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The Development of Lock-On Tools and Sockets

In the late 1920s Blackhawk worked intently on developing new methods for securing sockets to their drive tools. Their progress can be traced through a somewhat confusing series of overlapping patents filed around this time, and ultimately resulted in the "Lock-On" line of tools with locking studs and release buttons. To trace the development of the Lock-On products, it's helpful to look at the filing dates for the relevant patents, as several important patents were issued out of order with their filing.

  • The earliest related patent was #1,685,503, filed in 1927 and issued in 1928. It described a threaded locking stud that could be manually retracted when only a friction-ball coupling was needed.

  • Patent #1,896,645, the key patent for the Lock-On concept, was filed in 1929 but not issued until 1933. It describes a spring-loaded locking pin installed in the drive tools, together with a release button fitted in the sockets. Due to some technical problem, this patent was reissued in 1934 as patent #RE19,287, and this later patent number will be seen marked on many tools.

  • Patent #1,807,134 was filed in 1930 and describes a socket wrench drive plug fitted with two spring-loaded pins. This was intended as an improved push-through drive plug for female-drive ratchets, as the two pins retained the plug securely, but allowed it to be replaced easily if needed.

  • Patent #1,927,844 was filed on Jan. 27, 1932 and completed the important Lock-On patents. The key concept here was to place the locking pin at an angle, so that the pin could be automatically depressed by a socket pushed onto the drive stud. By avoiding the need to manually depress the lock pin, Lock-On tools became much more convenient to use, on par with the conventional friction-ball tools.

  • Patent #1,982,008 was filed on Feb. 23, 1934 and issued late that year, and offers a minor refinement to the Lock-On design. The patent describes the optimal Lock-On hole size in order to hold the socket tightly, and may be found marked on some of the sockets produced in the mid to late 1930s.

  • Patent #2,190,081, the last of the Lock-On patents, was filed in 1938 and issued in 1940. It describes an insertable sleeve used to retain the release button, as an alternative to crimping the outer opening. This was needed especially for sockets in the smaller sizes, as the thin walls of the drive end didn't have enough material to allow movement of the release button.

The series of patents show that the Lock-On ideas were developed in stages, and the corresponding products were offered in stages as well. The trademark records cite June 30, 1930 as the first commercial offering of Lock-On tools, and the 1930 catalog MG330 provides a snapshot of the products at this time. It shows the Lock-On tools with a spring-loaded pin, but the sockets do not yet have a release button; instead, the sockets have a hole to receive the pin, but a separate tool (a simple offset pin) was required to release the lock.

For some period of time Blackhawk sold both the conventional friction-ball tools (the "Quick Disconnect" or Q.D. line) as well as their new Lock-On tools, which were christened the "Chief" line. (Of course, the new Lock-On tools could have been called the "Slow Disconnect" line, but that didn't have the same marketing ring to it.) The Chief tools were apparently intended as a high-end or premium line and featured a polished chrome finish.

The 1930 catalog MG330 shows that both Q.D. and Chief product lines were available at that time, and Lock-On tools were offered in drive sizes 3/8, 1/2, and 3/4. (The 3/8-drive tools were in full sets only.) But once the socket release buttons and slanted locking pins were fully developed, Blackhawk made the bold (and risky) move of dropping their friction-ball tools, except for the smallest drive sizes where locking studs were impractical.

In the discussion that follows, we'll begin with the 1/2-drive Lock-On sockets, then examine the corresponding 1/2-drive tools. The other drive sizes will then be shown in later sections, as the development of these tools basically parallels the 1/2-drive case.


1/2-Drive Lock-On Sockets

The next few figures here will show some of the earliest examples of Lock-On sockets, tools that were produced before the first Lock-On patent was issued. These sockets all have a "Pat. Pend." notation, and the known dates of the patent filing allow a reasonable estimate of the production date. Since the key #1,896,645 patent hadn't been issued yet, the expected manufacturing date would fall within the range 1929-1933.

This estimated interval can be narrowed for certain model series, based on additional information about the sockets. Blackhawk catalogs for 1929 and 1930 show that the Lock-On tools were offered in stages, with only limited models available in 1929, significantly expanded offerings by early 1930, and still other models offered later.

The early Lock-On sockets did not include release buttons, even though the patent description shows sockets fitted with buttons. Instead, a small tool with a pin was needed to release the sockets from the drive stud.

Since release buttons were an important convenience feature, Blackhawk undoubtedly wanted to offer these as soon as possible, but apparently the manufacturing details took some time to resolve. As late as 1934 the Blackhawk catalog shows release buttons only on the larger 7/8-drive sockets, and presumably the smaller drive sizes were fitted in late 1934 or 1935.

Since the main Lock-On patents had been issued by 1933 (and the re-issue patent in 1934), and release buttons arrived in 1934 or later, we would expect to see the Lock-On patents marked on any socket with a release button. (Except perhaps for the 7/8-drive sockets, but these are rarely seen anyway.) Conversely, any socket with the Lock-On patents pending should not have a release button. (Earlier editions of this article had suggested that release buttons could have arrived by early 1932, but this is apparently not the case.)


Early 84xx Series 1/2-Drive 12-Point Sockets

We'll start the socket presentation with some of the earliest examples available, two 1/2-drive sockets in the 12-point 84xx series. Fig. 158 shows a Blackhawk model 8421 21/32 socket on the left, with a model 8424 3/4 socket on the right. Both are marked "U.S.A." and "Pat. Pend." but with no patent numbers, an indication of their early manufacturing date.

[Blackhawk 1/2-Drive 84xx Sockets]
Fig. 158. Blackhawk 1/2-Drive 84xx Sockets, with Inset for Drive Ends, ca. 1929-1933.

The sockets have a hole for the locking pin, but were not fitted with release buttons, as apparently the manufacturing details hadn't been worked out yet. The socket design includes a thin knurled band, providing continuity with the prior designs but mostly decorative in nature. The finish is polished chrome.

The 84xx sockets featured tapered walls and were the direct successors of the Dxx sockets in the Q.D. line; refer to an example of the Dxx sockets for comparison. The 84xx series was among the first group of Lock-On tools offered, and are listed in a 1929 Blackhawk Mechanic's Guide. The patent pending marking leads to an estimated manufacturing date in the range 1929-1933.

The inset in the photograph shows an important detail, the scalloped indentations machined into the drive ends. These indentations were intended to help depress the locking pin when attaching the socket to a drive stud, a convenience feature when using Lock-On tools. Such indentations would not have been needed once the slanted locking pins of patent #1,927,844 were in use, but even after switching to the slanted pins, the indentations in the sockets provided backwards compatibility for owners of the older drive tools.


Early 8432 1/2-Drive 12-Point Socket

[Blackhawk 1/2-Drive 8432 Socket]
Fig. 159. Blackhawk 1/2-Drive 8432 Socket, with Insets for Drive End and Broaching, ca. 1929-1933.

Fig. 159 shows another early example of the 84xx series in greater detail, a Blackhawk model 8432 socket marked "Pat. Pend." on the base.

This example has the tapered walls and knurled band seen in the previous figure, but as a larger-sized socket has a reduced base.

The left inset shows the drive end with the scalloped indentations discussed in the previous figure. The hole for the locking pin appears at the front of the socket.


8928 1/2-Drive Deep Socket

[Blackhawk Early 1/2-Drive 8928 Deep Socket]
Fig. 160. Blackhawk Early 1/2-Drive 8928 Deep Socket, ca. 1930-1933.

Fig. 160 shows another early Lock-On socket, a 1/2-drive model 8928 7/8 deep socket with a cross-bar hole. The socket is marked "U.S.A." with "Pat. Pend.", again indicating an early manufacturing date. Another marking states "Use for Spark Plugs Only", providing the intended application.

The drive end of the socket includes the scalloped indentations discussed with the previous example, to assist with inserting the drive stud. The socket also includes a thin knurled band around the base, a decorative feature providing continuity with earlier designs.

This socket includes a cross-bar hole, a common feature for spark-plug sockets at the time. The cross-bar holes apparently served double-duty for the Lock-On pin as well, as there is no separate hole for the pin. (And obviously, no release button either.)

The model 8928 socket was not yet listed in the 1930 MG330 catalog, so the patent pending status suggests that a manufacturing date of late 1930 to 1933 is probably reasonable.


Early 66xx Series 1/2-Drive Sockets

[Blackhawk Early 1/2-Drive 66xx Series Sockets]
Fig. 161. Blackhawk Early 1/2-Drive 66xx Series Sockets, with Inset for Drive Ends, ca. 1930-1933.

Fig. 161 shows several examples of early Lock-On sockets in the 1/2-drive 66xx series, which featured thin straight walls and 12-point broachings. The sockets are all marked "U.S.A." and "Pat. Pend.", but with no patent numbers, indicating an early manufacturing date.

The model numbers and sizes are, from the left, model 6614 (7/16), 6625 (25/32), and 6626 (13/16).

These sockets have a hole for the locking pin, but were not fitted with release buttons. The socket design includes a thin knurled band, mostly decorative in nature, and likely a carry-over from the earlier functional knurling used for gripping the socket.

The 66xx series sockets are not listed in the MG330 catalog of 1930. Together with the patent pending status, this leads to an estimated manufacturing date in the range of late 1930 to 1933.

The inset to the photograph shows the drive ends with scalloped indentations, a feature intended to help depress the locking pin, as was discussed above. Blackhawk sockets retained these indentations through the life of the 66xx series and into the early successor 401xx series, as the later figures below will show. The presence of the indentations will assist in identifying early examples of the later socket series, as will be seen shortly.


Later 8432 1/2-Drive 12-Point Socket

[Blackhawk 8432 1/2-Drive Socket]
Fig. 162. Blackhawk 1/2-Drive Model 8432 1 Inch Socket, with Inset for Drive End, ca. 1934-1938.

In Fig. 162 we see a later 1/2-drive socket in the 84xx series, the Blackhawk model 8432 1 inch socket. The socket is marked "Made in U.S.A." with patents "U.S. Pat's 1,927,844 RE.19,287 1,982,008".

This socket is comparable to the earlier 84xx sockets shown above. The finish is polished chrome, and the socket design includes the thin knurled band seen in the previous figures.

A few comments are in order regarding the patent numbers, as this is our first socket example to be marked with these patents. The re-issue patent #RE19,287 refers to the same claims as patent #1,896,645, the key Lock-On patent, and corrected some technical problem in the original filing. Although about a year elapsed between the issue of patents #1,896,645 and #RE19,287, no tools have been found marked with the former number.

The patent #1,927,844 defined the use of a slanting drive stud and so, strictly speaking, shouldn't apply to sockets; however, Blackhawk always listed patents #1,927,844 and #RE19,287 together. Finally, the patent #1,982,008 noted here seems to have been marked only for a limited time, on sockets from the mid to late 1930s.


Later 66xx Series 1/2-Drive Sockets

[Blackhawk 66xx 1/2-Drive Lock-On Sockets]
Fig. 163. Blackhawk 1/2-Drive 66xx Series Sockets, with Inset for Drive Ends, ca. 1934-1937.

Fig. 163 shows another group of the 1/2-drive 66xx series Lock-On sockets, but produced at a later date, after the patent numbers were available. The sockets are marked "Made in U.S.A." with "U.S. Pats. 1927844 RE19287 1982008"; note the presence of the #1,982,008 patent, issued in late 1934.

The models and sizes are, from the left, 6621 (21/32), 6628 (7/8), and 6630 (15/16). The inset shows the drive end indentations, similar to the previous figure.

The patent number markings on these sockets place the date of manufacture some time after late 1934. At this time all Lock-On sockets were being fitted with release buttons, as shown in the figure. (The lefthand socket has lost its button.)

Around 1938 or so, Blackhawk phased out the 66xx series sockets in favor of the 401xx series, a line with basically the same specifications but a slightly different design.


8124 1/2-Drive 8-Point Socket

[Blackhawk 8124 1/2-Drive Socket]
Fig. 164. Blackhawk 8124 1/2-Drive 3/4 8-Point Socket, ca. 1934-1938.

Fig. 164 shows another 1/2-drive Lock-On socket from the 81xx 8-point series, the Blackhawk model 8124 3/4 socket. The socket is marked "U.S. Pats. RE19287 1,927,844", the usual Lock-On patents, but also shows patent #1,982,008.

This socket also has the thin knurled band as seen in the previous figures.


1/2-Drive Lock-On Tools

We've now seen a number of examples of the Lock-On sockets, so it's time to look at the corresponding drive tools. We'll begin with several early examples fitted with the original (non-slanted) Lock-On pins, and marked with a "Pat. Pend." notation. These tools were produced while the Lock-On designs were still being developed, and have a manufacturing date in the range 1929-1932.


9004 Release Tool

Although the early Lock-on patent included the provision for a release button on each socket, Blackhawk didn't begin fitting release buttons on sockets until some years after the introduction of the Lock-on line. Hence the need for the tool in this next figure.

[Blackhawk 9004 Release Tool]
Fig. 165. Blackhawk 9004 Release Tool, with Insets for Side View and Reverse Detail, ca. 1929-1934.

Fig. 165 shows a Blackhawk 9004 release tool, consisting of a forged handle with short and long tapered pins on the end. The handle is marked with "9004" and "USA" forged into on side, with "Blackhawk" on the reverse.

The overall length is 4.2 inches, and the finish is cadmium plating.

This tool was designed to depress the locking pin on a drive stud to allow removal of the socket or tool. Since the need for a separate tool to remove sockets was somewhat inconvenient, the later generation of Lock-on sockets were equipped with a release button.


Early 9201 1/2-Drive Offset Handle

[Blackhawk 9201 1/2-Drive Offset Handle]
Fig. 166. Blackhawk 9204 1/2-Drive Offset Handle, with Inset for Top View and Marking Detail, ca. 1929-1932.

Fig. 166 shows an early 1/2-drive Blackhawk 9201 breaker bar, stamped "Pat. Pend." on the shank.

The overall length is 10.6 inches, and the finish is chrome plating.

The patent pending notation refers to patent #1,896,645, and based on the patent filing date, this tool was likely made in 1929-1932.

This tool is constructed of a solid bar shank with the drive head pressed on the end and secured by a pin.

The Model 9201 breaker bar is listed in the 1929 Blackhawk Mechanic's Guide catalog, placing this model among the first Lock-On tools to be offered by Blackhawk.


Early 9204 1/2-Drive Sliding Tee Handle

[Blackhawk 9204 1/2-Drive Sliding Tee Handle]
Fig. 167. Blackhawk 9204 1/2-Drive Sliding Tee Handle, with Inset for Marking Detail, ca. 1929-1932.

Fig. 167 shows a 1/2-drive Blackhawk 9204 sliding Tee handle, stamped "Pat. Pend." and "U.S.A." on the bar.

The overall length is 11.0 inches, and the finish is chrome plating.

The patent pending notation refers to patent #1,896,645, and based on the patent filing date, this tool was likely made in 1929-1932.

The Model 9204 sliding Tee was among the first Lock-On tools offered by Blackhawk, and this model is listed in the 1929 Blackhawk Mechanic's Guide catalog.


Early 9210 1/2-Drive 10-Inch Rotating-Grip Extension

[Blackhawk 9210 10 Inch Rotating-Grip Extension]
Fig. 168. Blackhawk 9210 1/2-Drive 10 Inch Rotating-Grip Extension, ca. 1929-1932.

Fig. 168 shows an early Blackhawk model 9210 10 inch rotating-grip extension, marked with a "Pat. Pend." notation.

The overall length is 10.0 inches.

As this is a first-generation Lock-On tool with a non-slanted locking pin, the patent pending notation refers to patent #1,896,645. Based on the patent filing date, this tool was likely made in 1929-1932.

The Model 9210 extension is listed in the 1929 Blackhawk Mechanic's Guide catalog, making it among the first Lock-On tools offered. Note that the rotating grip has a knurled surface, the handle style used from the late 1920s until sometime in the 1930s.


Early 9260 1/2-Drive 10 Inch Extension

[Blackhawk 9260 10 Inch Extension]
Fig. 169. Blackhawk 9260 1/2-Drive 10 Inch Extension, with Insets for Construction and Marking Detail, ca. 1929-1932.

Fig. 169 shows an early Blackhawk 9260 10 inch extension in the plain style, stamped "Pat. Pend." and "U.S.A.", faintly visible in the upper composite inset.

The overall length is 10.0 inches, and the finish is chrome plating.

The drive head is equipped with a cross-bar hole for a 9/16 diameter bar, and a detent ball is provided to hold the bar in place.

This is a first-generation Lock-On tool with the locking pin perpendicular to the drive stud, although a former owner has ground the top of the pin to provide a slanted surface. The patent pending notation refers to patent #1,896,645, and based on the patent filing date, this extension was likely made in 1929-1932.


Early 9506 1/2-Drive 16 Inch Brace

[Blackhawk 1/2-Drive 9506 16 Inch Brace]
Fig. 170. Blackhawk 1/2-Drive 9506 16 Inch Brace, with Insets for Detail, ca. 1929-1932.

Fig. 170 shows a 1/2-drive Blackhawk 9506 16 inch brace or speeder, marked with a "Pat. Pend." notation.

The overall length of 16.2 inches and the throw is 4.7 inches. The finish is a thin chrome plating, now worn through in some areas.

The brace is equipped with a rotating knurled hand grip as well as a knurled end piece.


Early 9611 1/2-Drive 19 Inch Speeder

[Blackhawk 9611 1/2-Drive 19 Inch Speeder]
Fig. 171. Blackhawk 9611 1/2-Drive 19 Inch Speeder, with Inset for Detail, ca. 1929-1932.

Fig. 171 shows a 1/2-drive Blackhawk 9611 19 inch speeder, marked with a "Pat. Pend." notation.

The overall length of 19.4 inches and the throw is 4.7 inches.

The model 9611 speeder was among the first Lock-On tools and is listed in the 1929 Blackhawk Mechanic's Guide catalog.

The knob on this tool is a replacement for the original, though rather nicely done with polished wood (walnut) for the end. The original knob was a patented design described by patent #1,764,690, and an example can be seen in a later figure for the 49994 speeder. (The 1929 catalog promised the knob to be "practically indestructible".)


9811 1/2-Drive Ratchet

[Blackhawk 9811 Ratchet]
Fig. 172. Blackhawk 9811 1/2-Drive Ratchet, with Inset for Side View, ca. 1929-1932.

Fig. 172 shows a 1/2-drive Blackhawk 9811 ratchet, stamped "Made in U.S.A." in the recessed panel of the handle.

The overall length is 10.0 inches, and the finish is plain steel.

The 9811 ratchet was intended for use with a model 9802 drive plug, illustrated in the next figure. The drive gear of the ratchet includes a groove to engage the locking pins of the plug, visible in the photograph at the left. A barrier in the center of the groove prevents the plug from being pushed all the way through.

The 9811 ratchet was among the first Lock-On tools offered in 1929. This model was essentially the same as the earlier Q.D. Model 911X Ratchet, but used a modified drive gear to fit the 9802 Lock-On drive plug. This particular example has a 14-tooth drive gear, a relatively coarse mechanism used in the earlier models.

By 1934 the 9811 ratchet was being offered with a reversing lever, and was later superseded by the Model 49977 Ratchet shown later in this article.


Early 9802 1/2-Drive Drive Plug for 9811 Ratchet

[Blackhawk 9802 1/2-Drive Drive Plug]
Fig. 173. Blackhawk 9802 1/2-Drive Drive Plug, ca. 1930-1931.

Fig. 173 shows a 1/2-drive Blackhawk 9802 drive plug, marked "U.S.A." with a "Pat. Pend." notation. The overall length is 1.4 inches.

The pending status here refers to patent #1,807,134, filed by E.M. Pfauser in 1930 and issued in 1931. The two locking pins are used to keep the drive plug captive in the ratchet drive gear, while also allowing for an easy replacement in the case of breakage. Note that the locking pins are also backed by conventional detent balls, perhaps for a better holding grip.


9810 1/2-Drive "Free Wheeling" Ratchet

One of the Blackhawk's most notable innovations in drive tools was their development of a practical mechanism for a reversible gearless ratchet. The gearless designs were developed and patented beginning in 1931 with patent #1,936,640, issued in 1933. A later improvement was made with patent #2,003,155, filed in 1932 and issued in 1935.

Blackhawk coined the term "Free Wheeling" to describe the gearless ratchets, and although they claimed to have registered a trademark on the name, no registration has been found in the USPTO database. The gearless ratchets were first offered as the 1/2-drive model 9810, probably in the early 1930s. Later models were available in both 3/8-drive and 1/2-drive.

[Blackhawk 9810 1/2-Drive Free Wheeling Ratchet]
Fig. 174. Blackhawk 9810 1/2-Drive "Free Wheeling" Ratchet, with Insets for Side View and Marking Detail, ca. 1933-1935.

Fig. 174 shows an early 1/2-drive Blackhawk 9810 "Free Wheeling" gearless ratchet, stamped "Made in U.S.A." with "Pat. No. 1936640" and "Other Pats. Pend." on the shank, with the model number and "Free Wheeling Ratchet" on the reverse.

The overall length is 10.5 inches, and the finish is chrome plating.

The patent notice refers to patent #1,936,640, filed by E.M. Pfauser in 1931 and issued in 1933. The pending status probably refers to patent #2,003,155, an improvement on the gearless design issued in 1935. Based on the patent markings, this ratchet was likely made in 1933-1935.

Later versions of the gearless ratchets can be seen as the Blackhawk 49997 1/2-Drive Gearless Ratchet and Blackhawk 34981 3/8-Drive Gearless Ratchet.


Early 8502 1/2-Drive Universal

[Blackhawk 1/2-Drive 8502 Universal]
Fig. 175. Blackhawk 1/2-Drive 8502 1/2-Drive Universal, ca. 1929-1932.

Fig. 175 shows an early 1/2-drive Blackhawk model 8502 universal, marked "U.S.A." with a "Pat. Pend." notation. The overall length is 2.8 inches.

The finish is polished chrome, although worn through in many areas. The markings on this tool were too faint to show well in the photograph, as the surface is worn apparently from rolling around in a toolbox.

The 8502 universal was among the first Lock-On tools offered, and is listed in the 1929 Blackhawk Mechanic's Guide catalog. This tool is fitted with the original Lock-On drive stud, perpendicular to the surface rather than slanted. To assist with inserting the drive studs, early Lock-On sockets (and drive tools) were made with indentations in the drive end, to help depress the locking pin.


Early 9202 1/2-Drive 11 Inch Offset Handle

[Blackhawk 9202 1/2-Drive 11 Inch Offset Handle]
Fig. 176. Blackhawk 9202 1/2-Drive 11 Inch Offset Handle, ca. 1930-1932.

Fig. 176 shows a 1/2-drive Blackhawk 9202 11 inch offset handle with a distinctive head style, stamped "Made in U.S.A." with a "Pat. Pend." notice.

The overall length is 11.1 inches. The original finish was chrome plating, but most of the finish has been lost to wear and rust.

This is a first-generation Lock-On tool with a non-slanted locking pin, and the patent pending notice refers to patent #1,896,645.

The 9202 breaker bar was not listed in the 1929 Blackhawk Mechanic's Guide, but was offered in the 1930 MG330 catalog. Based on the patent date and catalog information, this tool was likely made in 1930-1932.


Early 9207 1/2-Drive 11 Inch Flex-Head Handle

[Blackhawk 9207 1/2-Drive 11 Inch Flex-Head Handle]
Fig. 177. Blackhawk 9207 1/2-Drive 11 Inch Flex-Head Handle, ca. 1930-1932.

Fig. 177 shows a 1/2-drive Blackhawk 9207 11 inch flex-head handle, marked "Made in U.S.A." with a "Pat. Pend." notice. The knurled handle has a cross-bar hole with a detent ball, allowing for convenient usage as a Tee handle.

The overall length is 11.7 inches, and the finish is chrome plate.

The model 9207 breaker bar was not listed in the 1929 Blackhawk Mechanic's Guide, but was included in their 1930 MG330 catalog, where it is referred to as a "Hinged Offset Handle". As a first-generation Lock-On tool with a non-slanted locking pin, the patent pending notice refers to patent #1,896,645. Based on the patent date and catalog information, this tool was likely made in 1930-1932.


Early 9208 1/2-Drive 15 Inch Flex-Head Handle

[Blackhawk 9208 1/2-Drive 15 Inch Flex-Head Handle]
Fig. 178. Blackhawk 9208 1/2-Drive 15 Inch Flex-Head Handle, with Insets for Marking and Construction Detail, ca. 1930-1932.

Fig. 178 shows a similar but longer model, the 1/2-drive Blackhawk 9208 15 inch flex-head handle. The shank is stamped "Made in U.S.A." with a "Pat. Pend." notice, and the knurled handle has a cross-bar hole with a detent ball (see insets).

The overall length is 15.7 inches. The original finish was chrome plating, but virtually all of the plating has been lost due to extensive wear.

As with the Blackhawk 9207 shown in a previous figure, this model was not listed in the 1929 Blackhawk Mechanic's Guide, but was included in their 1930 MG330 catalog. The patent pending notice refers to patent #1,896,645, which together with the catalog information indicates production in the range 1930-1932.

That completes our look at the Lock-On tools produced before the basic patents were issued. For the remainder of this section, we'll look at examples marked with the Lock-On patents.


9206 1/2-Drive 6 Inch Rotating-Grip Extension

[Blackhawk 9206 1/2-Drive 6 Inch Rotating-Grip Extension]
Fig. 179. Blackhawk 9206 1/2-Drive 6 Inch Rotating-Grip Extension, with Insets for Construction and Marking Detail, ca. 1934-1936.

Fig. 179 shows a 1/2-drive Blackhawk 9206 6 inch extension with a knurled rotating grip, stamped "Blackhawk" and "Made in U.S.A." with a "U.S. Pats. 1,927,844 RE.19,287 1,982,008" patent notice.

The overall length is 6.0 inches, and the finish is chrome plating with losses due to wear.

The upper right inset shows the construction details of the drive end. Note that the cross-bar hole is fitted with a detent ball to help secure the bar when in use, a convenience feature sometimes missing from modern tools. Note also that the drive opening has indentations on all four sides, a convenience when using older tools without the slanted locking pin.

The Model 9206 rotating-grip extension was among the first Lock-On tools offered by Blackhawk, and this model is listed in the 1929 Blackhawk Mechanic's Guide catalog. This particular tool dates from a few years later though, as the patent markings indicate production in 1934 or later.


17TD 1/2-Drive Lock-On Socket Set

The Blackhawk 17TD socket set is a modest collection of early 1/2-drive tools and sockets. The set consists of a 9217 flex-head handle, 9209 cross-bar, 9004 release tool, and 14 84xx series (straight-wall) sockets. As this is a relatively early set, the sockets are not fitted with release buttons and a special release tool is provided to facilitate removing the sockets.

The socket models and sizes are 8412 (3/8), 8414 (7/16), 8416 (1/2), 8418 (9/16), 8419 (19/32), 8420 (5/8), 8422 (11/16), 8424 (3/4), 8426 (13/16), 8428 (7/8), 8430 (15/16), 8432 (1 Inch), 8434 (1-1/16), and 8436 (1-1/8).

Our 17TD set is currently being prepared for display, and photographs will be added in the near future.

Fig. 180. Blackhawk 1/2-Drive 17TD Lock-On Socket Set To Be Added.

3/8-Drive Socket and Tools

Although Blackhawk had originally planned to offer a full range of features for its 3/8-drive Lock-On tools, the sockets in particular turned out to be too small for release buttons. Blackhawk responded by designing the intermediate 7/16-drive Lock-On tools, and provided 7/16-drive sockets covering almost the same range as the 3/8-drive and 1/2-drive sizes combined.

Blackhawk continued to produce the 3/8-drive Lock-On tools for a number of years, but without the convenience of the built-in release buttons. As these tools are seldom found, we can assume that only a relatively small numbers of the 3/8-drive Lock-On tools were sold, probably because of the inconvenience of the manual release.

Eventually Blackhawk recognized that 3/8-drive didn't really need the Lock-On feature, and 3/8-drive tools went back to using detent balls. A few examples of these can be seen in a section on Later 3/8-Drive Tools.


7810S 3/8-Drive 12-Point Socket

[Blackhawk 3/8-Drive 7810S Socket]
Fig. 181. Blackhawk 3/8-Drive 7810S 5/16 Socket, with Inset for Drive End, ca. 1930-1933.

Fig. 181 shows another early example of a Lock-On socket, a Blackhawk 7810S 5/16 socket marked "U.S.A." and "Pat. Pend." but with no patent numbers.

As was the case for the previous figure, this socket has a hole for the locking pin, but was not fitted with a release button. The socket design includes a thin knurled band, mostly decorative in nature, and the finish is polished chrome.

The 78xx series sockets are not listed in a 1929 Blackhawk catalog, but are listed (without release buttons) in the MG330 catalog of early 1930. Together with the patent pending status, this leads to an estimated manufacturing date in the range 1930-1933.

The inset shows the scalloped indentations machined into the drive end, as discussed in the prior figure.


9207S 3/8-Drive Lock-On 8 Inch Flex-Head Handle

[Blackhawk 9207S 3/8-Drive 8 Inch Flex-Head Handle]
Fig. 182. Blackhawk 9207S 3/8-Drive Lock-On 8 Inch Flex-Head Handle, with Inset for Marking Detail, ca. 1930-1932.

Fig. 182 shows an early 3/8-drive Blackhawk 9207S 8 inch flex-head handle with a first-generation locking pin, stamped "Pat. Pend." and "U.S.A." on the shank. The knurled handle is equipped with a cross-bar hole, with a detent ball added to help hold the bar in place.

The overall length is 8.0 inches, and the finish is chrome plating.

At first glance this tool might appear to have a slanted locking pin, due to a minor modification by a former owner to give the pin a sloping top. (If the pin is rotated, the orientation of the slope follows the rotation.)

The 9207S handle was not listed in the 1929 Blackhawk Mechanic's Guide, but was included in their 1930 MG330 catalog, where it is referred to as a "Hinged Offset Handle". As a first-generation Lock-On tool with a non-slanted locking pin, the patent pending notice refers to patent #1,896,645. Based on the patent date and catalog information, this tool was likely made in 1930-1932.


9209S Handle Bar for 3/8-Drive Tools

[Blackhawk 9209S Handle Bar for 3/8-Drive Tools]
Fig. 183. Blackhawk 9209S Handle Bar for 3/8-Drive Tools, with Inset for Marking Detail, ca. 1930-1937.

Fig. 183 shows a Blackhawk 9209S handle bar for use with 3/8-drive tools, stamped "Made in U.S.A." on the shank. The handle bar has a shallow groove in the center and a stop-ball at one end.

The overall length is 7.0 inches, and the finish is chrome plating, with extensive losses due to wear.

The 9209S bar was designed to form an Ell handle or sliding Tee handle with tools such as the 9207S Flex-Head Handle or 9210S Extension.


9210S 3/8-Drive 10 Inch Lock-On Extension

[Blackhawk 9210S 3/8-Drive 10 Inch Lock-On Extension]
Fig. 184. Blackhawk 9210S 3/8-Drive 10 Inch Lock-On Extension, ca. 1934-1937.

Fig. 184 shows a 3/8-drive Blackhawk 9210S 10 inch extension, marked "Made in U.S.A." with the "U.S. Pats. 1,927,844 RE19,287 1,982,008" patent notice.

The overall length is 10.0 inches.

The extension is equipped with a slanted locking pin, and the driven end has a cross-bar hole (with a detent ball) for use as a Tee-handle.


9510S 3/8-Drive Lock-On 18 Inch Speeder

[Blackhawk 9510S 3/8-Drive 18 Inch Speeder]
Fig. 185. Blackhawk 9510S 3/8-Drive Lock-On 18 Inch Speeder, with Inset for Marking Detail, ca. 1932-1934.

Fig. 185 shows a 3/8-drive Blackhawk 9510S 18 inch speeder, stamped "Pat. Pend." and "U.S.A." on the shank.

The overall length is 18.1 inches, and the finish is chrome plating, with losses due to wear and rust.

This speeder is fitted with a slanted locking pin.


3/4-Drive Sockets and Tools

Blackhawk had offered 3/4-drive tools during the mid 1920s as part of its Q.D. product line, and by 1930 Blackhawk was offering 3/4-drive tools in the Lock-On series as well.

The model numbers for the initial 3/4-drive Lock-On tools were derived by appending an "N" (perhaps for "New") to the older Q.D. numbers, at least where the tools were otherwise comparable. These numbers were a bit confusing though, and sometime in the mid 1930s Blackhawk revamped their model numbers, assigning a 6xxxx series to the 3/4 drive size.


Early D46XN 3/4-Drive 1-7/16 Socket

Our first example for the 3/4-drive sockets is unusually significant, in that it shows an early patent-pending Lock-On socket with apparent hot-broached construction.

[Blackhawk 3/4-Drive D46XN 1-7/16 Socket]
Fig. 186. Blackhawk 3/4-Drive D46XN 1-7/16 Socket, with Panels for Drive End and Broaching, ca. 1930-1933.

Fig. 186 shows a 3/4-drive 12-point Blackhawk D46XN 1-7/16 socket, marked "U.S.A." and with a "Pat. Pend." notation. The photograph has been arranged as a triptych, with the full view in the center, flanked by the drive end on the left and the broached end on the right.

The 3/4-drive DxxXN socket series was the double-hex continuation of the xxXN models. The DxxXN sockets were not listed in the 330MG catalog of 1930, so these models were probably introduced sometime in late 1930 or 1931. Together with the patent pending status, this leads to an estimated manufacturing date in the range of late 1930 to 1933.

The drive end shown in the left panel has the scalloped indentations seen on other early Lock-On sockets, and the hole for the locking pin (with no release button) is visible at the front.

The most notable aspects of this socket concern the construction techniques, in particular the broaching and contour grinding. A careful examination of the broached area shows only smooth walls with no trace of chatter marks, indicating the use of a hot-broaching process. The residual material from the broaching has been carefully clipped against the walls, apparently by a second trimming or boring operation.

This is a significant finding, as it makes Blackhawk possibly the first tool company to use hot-broached (or hot-forged) construction for its sockets. (An advertising blurb in the 1941 catalog makes this claim, but provided no details.) Hot-broaching was an important development for socket technology, and this reinforces Blackhawk's status as an innovator. Other companies were not far behind though; Snap-On may have done some hot-broaching as early as 1934, and Duro Metal Products filed its important hot-broach patent #2,027,922 in 1935.


D60XN 3/4-Drive 1-7/8 Socket with Patent Numbers

[Blackhawk 3/4-Drive D60XN 1-7/8 Socket]
Fig. 187. Blackhawk 3/4-Drive D60XN 1-7/8 Socket, with Insets for Drive End and Broaching, ca. 1934-1935.

Fig. 187 shows a 3/4-drive Blackhawk D60XN 1-7/8 socket, marked "Made in U.S.A." with a "U.S. Pats. 1927844 RE.19287 1982008" patent notice.


T4XN 3/4-Drive 18 Inch Sliding Tee Handle

The next several figures show examples of early 3/4-drive Lock-On tools, dating from around the same time as sockets in the previous two figures.

[Blackhawk T4Xn 3/4-Drive 18 Inch Sliding Tee Handle]
Fig. 188. Blackhawk T4XN 3/4-Drive 18 Inch Sliding Tee Handle, with Inset for Marking Detail, ca. 1930-1932.

Fig. 188 shows an early 3/4-drive Blackhawk T4XN 18 inch sliding Tee handle, marked "U.S.A." with a "Pat. Pend." patent notice.

The overall length is 18.0 inches, and the finish is chrome plating.

The drive stud is fitted with a non-slanted locking pin, making this example one of the first generation of Lock-On tools. The patent pending notation refers to the early Lock-On patent #1,896,645, filed in 1929 and issued in 1932.

The T4XN breaker bar was designed to work as a T-handle with other extensions, so the bar has a stop ball at only one end. The bar has a diameter of 13/16 inches, the same size as used by Snap-On tools.

An earlier version of this model (before the Lock-On feature) can be seen as the Blackhawk T4X 3/4-Drive Sliding Tee Handle.


T8XN 3/4-Drive 8 Inch Extension

[Blackhawk T8Xn 3/4-Drive 8 Inch Extension]
Fig. 189. Blackhawk T8XN 3/4-Drive 8 Inch Extension, with Inset for Construction Detail, ca. 1932-1934.

Fig. 189 shows a 3/4-drive Blackhawk T8XN 8 inch Lock-On extension, marked "U.S.A." with a "Pat. Pend." patent notice.

The overall length is 8.5 inches, and the finish is chrome plating.

The drive stud is equipped with a slanted locking pin for easy insertion, but the drive end does not include a release button. The patent pending status refers to patent #1,927,844, issued in 1933 and describing the slanted locking pin seen here.

The drive head includes a cross-bar hole with a detent ball, allowing use as a T-handle as well. The standard cross-bar was the Blackhawk Model T4XN shown above, which had a diameter of 13/16 inches and a length of 18 inches. Note that this 13/16 diameter is the same as that used by Snap-On for their 3/4-drive tools, allowing the Blackhawk and Snap-On tools to be used interchangeably.


916N 3/4-Drive Ratchet with T113XN Drive Plug

[Blackhawk 916N 3/4-Drive Ratchet]
Fig. 190A. Blackhawk 916N 3/4-Drive Ratchet, with Inset for Side View, ca. 1932-1934.

Fig. 190A shows a 3/4-drive Blackhawk 916N ratchet with a forged flat handle, marked "Blackhawk Mfg. Co." and "Milwaukee Wis. Made in U.S.A." in forged raised letters. The face plate is stamped with the model number and a "Patents Pend." notice.

The overall length is 16.0 inches. and the finish is chrome plating with polished faces.

The ratchet mechanism uses a 16-tooth gear, the same as in the very similar Q.D. predecessor Blackhawk 916 Q.D. Ratchet. The main difference between the two models is the use of a drive opening with slots on two adjacent faces, to accept the locking pins of the T113XN drive plug.

The model 916N ratchet was offered as early as 1930, but this particular example is probably from 1932 or later, as the T113XN drive plug has slanted locking pins.


T113XN 3/4-Drive Ratchet Plug

[Blackhawk T113XN 3/4-Drive Ratchet Plug]
Fig. 190B. Blackhawk T113XN 3/4-Drive Ratchet Plug, ca. 1932-1934.

Fig. 190B shows a 3/4-drive Blackhawk T113XN ratchet plug, marked "Pat. Pend." and "U.S.A." on the side.

The overall length is 1.8 inches. and the finish is chrome plating.

This drive plug is fitted with slanted locking pins, suggesting production in 1932 or later. The patent pending status refers to patent #1,927,844, issued in 1933 and describing the slanted locking pin seen here.


7/8-Drive Tools

During the 1920s and early 1930s Blackhawk's largest drive size was 7/8-drive. Production of this size continued into the mid 1930s, but was superseded by 1 inch drive and discontinued sometime after 1935. The 7/8-drive size was still listed in a 1935 catalog, but a price list from April of 1937 shows only the 1 inch drive size.


D56XX 7/8-Drive 1-3/4 Socket with Release Button

According to the 1934 Blackhawk catalog MG534, release buttons were available at that time, but only for the 7/8-drive sockets. This next figure shows an example.

[Blackhawk 7/8-Drive D56XX 1-3/4 Socket]
Fig. 191. Blackhawk 7/8-Drive D56XX 1-3/4 Socket, with Insets for Broaching and Marking Detail, ca. 1934-1938.

Fig. 191 shows a 7/8-drive Blackhawk D56XX 1-3/4 socket with a release button, marked "Made in U.S.A." with a "U.S. Pats. 1927844 RE.19287 1982008" patent notice.

In this socket we see the long-awaited release button for the first time. The button consists of a plunger with an expanded ring, and is installed in a stepped hole. After the plunger was installed in the hole, the outer opening was crimped to capture the button, similar to the way friction balls were installed.

The patent notice is the same as that in the previous figure.


920 7/8-Drive Ratchet

[Blackhawk 920 7/8-Drive Ratchet]
Fig. 192. Blackhawk 920 7/8-Drive Ratchet, ca. 1930-1934.

Fig. 192 shows a Blackhawk 920 7/8-drive ratchet with a heavy forged flat handle. The handle is marked "Blackhawk Mfg. Co." with "Milwaukee, Wis." and "Made in U.S.A." in forged raised letters.

The overall length is 20.0 inches, and the finish is cadmium plating.

The ratchet mechanism uses a 16-tooth drive gear, and the drive opening has a slot for use with a model T13XX Lock-On drive plug.


T9XX 3/4-Drive To 7/8-Drive Adapter

[Blackhawk T9XX 3/4-Drive To 7/8-Drive Adapter]
Fig. 193. Blackhawk T9XX 3/4-Drive To 7/8-Drive Adapter, ca. 1932-1934.

Fig. 193 shows a Blackhawk T9XX 3/4-drive to 7/8-drive adapter, marked "U.S.A." with a "Pat. Pend." notation.

The overall length is 2.2 inches, and the finish is cadmium plating.

The pending status refers to patent #1,927,844, issued in 1933. The patent describes the use of a slanted locking pin, as seen in the photograph here.


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