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Armstrong Bros. Tool Company

[Strong Arm Logo from 1914 Trademark]
Logo from 1914 Trademark.

Table of Contents








Introduction

Company History

The Armstrong Bros. Tool Company began in 1890 as a maker of bicycle parts and service tools, founded in Chicago, Illinois by four brothers. Their first manufacturing operations were conducted literally from a backyard wooden shed, and the brothers also operated a retail store for their bicycle parts.

In 1895 Armstrong introduced what would become their first major product, a tool holder for lathe cutting bits. Developed from their own manufacturing operations, the Armstrong tool holder was a forged handle that accepted small interchangeable cutting bits, thereby replacing the individually forged cutting tools previously required. This dramatically reduced the time and expense involved in making lathe cutting tools, and it's fair to say that these tool holders revolutionized the industry.

With the success of the tool holder, in 1900 Armstrong built their first real factory at 617 Austin Avenue in Chicago. This was replaced a few years later in 1905 by a 100,000 square foot brick factory at 317 North Francisco Avenue, a site they would occupy for many years.

Up until 1909 Armstrong concentrated primarily on tool holders and related products, but in 1909 they started producing a line of drop-forged wrenches. This line of tools continued to expand over the years.

[1920 Notice for Armstrong B-20 Catalog]
1920 Notice for Armstrong B-20 Catalog. [External Link]

By 1920 Armstrong was offering three sizes of "Aero" tappet wrenches made of chrome-nickel steel, an early example of alloy steel usage for tools. The notice at the left, published on page 748 of the November, 1920 issue of Railway Mechanical Engineer, announces Armstrong catalog B-20 and notes the inclusion of "Aero" tappets among the new products.

In 1948 the company moved from the Francisco Avenue site to 5200 West Armstrong Avenue, where they remain today. A second manufacturing facility in Fayetteville, Arkansas was added in 1974.

In 1994 Armstrong was acquired by the Danaher Group, a conglomerate with other tool company holdings including Allen, K-D, Matco, and Moore Drop Forging. Armstrong operates now as the Industrial Hand Tools division of Danaher.

More information on the history and development of Armstrong is available from the company's www.armstrongtools.com [External Link] web site.


Patents

Armstrong was a highly innovative organization from its beginning, and received (or licensed) many patents over the years. Their early catalogs even include a list of patent dates in the front, a thoughtful addition that would have been more useful if the patent numbers had been included as well.

Table 1. Armstrong Bros. Issued and Licensed Patents
Patent No.InventorFiledIssuedDescriptionExamples
492,381 G. Armstrong   02/28/1893 Tool Holder  
535,440 J. Armstrong   03/12/1895 Tool Holder  
      04/19/1898 Date Noted in Catalog  
613,950 H.D. Williams et al05/28/189011/08/1898Levered Ratchet Drill  
658,478 H.D. Williams et al02/15/189709/25/1900Mechanical Movement for Ratchet Drill  
      08/28/1900 Date Noted in Catalog  
      09/25/1900 Date Noted in Catalog  
      01/29/1901 Date Noted in Catalog  
675,184 J. Armstrong 1/20/1900 05/28/1901 Tool Holder  
725,019 J. Armstrong05/29/190204/14/1903Tool Holder  
779,516 J. Armstrong03/21/190401/10/1905Process of Cutting Steel  
914,012 P. Armstrong11/15/190603/02/1909Ratchet Drill  
960,769 J. Armstrong09/18/190806/07/1910Knurling Tool  
1,214,498 J. Armstrong01/14/191602/06/1917Tool Holder  
      07/10/1917 Date Noted in Catalog  
      10/09/1917 Date Noted in Catalog  
1,252,031 W.S. Robinson 12/26/1916 01/01/1918 Planer-Tool Holder  
1,277,481 W.S. Robinson08/11/191709/03/1918Tool Holder  
1,343,257 J.C. Fletcher07/17/191906/15/1920Tool Holder  
1,495,751 J.V. Larson11/10/192205/27/1924Adjustable Wrench  
1,584,347 L.F. Armstrong 04/23/1925 05/11/1926 Tool Holder  
      01/04/1927 Date Noted in Catalog  
1,621,226 S.J. Welter 09/19/1923 03/15/1927 Milling Cutter  
1,653,326 S.J. Welter 04/23/1925 12/20/1927 Chain Pipe Vise  
1,676,210 P. Armstrong11/29/192607/03/1928Pipe Wrench  
1,732,549 L.F. Armstrong02/17/192810/22/1929Wrench for Tool Holder  
2,008,367 H.A. Rhinevault10/26/193407/16/1935Locking Detent for Sockets  
2,078,475 S.J. Welter 12/07/1934 04/27/1937 Tool Holder  
2,162,359 H.A. Rhinevault08/22/193606/13/1939Socket Locking Device  
2,190,585 H.A. Rhinevault08/22/193602/13/1940C Clamp  
2,193,984 H.A. Rhinevault04/16/193703/19/1940Reversible Ratchet Wrench  

Trademarks

Armstrong registered a number of trademarks, including the well-known Strong-Arm logo, the Armstrong name, and "Armaloy", their trademark for alloy-steel tools.

Table 1B. Armstrong Bros.: Registered Trademarks
Description First Use Date Filed Date Issued Registration Notes
Armstrong 01/01/1892 11/08/1916 02/27/1917 115,574 Notes use on wrenches.
Armstrong 01/01/1892 02/26/1957 10/01/1957 652,375  
Strong Arm Logo 09/01/1897 10/19/1910 03/31/1914 95,975 "Strong Arm" logo.
Armaloy 08/01/1946 05/28/1956 01/22/1957 640,308 Used for alloy steel wrenches.

Tool Identification

Armstrong tools are generally clearly marked with the Armstrong name or trademarked logo, and so are easy to identify. Early tools may be marked with symbol consisting of an "A" within a triangle, referred to here as the A-Triangle logo.


Manufacturing Dates

Armstrong is not known to have used any kind of a date code marking for its tools. Without such markings, any estimation of manufacturing dates will have to be based on other information, such as the design or style, patents, trademarks, finish, and so on.

Probably the most important date marker for Armstrong tools is the "Armaloy" trademark, registered with its first use in late 1946 and (presumably) marked on alloy-steel tools shortly after that. In this article we'll assume a manufacturing date of 1947 or later for Armaloy-marked tools.

Another useful indication of the manufacturing date follows from the 1978 introduction of a new product numbering system. The new system assigned a five digit model number to all tools, with part of the number indicating a category for the tool and the final digits typically encoding the size. The new model numbers were first used in Armstrong catalog 880 of 1978, and that catalog includes a cross-reference table of old and new numbers.

The following observations and events may be helpful in estimating the manufacturing date for some tools.

  • Armstrong-Vanadium Marking. Alloy steel tools had forged-in "Armstrong-Vanadium" markings from the mid 1920s until the early 1930s.
  • Chrome-Vanadium Marking. The forged-in "Armstrong-Vanadium" marking was replaced by a stamped "Chrome-Vanadium" (or equivalent) marking in the early 1930s. However, the Armstrong catalogs from the 1930s continued to illustrate tools with "Armstrong-Vanadium", and some examples may have been marked with a stamped "Armstrong-Vanadium". These specific alloy markings are believed to have remained in use until around 1942, after which they were typically replaced by a generic "Alloy Steel" or equivalent.
  • Alloy Steel Marking. In Catalog 39b Armstrong changed the steel specification for sockets and drive tools to "Alloy Steel" from the prior "Chrome Vanadium Steel". This was the second of the interim wartime-era catalogs and was likely published around 1944. It's likely that the actual tool markings were changed before the catalog publication, due to wartime material shortages, so an estimate of 1942 for the beginning of this marking is probably reasonable. Since Armstrong began using the "Armaloy" trademark for alloy tools in late 1946, the "Alloy Steel" marking likely indicates production in 1942-1946.
  • Hi-Tensile Marking. This marking is believed to have been first used during the 1942-1945 war years to indicate the substitution of high tensile strength steel where a chrome vanadium alloy would normally have been used. Armstrong later used "Hi-Tensile" or "Hi-Ten" on some of its carbon steel tool line, but this usage can be distinguished by the model numbers.
  • Armaloy Trademark. Marked on alloy steel tools, first used in late 1946. In use until 1980s?
  • Locking Hole for Sockets. From the early 1930s onward Armstrong provided a single locking hole in the drive end of sockets, instead of recesses in the drive wall. The locking hole remained in production until at least the 1970s, but was eventually replaced by recesses on the drive end walls.
  • Wide-Groove Style for Sockets. Sockets were made with a single wide groove at the base beginning in the late 1940s, replacing the earlier knurled band. The wide-groove style remained in use until approximately 1970.
  • Narrow-Groove Style for Sockets. Sockets were made with a single narrow groove at the base beginning around 1970.
  • Drive-End Recesses for Sockets. Armstrong began using recesses on the drive end of sockets sometime in the 1970s or later, replacing the locking holes used up to that time. Examples are known of narrow-groove style sockets with drive-end recesses.
  • Five-Digit Model Number System. In 1978 Armstrong switched to a five-digit model numbering system, first published in catalog 880.
  • Double-Groove Style for Sockets. Sockets were made with a two narrow grooves at the base beginning sometime after 1978.

References and Resources

Photographs and observations of particular tools are based on items in the Alloy Artifacts collection.


Catalog Coverage

Our current catalog resources are summarized in the table below.

CatalogDateFormatNotes
B-20 1920 Booklet Lists three sizes of "Aero" tappet wrenches in chrome-nickel steel.
Notice for catalog in November, 1920 issue of Railway Mechanical Engineer.
B-23 1923 Booklet Lists "Aero" tappet wrenches in chrome-nickel steel.
B-27 1927 Booklet Armstrong-Vanadium open-end and tappet wrenches available.
Includes price update dated January 1, 1928.
B-27A 1928 Booklet No sockets tools listed.
B-35 1935 Booklet Includes sockets and drive tools.
Largest socket tools in 1 inch hex drive X-Series.
C-39 1939 Half Sockets and tools for 1 inch drive now square drive in XX-series.
Combination ("Multitype") wrenches offered.
C-39a 1942? Half Insert mentions War Production Board. Notes Army-Navy "E" production award.
All socket tools specify "Chrome-Vanadium Steel". Socket tools in 9/32-drive available.
X-series model numbers for 1 inch drive, no cross-bar hole for sockets.
C-39b 1944? Half Notes Army-Navy "E" production award.
All socket tools specify "Alloy Steel". Socket tools in 1/4-drive NM-series available.
S-48 1948 Half Armaloy trademark in use
57 1956 Full  
700 1961 Full S-91 ratchet available with round knurled handle
700-A 1966 Full Sockets still with wide-groove design.
820A 1973 Full S-91 ratchet with flat-sided knurled handle. Sockets with narrow-groove design.
880 1978 Full Introduction of new 5-digit product numbering system.
Sockets still with narrow-groove design.

Armstrong tools were distributed by many industrial supply companies, and the catalogs from these suppliers may contain helpful information on Armstrong products. We'll add references to some of these as time permits.


Carbon Steel Tools

Carbon steel was the dominant material for toolmaking until around the mid 1920s, when various alloy steels came into general use.


Early Production


No. 2 7/16 Toolpost Wrench

[Armstrong No. 2 7/16 Toolpost Wrench]
Fig. 1A. Armstrong No. 2 7/16 Toolpost Wrench, with Inset for Reverse Detail, ca. 1900-1920.

Fig. 1A shows an early Armstrong No. 2 7/16 toolpost wrench, marked with "Armstrong" forged into the shank, with "No. 2" forged into the reverse.

The overall length is 5.0 inches, and the finish is plain steel.


No. 5 7/8 Toolpost Wrench

[Armstrong No. 5 7/8 Toolpost Wrench]
Fig. 1B. Armstrong No. 5 7/8 Toolpost Wrench, with Inset for Reverse, ca. Early to Mid 1920s.

Fig. 1B shows an early Armstrong No. 5 7/8 toolpost wrench, stamped with "Armstrong Bros. Tool Co." and "Chicago, U.S.A." plus the model number on the face, with "1/2 NUT" on the reverse. The shank is also marked with the Strong-Arm logo forged into the front, with "5" forged into the reverse.

The overall length is 8.1 inches, and the finish is plain steel.

The reverse face marking is a reference to the older U.S.S. size convention for the 7/8 opening.


23A 3/8x7/16 Open-End Wrench

[Armstrong 23A 3/8x7/16 Open-End Wrench]
Fig. 2A. Armstrong 23A 3/8x7/16 Open-End Wrench, with Inset for Reverse, ca. Early 1920s.

Fig. 2A shows an early Armstrong 23A 3/8x7/16 open-end wrench, stamped "Armstrong" and "Chicago, U.S.A." on the face, with the A-Triangle logo forged into the shank. The reverse faces are stamped with the opening sizes as "1/4 CAP" and "3/16 CAP", references to the older Hex Capscrew size convention.

The overall length is 4.0 inches, and the finish is plain steel.


1623-C 7/16x9/16 Check-Nut Wrench

[Armstrong 1623-C 7/16x1/2 Check-Nut Wrench]
Fig. 2. Armstrong 1623-C 7/16x1/2 Check-Nut Wrench, with Inset for Reverse, ca. Early 1920s.

Fig. 2 shows an early Armstrong 1623-C 7/16x1/2 check-nut wrench, stamped "Armstrong Bros. Tool Co." and "Chicago, U.S.A." on the face, with the A-Triangle logo forged into the shank. The reverse faces are stamped with the opening sizes as "5/16 S.A.E." and "1/4 S.A.E.", references to the older S.A.E. size convention.

The overall length is 4.4 inches, and the finish is plain steel.

The wrench is listed in the automotive section of the 1921 Armstrong catalog.


629C 3/4x7/8 Check-Nut Wrench

[Armstrong 629C 3/4x7/8 Check-Nut Wrench]
Fig. 3. Armstrong 629C 3/4x7/8 Check-Nut Wrench, with Inset for Reverse Detail.

Fig. 3 shows an Armstrong 629C 3/4x7/8 open-end check-nut (thin) wrench, marked "Armstrong Chicago U.S.A." on the face, with a forged-in A-Triangle logo on the shank. The overall length is 6.5 inches.

The inset shows the reverse side markings, with the model number "629" in raised letters and "C" stamped into the shank. The mix of forged-in and stamped markings probably indicates that one forged blank could be used to make several wrench models.


661D 5/16x3/8 S-Shaped Wrench

[Armstrong 661D 5/16x3/8 S-Shaped Wrench]
Fig. 4. Armstrong 661D 5/16x3/8 S-Shaped Wrench, with Inset for Reverse Detail, ca. Late 1920s.

Fig. 4 shows an Armstrong 661D 5/16x3/8 S-shaped open-end wrench, marked with the A-Triangle logo forged into the shank, with the model number forged into the reverse.

The overall length is 4.0 inches, and the finish is plain steel.

The Armstrong catalog lists this model for use with hex capscrew sizes 1/8 and 3/16, corresponding to the fractional opening sizes 5/16 and 3/8, as stamped on the wrench faces. The use of A-Triangle logo with fractional size markings suggests production in the late 1920s.


807 1-1/16 Single-Box Wrench

[Armstrong 807 1-1/16 Single-Box Wrench]
Fig. 5. Armstrong 807 1-1/16 Single-Box Wrench, with Inset for Reverse Detail.

Fig. 5 shows an early Armstrong 807 1-1/16 hex single-box wrench, marked with the model number forged into the shank, and with the A-Triangle logo forged into the reverse.

The overall length is 9.3 inches, and the finish is plain steel.


903 11/16 Single-Open Structural Wrench

[Armstrong 903 11/16 Single-Open Structural Wrench]
Fig. 6. Armstrong 903 11/16 Single-Open Structural Wrench, with Inset for Side View, ca. Early to Mid 1920s.

Fig. 6 shows an early Armstrong 903 11/16 open-end structural wrench, marked with the model number and A-Triangle logo forged into the shank, and stamped "Hardened" on top.

The overall length is 8.9 inches, although part of the pointed handle appears to have been broken off. (The 1923 catalog specified a length of 9.5 inches.) The finish is plain steel.

The opening is stamped "3/8 NUT", a reference to the older U.S.S. size convention. The 1923 Armstrong catalog noted that this wrench was sized for "rough nuts", with the milled opening 1/32 oversize.


Later Carbon-Steel Tools

Armstrong continued to produce certain tools in carbon steel models even after the widespread adoption of alloy steels, for applications where the greater strength (but higher cost) of alloy steel was not needed.


31 25/32x7/8 Open-End Wrench

[Armstrong 31 25/32x7/8 Open-End Wrench]
Fig. 7. Armstrong 31 25/32x7/8 Open-End Wrench, with Inset for Side View.

Fig. 7 shows an Armstrong 31 25/32x7/8 open-end wrench, stamped on the face with "Armstrong" and "Made in U.S.A." with the Strong-Arm logo.

The overall length is 9.4 inches, and the finish is gray paint with polished faces.


5B782 (Caterpillar) 9/16x5/8 Open-End Wrench

[Armstrong 5B782 9/16x5/8 Open-End Wrench]
Fig. 8. Armstrong 5B782 9/16x5/8 Open-End Wrench.

Fig. 8 shows an Armstrong 5B782 9/16x5/8 open-end wrench, stamped "Made in U.S.A." with the Strong-Arm logo on the face.

The overall length is 6.6 inches, and the finish is plain steel with traces of black paint,

Several sources have suggested that open-end wrenches in the 5B78x model series were made for Caterpillar, so this wrench has been provisionally identified as production for Caterpillar.

Similar wrenches were also produced by Billings and can be seen as the Billings 5B784 Wrench and Billings 5B785 Wrench.


5B786 (Caterpillar) 1-1/16x1-1/8 Open-End Wrench

[Armstrong 5B786 1-1/16x1-1/8 Open-End Wrench]
Fig. 9. Armstrong 5B786 1-1/16x1-1/8 Open-End Wrench, with Inset for Marking Detail.

Fig. 9 shows an Armstrong 5B786 1-1/16x1-1/8 open-end wrench, stamped "Made in U.S.A." with the Strong-Arm logo on the face.

The overall length is 11.7 inches, and the finish is plain steel with traces of black paint,

Several sources have suggested that open-end wrenches in the 5B78x model series were made for Caterpillar, so this wrench has been provisionally identified as production for Caterpillar.


624-A 7/16x9/16 Check-Nut Wrench

[Armstrong 624-A 7/16x9/16 Check-Nut Wrench]
Fig. 10. Armstrong 624-A 7/16x9/16 Check-Nut Wrench.

637 1-1/16x1-1/4 Check-Nut Wrench

[Armstrong 637 1-1/16x1-1/4 Check-Nut Wrench]
Fig. 11. Armstrong 637 1-1/16x1-1/4 Check-Nut Wrench.

Fig. 11 shows a later checknut wrench, an Armstrong 637 1-1/16 by 1-1/4 thin open-end wrench, stamped on the face with "Armstrong" and "Made in U.S.A." with the Strong-Arm logo.

The overall length is 10.1 inches, and the finish is gray paint with polished faces.


607-A 1-1/8 Single-Open Check-Nut Wrench

[Armstrong 607-A Single-Open Check-Nut Wrench]
Fig. 12. Armstrong 607-A 1-1/8 Single-Open Check-Nut Wrench.

Fig. 12 shows an Armstrong 607-A 1-1/8 single-open check-nut wrench, stamped "Armstrong" and "Made in U.S.A." with the Strong-Arm logo on the face. The shank is stamped with the model number and also has a forged-in Strong-Arm logo, visible at the left.

The overall length is 8.5 inches, and the finish is gray paint with polished faces.


661G 3/8x1/2 S-Shaped Open-End Wrench

[Armstrong 661G 3/8x1/2 S-Shaped Open-End Wrench]
Fig. 13. Armstrong 661G 3/8x1/2 S-Shaped Open-End Wrench.

Fig. 13 shows an Armstrong 661G 3/8x1/2 S-shaped open-end wrench, stamped on the face with "Armstrong" and "Made in U.S.A." with the Strong-Arm logo.

The overall length is 4.0 inches. The original finish was black paint, but most of the paint has been worn off.

This wrench is listed in the catalogs as a heavy-duty model for hex-head cap screws.


204-A 3/4 Single-Open Construction Wrench

[Armstrong 204-A 3/4 Single-Open Construction Wrench]
Fig. 13B. Armstrong 204-A 3/4 Single-Open Construction Wrench, with Inset for Reverse, ca. Mid 1940s to 1950s.

Fig. 13B shows an Armstrong 204-A 3/4 single-open construction wrench, stamped with the fractional size and model number followed by "Hardened" on the shank, and with the Strong-Arm logo forged into the shank. The reverse is marked with "Armstrong" and "U.S.A." forged into the shank.

The overall length is 11.4 inches, and the finish is plain steel.

This model was listed in the 1948 catalog as a "Hi-Ten" construction wrench.


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