HOW TO IDENTIFY YOUR ¼ TON TRAILERBy Chuck Lutz CA. USA
Updated 8th November 2014
Not long after the jeep was introduced to the US Army and other forces, it was often photographed towing the WWII 37mm Anti-Tank gun. Even when the crisis over the eventual weight of the jeep called for scaling back the design of the frame and components to save weight, it seems the addition of the Pintle Hitch survived the cut. While the jeep was put into production as early as late 1941 and really got into production in early 1942, the design and production of the ¼ Ton trailer did not bring any of them into service until late summer of that year.
There is the story of how Bantam was awarded a contract to build the trailer along with Willys since they had been beaten out in the original design competition for the jeep. I have no idea if this is an urban legend or if it is the truth, however the first contract for 10,000 trailers was awarded to Willys Overland and the next contract was handed to the American Bantam Car Company for 5,000 units. Both began assembly of the trailers using the Tub/Frame assembly constructed by American Central Manufacturing Company (who made the composite tubs for both Ford and Willys jeeps later on).
The first production being accepted by the government from Willys and from Bantam was in August of 1942 and from Bantam possibly in September of that year. Testing and approval most likely proceeded the acceptance dates by some time. Records provided from the Australian War Museum show that very large numbers of the early Willys and Bantam contracts were sent to Australia (or to an Australian government acceptance facility in the South Pacific?). The Australian government accepted them, removed the data plates and painted them with their version of the “USA” number that identifies American vehicles. Some Australian trailers still have their original data plate, but I surmise that these came into their possession outside of the original “Lend Lease” channels. Those trailers left by American forces or even British forces in the South Pacific that may not have had the data plates removed are found in Australia even today.
Production at both plants proceeded Monday through Saturday at a rate of sometimes 500-600 per week to higher numbers during the late ’42 – ’43 period. Contracts were continued with both companies up to March of 1944 when the last ¼ ton trailer from Willys rolled off the line. Perhaps the end of the war seemed in sight and even those at Willys Overland were looking forward to the CJ projects and were possibly quite happy to have that part of their production facility returned to other duties when the production of the ¼ Ton trailer was halted. I have no idea if Willys had a hand in the end of the production at their facility or not. The Bantam Car Company produced the trailer up to July of 1945.
The slowing of the Allied march across Italy, France, Belgium and the Netherlands into Germany in late 1944 must have caused the American procurements officials to rethink the cancellation of the Willys production. They granted contracts to several companies in the United States to begin production of additional ¼ Ton trailers, which began appearing in April of 1945 and were produced for at least the next four months in some cases. The following companies are generally accepted to have been granted contracts and USA numbers issued to them for manufacturing, however the lack of some examples may indicate that some of those contracts were actually canceled before production ever began. It is interesting to note that the design of those trailers followed the Bantam style of shock mountings using nuts to secure the shocks instead of cotter pins.
Fruehauf Trailer Co. 975
Springfield Auto Works 850
Pacific Fabricating Co. 1891
Utility Trailer Manufacturing Co. 492
Transportation Equipment Company 221
Checker Cab Co.
Adam Black 527
Converto 2100 to 6100
Note: These are the Becker-Denzler figures and some additional ones provided by Dave Aro, a Converto aficionado.
These have been reported to have been issued USA numbers which would indicate the contract as having been granted to that company.
The exception to the design of the trailers
following the Bantam style would be the Converto Company. They produced at
least three types of trailers, including one that is nothing at all like the
standard ¼ Ton and has no fenders and a “dump” feature on it. This is often
found with the Engineers or Seabees markings. Another is an exact copy of the
Bantam known as the T-6 and another one that is like the Bantam but with a
tailgate known as the T-7.
The following characteristics will help you identify your ¼ Ton WWII trailer.
1) Produced by American Central Manufacturing Company for Willys and Bantam and probably the other companies who produced this design.
2) ACM identified each unit with a number stamped on the bottom of the gusset plate on the frame. It can be located by removing the four bolts that attach the left front spring hanger to the frame/gusset and wire brushing the gusset plate.
3) Early ACM production included the Shock Mounts on the frame with cotter-pin style attachment for Willys and threaded-for-nuts for the Bantam factory. The addition of a “W” or a “B” to the ACM number enabled the ACM workers to easily identify which tub/frame assemblies were to be shipped to which buyer.
4) Later ACM production did not include the riveted-on Upper Shock Mount so that uniquely designed part could be attached by the purchaser and ACM could ship any assembly to either purchaser and not ship any with the “wrong” type of shock mount on it to either buyer. This eliminated the need for ACM to mark the frames with the “W” or the “B” from that time forward.
5) An interesting design change to the frame is the VERY early style, which did not have the crossmember at the extreme rear of the frame beneath the tub. Later production had one of the mid-crossmembers welded into the end of the frame. I have no indication as to the change date, however I believe it to have been early in the first contract for Willys only. The additional strength to the unit is obvious and the ability to add a pintle hitch to this rear crossmember for tandem towing was therefore possible. The Willys-produced TM 10-1230 of July 1942 pictures the rear of the trailer without the rear crossmember, however though original copies of the Bantam-produced TM 10-1281 utilize the same photo, I have never seen an example of an early trailer WITHOUT the rear crossmember.
6) You may find numbers/letters stamped into the front edge near the handbrake or at the left corner. These can be anything from the Serial Number, the ACM Number, a rebuild facility inventory number, a foreign government inventory number or a previous owners’ Social Security number or Service number!
7) Taillight mounting brackets are bolted to the tub with two bolts per bracket. Early production tub/frame assemblies had the brackets welded to the tub. This was done at the ACM factory. If you have these brackets welded to the tub and no holes for bolts can be detected, this may offer a clue as to the trailer being a very early one!
8) The tub will have only ONE drain assembly located near the left rear of the tub. Those with TWO drains, one forward and one rear are found on M-100 trailers.
9) Tubs found with a metal handle welded vertically to each of the four corners are M-100 trailers.
10) WWII trailers will have FOUR tie-down hooks on each side, one on the rear and two on the front. Post war Bantam Civilian trailers will have THREE on each side.
11) WWII trailers do not have “stake pockets” in the tub from the factory. Post-war Bantams do have this feature.
1) If it is missing, the four holes are found on the font panel near the top and the left side of the trailer. They are slightly less than 3 ¼” from left to right and a bit more than 2 7/8” from top hole to bottom hole.
2) If they are that wide, but only half the height or less….this is a post war Bantam data plate dimension or perhaps a foreign-made data plate diagram or a US Base Ordnance Rebuild plate.
3) Often the holes are simply welded shut by a previous owner; sand lightly here to reveal this modification and to check the dimensions.
1) Early Willys have a cast center section. It will have Willys “WO” part number cast into it. This axel is made from jeep rear axle housings and a center section to join them. It is found on EARLY Willys trailers. I have not yet determined a date in which this design was changed, but imagine this to have happened by the end of 1942 production.
2) Is seam-welded in the center? This is the second Willys design, eliminating the center cast section and freeing up additional foundry output for more critical items.
3) Is a smooth tube design. This is the Bantam axle design as they did not have existing jeep rear ends to modify, so Bantam simply created their own solid tube design.
Landing Leg: (Support Leg)
1) The same design was used for all trailers with the exception of the Converto dump trailers.
2) They are bolted to the support bracket using two Castle nuts on the front of the Support Leg.
1) Can be identified by the THREE holes for the UP, Down and Halfway setting the Support Leg can be set for.
2) The M-100 Support Bracket is similar but only has TWO holes for Up and Down settings.
1) Bolts the two drawbars extending from the tub/frame assembly together along with the Safety Chains and provides the pivot point for the Support Bracket & Landing Leg to move on.
2) Has a grease zerk and ¼-20 threaded hole on the top for a loom clip to hold the Coupling Socket Cable.
1) Bolted under the trailer and again at the Drawbar Bracket, these are interchangeable from left to right down to the holes for the loom clips for the Cable. (if yours are damaged you may reverse sides and thereby put the damaged top rail on the bottom if this is an issue)
2) Often are found with numbers/letter stamped on them. Placed there by US forces or rebuild facilities or foreign governments who often removed the existing data plates. May be the Serial Number, the USA Number, a rebuild facility inventory number, foreign government inventory number or a previous owners’ Social Security number or his Service number!
1) The WWII trailers had a slightly flattened hook on them. Some with a more pronounced round shape are from the Ben-Hur trailers and were put on in the field to accommodate larger vehicles like the WC series that required longer chain length.
2) Each chain has TWO longer links at each end and SEVEN shorter links in the middle.
3) M-100 chains had additional links in them. Some WWII trailer chains had additional links inserted to assist in safely chaining the trailers to vehicles larger than the jeep such as the WC series vehicles.
Taillights & Reflectors:
1) Generally speaking, Willys used Corcoran-Brown buckets and doors and CB reflector bezels and Grotelite 100 inserts.
2) Generally speaking, Bantam used Arrow-Safety buckets and doors and CB reflectors and Grotelite 100 inserts.
3) Other buckets and doors and reflector bezels have been found on LATE production trailers, but it is most likely they were installed at rebuild facilities or in the field. Certainly the Willys trailers would have used the manufacturers listed above as their production ceased in February of 1944…
1) Fenders on all but the exotic Converto units were the same.
2) An indication as to the maker of the trailer and if it had been through a rebuild program can often be found by inspecting the fender bolts for “EC” or “AA” markings usually found on Willys produced units or the “BC” found on those from Bantam Car Company. Markings on the other late production trailers are not known, possibly they are blank.
3) WWII trailers had ROUND fenders. Post war US trailers had hexagonal shaped fenders. Allied produced WWII trailers had hexagonal fenders. (Australian & British)
1) The lunette ring on the WWII trailer has an opening of approximately 3”. The shaft of the Lunette is thinner than the diameter of the Ring on the shaft.
2) The post-war M-100 Lunette has a thicker shaft and is the same diameter as the Ring on it.
3) There are Swiss post-war trailers (US made) with a Lunette that has a significantly SMALLER opening in the ring. These are NOT original to the trailer and are part of the Swiss rebuild program. They may be used on pintle hitches on US-made vehicles as they will fit.
4) Some Lunettes are found with a raised/cast “WO A-6370” on them. Obviously for Willys. I have observed no markings on Bantam-produced Lunettes.
5) Lunette is held on to the Drawbar Bracket with TWO round washers and ONE round washer with a tooth that rides in the groove on the threaded portion of the Lunette. One large Castle nut holds the washers and the Spring on the shaft.
1) WWII trailers used a mount that was riveted together necessitating the holes in one side for bucking the rivets. Post-war trailers did not use the rivets to assemble them so these mounts do not have the three holes in them.
2) Note that many WWII trailers were used in the production of Early Post-War Bantam T3-C (civilian) trailers until supplies were used up.
1) Upper shock mounts were riveted to the frame on early trailers as explained above, cotter-pins were used on Willys and nuts were threaded onto the mounting pins for Bantam and the other manufacturers. Late production trailers had these mounts added by the company that assembled the ACM tub/frames.
2) Lower shock mounts followed the design of the upper ones; Willys using the lower mount from the jeep and Bantam producing one that matched the threaded-nut type they used.
American Central Manufacturing:
1) American Central produced the tub/frame assemblies for almost all ¼ ton WWII trailers.
2) The inventory number was stamped on the gusset plate on the frame located beneath where the left front spring hanger was bolted.
3) Look for numbers stamped in using approximately 7/16” tall numbers. Reveal them with a wire brush. The highest numbers found are in the 153,000 range. Remember that EARLY units came with a “B” or “W” also.
4) Separate series were not kept for each manufacturer. One group of numbers could go to Bantam (the “B” designation, the next group to Willys (the “W” marked ones) and the next sent to Bantam. They were supplied on an as-needed basis. The inventory capacity, the production capacity and available shipping would effect who got what series of ACM numbered assemblies.
5) It is possible to determine if Bantam or Willys produced a given assembly in most cases even with a missing data plate or a missing USA number. From that, the range in which known examples have come to light will enable us to estimate a Serial number, DOD and USA number for a trailer lacking any of those.
6) Until the elimination of the Upper Shock Mount which determined which factory got which style, ACM had to keep twice the inventory on hand or face being unprepared for an order from one or the other buyer if they did not have any of that type in their inventory. This would possibly mean a wait for shipping an order if that style was not in stock. This is why the elimination of the shock mount being installed at ACM streamlined the process.
FOREIGN PRODUCED TRAILERS
Several countries have produced copies of the WWII ¼ Ton trailer. France, Belgium, the Netherlands and Japan and possibly others I am not aware of produced them over the years. After WWII with the Japanese economy in a shambles, American forces stationed in the Pacific routinely sent vehicles to be rebuilt at base rebuild facilities. Japanese industry formerly used for war production was used to supply parts and eventually with the coming of the Korean War, Mitsubishi (they made the Zero fighter) was even licensed by Willys to produce ten-leaf springs. The quality and detail on those copies is excellent with even the welding patterns faithfully reproduced by the Japanese. It is thought that the Mitsubishi factory in Nagoya provided parts, if not actually building the entire copied assembly for the Japanese Defense Force as the Japanese military as called after the war. They produced parts for the rebuild program, possibly even providing parts to the US rebuild facilities, and eventually even built 100% new units for the JDF. It is not know if they supplied these “new” units to the US forces for the Korean War, but it seems likely some came into the possession of the US or NATO forces during that crisis.
These trailers can be identified by a marking on left side of the trailer frame just back from the front and ahead of the fender. A five or possibly six digit number flanked front and rear by a symbol that can best be described as close to the five-leafed “Cherry Blossom” design. Ten-leafed springs with a slightly flattened “U” shape that nest together and are marked “WILLYS” and have the Mitsubishi “Three Diamonds” logo on them have been found with dates stamped on them from March and October of 1954.
If you come across a trailer with NO data plate that seems to confirm to many of the details outlined above, take a quick look at the following and send me the results of your search. I will try to estimate the information you are lacking in terms of Serial Number, DOD, USA Number and manufacturer.
Chuck Lutz can be reached by email here