Tank Helmet M-1938 & Related Equipment
Two basic tanker helmet designs had been in use through the mid 1930’s. One of these had been developed by the Infantry, and the other one by the Cavalry. The basic purpose of both helmets in tank applications was to offer the tankler some protection from frequent bumps against the tank's interior. However, it was becoming increasingly apparent that neither of these helmets offered optimal protection as tanks were becoming faster, more agile, and more compact. In addition, the continued use of two different helmets added unnecessary cost and complexity within the Army supply chain.
In 1938, the Ordnance Board initiated design work that would set a single standard for a new and improved tank helmet. The Board tested the two existing military varieties, along with several commercial models. Based on their tests, the Ordnance Board decided that the Cavalry helmet provided the best design foundation, and successfully encouraged the Rawlings Manufacturing Company to optimize the design. Rawlings was an obvious choice, since they were the premier manufacturer of football helmets at that time.
A three-person design team at Rawlings headed up this project, and on 1 May 1941 they filed a patent for what was simply called a "Tank Helmet." Much later, this style of tank helmet was designated "M-1938" in reference to the year of the initiation of the project. This alpha-numeric designator does not commonly appear in wartime documentation.
As stated in the patent application, the primary design objectives of the Tank Helmet were to provide:
Note that ballistic protection was not part of the original design criteria, apparently because it was felt that this would slow the availability of a helmet that at least offered enhanced bump protection.
As expected, the new Rawlings helmet resembled a football helmet in its design and construction. The outer crown and rear neck guard shells were constructed of a durable fiber resin, similar to the earlier tank helmets. The interior of the helmet featured a suspension system consisting of felt pads, leather pad retainers, and waxed cotton cords. This suspension system held the helmet in proper position on the wearer’s head and absorbed much of the shock when a bump was encountered.
Drawings from Rawlings Patent Filed 1 May 1941
The most distinctive new feature of the M-1938 tanker helmet relative to the previous versions was the leather ear flap assembly. The ear flap extended well below the wearer’s ear and contained an ingenious flexible housing for retaining the ear phones in their proper position. The ear phones fit into a slot in the leather flap, and a thin leather fastening piece snapped over the ear phone to hold it in place. This leather fastening piece could be adjusted forward or backward via three metal snap fasteners to position the ear phone directly over the user’s ears. A curved leather-covered metal spring arm extended downward from the helmet’s fiber shell and exerted tension on the ear phone to hold the ear flap assembly snugly against the user’s ear. The spring arm was mounted on a swivel to allow it to be placed in a variety of positions, depending upon the user’s needs and accessory equipment.
The ear flaps were also secured in place on the lower edges by an elasticized strap that connected through the rear fiber neck guard to fasteners at the bottom of each ear flap. The ear flaps fit snugly but comfortably, and without the use of chin straps, the helmet could be put on or taken off very easily.
M-1938 tank helmets were introduced to the Armored Corps in 1941, even though the patent was not technically accepted until 12 May 1942. Manufacturing rights were granted to Rawlings Manufacturing Corporation, Sears Saddlery Company, Wilson Athletic Goods Manufacturing Company, and A.G. Spaulding & Brothers. Though essentially built to the same specifications, there were slight variations across the four manufacturers in terms of small details.
Tank helmets were issued as part of a tank's onboard equipment, and were not issued to individual tankers. According to the 1942 War Department Technical Manual TM 9-731A, all M4 and M4A1 Sherman tanks came equipped with five helmets -- sizes 7, 7 1/8, 7 1/4, 7 3/8, and 7 1/2. The M5 Stuart Light Tank came equipped with four tank helmets for its four crew members, although the 1943 Technical Manual TM 9-732 does not specify the exact sizes that were supplied with each light tank.
The following color photos better illustrate the design of the M-1938 Tank Helmet. Shown with this Sears Saddlery size 7 3/8 helmet are Polaroid 1021 goggles with green polarizing lens, a T-30-V throat microphone, and an HS-18 headset with high-impedence R-14 receivers. This setup is consistent with wartime photos of 752nd tankers, and especially typifies a 1944 tanker's helmet configuration. More information on the communication equipment and goggles can be found later on this web page.
Tank Helmet M-1938 (Accessories Typical of 1944)
The M-1938 tank helmet was very light and comfortable to wear. The helmet in the above photos weighs less than 2 pounds when fully equipped with the exact communication gear and goggles shown above. The ten -inch holes in the fiber crown provided adequate ventilation in most operating conditions. However, as discussed in the section of this web page titled "Use of Tape on Tankers' Helmets", the open ventilation holes were not always popular with the tankers.
The M-1938 Tank Helmet was quite distinctive to the Armored Corps and was proudly worn by tank crewmen in all theaters of operation. Motorcycle-mounted MPs in WWII also commonly wore the tank helmet for crash protection. The M-1938 tank helmet continued to be issued through the late 1950's.
Special Ventilation Feature
The patent also allowed for a little-known ventilation feature. The leather retaining strap running transversely across the shell could be affixed to special snaps on the bottom of the ear flaps to keep the flaps in the upright position away from the wearer’s head. This feature was seldom if ever used by any tankers, and for very obvious reasons. The "flying nun" look was just too ridiculous for any self-respecting tanker. More practically speaking, the uplifted flaps would certainly snag on other equipment and interfere with entry and exit, and the lack of side support from the ear flaps made for a much less secure fit when configured this way. In addition, it took time to configure the helmet like this, and since it was not practical to wear the helmet like this inside the tank, a far better ventilation and comfort effect was achieved by simply removing the helmet from the head with one easy movement of the hand!
Clever But Impractical Ventilation FeatureUse of Tape on Tankers' Helmets
While not a very common practice, every now and then a photo appears showing a tanker with masking tape, duct tape, or electrical tape on top of his tanker's helmet. Contrary to previously published theory, the tape was generally not intended to hold communication wires in place. Instead, there were two more common reasons for taping the ventilation holes of a tanker's helmet.
First, tankers' heads were almost continuously exposed to the elements, and the 10 ventilation holes on the top shell of the tanker helmet allowed considerable amounts of rain water to enter the helmet. After dripping down the tanker's head, the water would then run down his neck and dampen his clothing, often for days on end depending upon weather and operational conditions. A little tape over the holes was a quick remedy, at least for the rain that entered through the holes.
Also, WWII tank engines drew a strong and constant flow of cool outside air through any open hatches. Since the top of the tanker's helmet was directly in the path of this air flow, the cool air rushed right through the holes in the helmet and exited along the tanker's neck and ears. Again, a little tape at least stopped the flow of air through the tanker's helmet, and also minimized body heat loss in cold weather.
Tape-Covered Ventilation Holes
The M-1938 Tank Helmet could be worn under the M1 steel helmet for slightly increased ballistic protection, this was seldom done in the field. It was virtually impossible to wear the M1 over an M-1938 Tank Helmet with the M1's liner in place, because the liner's webbing barely fit around the shell of the M-1938 helmet. This meant that the M1 liner had to be removed, which required precious seconds during rapidly changing combat conditions.
In addition, even with the M1 liner removed, the fit was a very tight one. In fact, the fit was so tight that the headset retainer bars had to be jammed under the M1 helmet. Even with this accomplished, the M1 helmet sat very high on the tanker's head and therefore offered little protection around the ears.
Despite the practical difficulties, some tankers did choose to wear their steel pot over their tank helmet for at least a little additional protection against shrapnel. Some tankers claimed that they wore their M1 shell over their M1938 tank helmet during inclement weather to keep the rain and drafts from entering the M-1938 ventilation holes (as discussed previously).
Winter Combat Helmet Used With the M-1938 Tank Helmet
The M-1942 helmet had two "strap and snap" fasteners toward the back of the head for attaching goggles, and a wide chin strap for snugging down the cap and providing a little more protection against the cold and wind. It also featured an extended neck flap, which was intended to keep rain from running down the tanker's neck. Unfortunately, it merely deflected the rain down the back of the tanker's clothing, and often into the tanker's trousers.
Receivers Used in the M-1938 Tankers Helmet
The HS-18 that was originally used with tank helmets was a very simple brown waxed cotton-covered braided cable. Both ends were connected to a high impedence (2000 ohm) R-14 receiver. The length of the cable from receiver to receiver for tank applications was approximately 13 inches, which made for a relatively taut wrap around the M-1938 helmet. (other HS-18 headsets used a slightly shorter 12 inch length). One end of the harness contained a "Y" with one side of the "Y" connected to an R-14 receiver, and the other end connected to a black-shelled PL-54 -inch plug. The "Y" end could be mounted on either the left side or right side of the M-1938 tank helmet to suit the individual crew member's preference. This PL-54 plug on the HS-18 headset was then connected to a JK-26 jack on one end of a 6-foot long CD-307 cable. The other end of this CD-307 cable connected to the tank's BC-606 intercom control box via a -inch PL-55 plug.
The HS-18 headset cable had a built-in strain relief cord, as shown in the photo below. This cord was tied to the strain relief lug on each R-14 receiver with virtually no slack. Because the headset wires had more slack than the tied relief cord, if the cable was pulled, any pressure would be absorbed by the strain relief cord. This prevented the headset wires from being disconnected during operations.
In 1943, the Army Air Corps and the Navy began to switch from the 2000 ohm high impedance R-14 receiver to the 600 ohm low impedance ANB-H-1 receiver. This low impedance headset was referred to as the HS-38 headset (the HS-33 was the same as the HS-38, but it included a headband for non-helmeted applications). The most obvious difference between the original high impedance HS-18 and the later low impedance HS-38 was in the -inch PL-354 plug shell, which was purposely colored red to avoid improper integration with high impedance radio equipment. The ANB-H-1 receiver was similar in size and appearance to the R-14 receiver.
Eventually the armored corps also adapted the low impedance HS-38 headset, but the majority of headsets for most of the war appear to have used the original high impedance HS-18 headset. Through the use of a special Headset Adapter MC-385-C, it was possible to step down the tank radio's high impedance to the low impedance required for the newer low impedance receivers. Thus, as new headsets flowed through the supply chain, it was possible to use them without converting expensive radio hardware. The adapter was installed between the tank's phone jack on the BC-606 intercom control box) and a CD-307-A extension cord (with a PL-55 plug on one end and a JK-26 jack on the other). The CD-307-A extension cord was then connected to the PL-354 plug of the HS-38 headset.
The most common way of routing the receiver headset harness was on the outside of the ear flap, and then under the leather receiver retainer. When routed in this fashion, the receiver harness tended to pull the R-14 receivers outward, which prevented them from sliding inward and moving out of their holding slots.
"Over the Flap" Harness Routing MethodAlternatively, some tankers routed their headset harness underneath the ear flap. HS-18 harnesses intended for aircraft use had a receiver-to-receiver length of 12 inches. Harnesses for tank use were 13 inches in length, as this was the amount of cable required to snugly route the cable along the outside of the M-1938 tank helmet. Much aviation equipment ended up being used by ground forces, and when used with an M-1938 tank helmet, the short 12 inch length required routing under the ear flap as shown below. In addition, a harness that had been shortened due to repairs would also require the "under-the-flap" routing method.
"Under the Flap" Harness Routing Method
Intercom Microphones Used
With Tankers' Helmets
The T-30 throat microphone was the most commonly used tank microphone in WWII. This microphone was strapped around the wearer's neck, with the two 1-inch round pickups contacting the wearer's throat near his Adam's apple. These pickups transmitted sound vibrations as the wearer spoke, and allowed voices to be heard over the background tank and battle noises. The T-30 microphone had a small two-pronged PL-291 plug, which was connected to a JK-48 jack on a SW-141 push-to-talk switch (see below).
The T-45 lip microphone was a noise-canceling microphone designed by Electro-Voice, and allowed the user's voice to dominate over vehicle and battle noise. It was mounted snugly over the wearer's upper lip, and was held in place by soft vinyl straps that wrapped around the wearer's ears. The T-45 lip microphone connected to a SW-141 push-to-talk switch in the same manner as the T-30 throat microphone (see below). When first submitted to the Army Air Corps for consideration, the T-45 was flatly rejected. However, the design was successfully pitched to the Tank Corps, and the demonstration attracted the attention of the Marines Corps, which was interested in a noise-canceling microphone for use in amphibious landing craft. Electro-Voice won the coveted Army/Navy "E" Award for its T-45 contribution to the war effort. The T-45 continued in communications and aviation service for decades, and even saw use in NASA's Mercury, Gemini, and Skylab programs.
The hand-held T-17 microphone was commonly used by tank commanders, as their hands were more free during combat operations than drivers, gunners, or loaders. The T-17 was most commonly manufactured by Shure Brothers Company, and contained a built-in SW-109 push-to-talk switch. The T-17 had a hook on its top to enable the microphone to by hung on the turret wall when not in use. Because the microphone contained a built-in talk switch, the unit plugged directly into the BC-606 intercom control box and did not have to pass through the SW-141 push-to-talk switch that was used with the T-30 throat microphone or T-45 lip microphone. Tank usage of the T-17 favored the black bakelite case over the metal case, because it stayed cooler and more comfortable to hold inside a hot tank (internal tank temperatures could reach 130 degrees in desert operations). The T-17-B became the most widely used microphone in the U.S. Army and Navy.
The SW-141 push-to-talk switch was a small black hand-held switch that was worn around the tanker's neck. It was hung from the tanker's neck by a leather lanyard, which was later replaced by a more durable cotton cord lanyard. The T-30 throat microphone or the T-45 lip microphone was connected to the JK-48 plug that was attached to a short cable coming out of the SW-141 switch. Another cable, approximately 7 feet long, extended from the other side of the SW-141 switch, and connected to the tank's BC-606 intercom control box by a black-shelled PL-55 -inch plug. When the tanker spoke, he pushed a spring-loaded lever on the side of the SW-141 switch.
Three different types of goggles were commonly issued to tankers during WWII for use with the M-1938 Tank Helmet. These were the M-1938 Resistal goggles, the Polaroid 1021 goggles, and the M-1944 goggles.
The earliest of these was known as M-1938 Resistal goggles, which consisted of a pair of clear laminated polarizing lenses, individually framed in metal, and hinged in the center. The lenses were mounted on a leather cushion, which was held snugly against the wearer's face by an elasticized strap. The Resistal goggles tended to restrict vision because of the split frame, and the lenses tended to delaminate. They were phased out of production, and according to a February 1944 T/O&E they were only being issued as a means of depleting existing inventories. Photos of the 752nd tankers show M-1938 goggles still in use in mid-1944.
By early to mid 1944, the majority of tankers were wearing the Polaroid All Purpose Goggle Kit No. 1021. Photos of 752nd tankers specifically show the 1021 model as the standard tanker goggle through the end of the war, even though November 1944 T/O&Es were calling for a different standard (see below). The Polaroid 1021 goggle was developed mainly for use by the Army Air Corps, but it found widespread use in all Army branches. The 1021 all-purpose goggle kit featured a comfortable light-weight foam and rubber frame, held in place by a thin elasticized strap. In addition to improved comfort over the earlier M-1938 goggles, the Polaroid 1021 kit featured a single one-piece lens for better visibility, and four different removable lenses were available for better visibility under a variety of conditions. A non-polarizing clear lens was available for protection against dirt and grime under normal conditions where no glare was present. A light green lens was available for glare protection on normal days, and a dark green polarizing lens was available for glare protection on "exceedingly brilliant" days. Finally, a red non-polarizing "dark adaptor" lens was available for adapting the eyes to night vision.
T/O&Es in November 1944 were calling for the standard use of the M-1944 goggle, and these goggles came into use by ground forces in late 1944/early 1945. However, photos of 752nd tankers do not show this goggle in use until the post-war period. The M-1944 goggle featured a one-piece molded rubber frame, which housed a one-piece lens whose viewing area was considerably larger than that of the Polaroid 1021 model. The frame was held in place by a thick elasticized strap. Like the Polaroid 1021, the M-1944 goggle lenses were also available in a variety of shades for various operating conditions. M-1944 lenses were available in non-polarizing clear, polarizing green, polarizing gray, and non-polarizing red "Dark Adaption" varieties. M-1944 goggles continued as the standard-issue ground forces goggle into the 1970's, and even today's ground forces goggles are only a slight variation of the M-1944.
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Researched by Robert J. Holt