Bofors isn't everything, part 2.

A column of batteries of 40-mm anti-aircraft guns on the march; Zaolziysky district, 1938. Krzysztof Nescior

The appearance of Bofors guns in anti-aircraft artillery divisions called into question the choice of the most appropriate method of transporting not only ammunition, but also the entire complex of equipment necessary for their use.

Trailer with ammunition and equipment

It seems easiest to assign this role to trucks such as the PF621, which would not be able to keep up with the pace and efficiency on the march towed by C2P cannons, especially in difficult terrain, loaded with boxes of ammunition and equipment. Therefore, it was decided to introduce appropriate trailers into the battery, the traction of which - similar to guns - should have been provided by the already developed tracked tractors. After testing on a tractor manufactured by PZInzh. towing the Bofors gun from the end of 1936, it was found that at least two trailers with a carrying capacity of about 1000 kg would be required to transport people, ammunition and equipment within one gun. At the turn of 1936 and 1937, there was an obscure and apparently somewhat chaotic correspondence between the Ordnance Directorate, the Armored Arms Command and the Armored Armaments Technical Research Bureau (BBTechBrPanc) regarding the wording of the requirements to be established for the designed trailers.

A contender?

Finally, the official order for the production of trailer prototypes was handed over, along with the basic requirements, to the United Machine Works, Kotlow and Wagonow L. Zeleniewski and Fitzner-Gamper S.A. from Sanok (the so-called "Zelenevsky"). April 9, 1937 Judging by the surviving documents, this issue was discussed earlier. Probably around the same time, the first Locomotive Works in Poland SA (so-called "Fablok") and the Industrial Society of Mechanical Works Lilpop, Rau and Lowenstein SA (so-called LRL or "Lilpop") were dispatched. at the First Locomotive Plant in Poland. It seems that Zelenevsky's factories reacted the fastest. In the initial assumptions presented by Sanok in February 1937, the ammunition and equipment trailer was supposed to be a 4-wheeled machine with a welded stamped steel frame and a front axle turning 90 ° in each direction. The brake was supposed to act automatically on the front wheels of the trailer in the event of a collision with a tractor. 32 large leaf springs served as the basis for the suspension of pneumatic wheels with dimensions 6x4, and the fifth spring was mounted to dampen the drawbar. The drawer with opening on both sides and fixed ends is made of wood and steel corners. In order to secure the crates placed on the trailer, the floor was supplemented with a series of wooden planks and appropriate clamps (limiting vertical and horizontal movement). The initial version of the trailer doesn't appear to have room for the crew's backpacks.

On July 23, 1937, a contractor from Sanok presented two model trailers in slightly different modifications to the Armored Weapons Supply Directorate (KZBrPants). Both units, however, turned out to be too heavy and somewhat too big for the expectations of KZBrPants - the estimated curb weight exceeded the expected one by 240 kg. As a result, correspondence was preserved about the necessary design changes, in particular about reducing its weight. The body of the KZBrPants model, which was repeatedly modified and adapted to carry a complete set of equipment, was approved only on September 3, 1938. According to initial assumptions, a trailer with a curb weight of up to 1120 kg (according to other sources 1140 kg) was supposed to carry: 1 box with a spare barrel (200 kg) , 1 box with the necessary kit (12,5 kg), 3 boxes with factory-packed ammunition (37,5 kg each, 12 pieces in cardboard tubes), 13 boxes with ammunition (25,5 kg each, 8 pieces .), 8 crew backpacks (14 kg each) and a 32 × 6 spare wheel (82,5 kg) - a total of 851 kg. Despite the approval of mock-ups, December 22, 1937

KZBrPants wrote to the contractor with a letter that a new set of trailers would be sent to the plants, incl. crates not included in inventory so far. The weight of the new cargo is 1050 kg, with an indication that it must be transported in its entirety. It was also postulated that if further work to reduce the weight of the trailer was successful, one more (ammunition?) box and 2 backpacks should be added, but so that the weight of the entire set did not exceed 2000 kg. It is also worth noting that at the end of 1937 there were already 4 exemplary ammunition trailers - two trailers from Zelenevsky and prototypes produced by Lilpop and Fablok. However, in the case of Zelenevsky, the changes did not end, since the surviving list of another 60 modifications is known.

dated August 3, 1938, which apparently does not close the case.

Today it is difficult to determine what the final look of the Sanok trailers was like, and photographs of surviving specimens indicate the parallel use of several different modifications that differ, for example, in the way the spare wheel is attached, the design of the cargo box - the front and rear sides can be lowered, a drawbar is used, the location gunner's backpacks or crate locations. . Suffice it to say that for all type A and B anti-aircraft artillery batteries equipped with Bofors wz. 36 caliber 40mm, at least 300 pieces of equipment and ammunition trailers had to be ordered and delivered, so it was a lucrative order for each of the bidding companies. For example: one of the preliminary calculations of the Sanok factory, dated March 1937, indicated that the offer price of the trailer prototype was about 5000 zł (including: labor 539 zł, production materials 1822 zł, workshop costs 1185 zł and other expenses). . The second surviving calculation refers to February 1938 - so before the introduction of the above corrections - and assumes the production of a series of 25 trailers within 6 months or 50 trailers with a delivery time of 7 months. The unit price of the trailer in this case was to be PLN 4659 1937. In the financial plan for the 38/7000 financial year, concerning the vehicle equipment of the experimental detachment, the price per trailer unit was set at PLN 1938; On the other hand, in other documents containing tabular lists of prices per unit of armament and equipment for 39/3700, the price of a trailer with ammunition and equipment is only PLN XNUMX/XNUMX.