructions, and maybe a typing chart, and maybe even a short typing course (for instance, the Harris Visible No. 4 instruction manual contained a short course in typing along with basic directions.)  Now, as is mentioned in this advertisement, some rebuilt machines offered what was described as a "complete typing course" free with the purchase of a machine.  That seemed better, didn't it?  After all, not only do you get a fully workable typewriter at a considerable savings, but you get a course as well so that you can either use the machine for your job, or for making money on the side.  Again, a number of manufacturers of brand-new machines also used advertising angles like this -- for instance, on another page we show a flyer for the Rex Visible No. 4 describing how you can make money at home, in your spare time, limited only by your ability to find ways to use the typewriter.

In the specific case of the Allen Typewriter, they've reversed things on us.  They're trying to sell us, directly, a course in office and business practices (stenography and typing) to help us move forward in our jobs.  The offer describes how a young lady rocketed to success and happiness after having learned these skills "the Allen way."  The ad makes the typewriter seem like a free premium for signing up.  Of course, no matter what the course itself actually cost in those days, one imagines it couldn't have really been anything near the $49.50 in installments or $44.50 cash price.  No, that's a lot closer to the asking price of such a portable typewriter of the day - and even though the Allen Typewriter was about as cheaply made as you can get, it would still have been most of this total price.  No, this isn't really an offer for a business course - it's an offer for the typewriter, but one in which the typewriter plays second fiddle.  That's why I find this advertisement so fascinating.  You do have to wonder, though... did the designer know this was to be the angle from the start?