Filling and Adjusting the PT34
(Picture by courtesy of Carles
Filling the Patronentrommel 34
To be able to fill the PT34 the user will need some kind of tool. The answer was a special machine named Trommelfûller 34. It consisted of a gearbox, a vice, a hand crank and a funnel. All parts could be stowed inside a standard Patronkasten 34.
Trommelschlüsseln und Sperrohr zu den Trommelschlüsseln
funnel with 75 rounds. As the magazine will not function properly if it
is overfilled, it is important that the correct number of cartridges is
put into the funnel. By turning the crank-handle the drum will be
filled with the cartridges placed in the funnel.
Up untill now, no surviving example has been known to exist. Then this set of pictures surfaced in France!
This clearly is a surviving example of the Trommelfüller 34.
And then another Trommelfüller 34 was "unearthened" in Russia!
picture by courtesy of David in Moscow! This one has clearly been dug
up, but is very interesting as it is displayed in parts!
Adjusting the Patronentrommel
The PT34 was a finely tuned machinery. Too weak springs would lead to feed-failure, and too hard springs would lead to the gun jamming, as the bolt spring would be unable to overcome the pressure of the cartridges against the magazine lips. To top this, both springs would need to work perfectly in synchronization to ensure that the feeding occurred from both drums. The drum spring-adjustment was not carried out by the user. The manual clearly states that any trouble with the feeding should first be remedied with the Trommelschlüsseln. "Wiederholen sich Störungen bei einzelnen Patronentrommeln, so ist die Federspannung durch das Waffentechnische Personal zu verändern". If feeding problems persist with specific PT34's, the springs should be adjusted by Ordnance personnel! It is easy enough to figure out how it was done, but not the correct procedure applied. None of the handbooks I have access to says anything about the actual process.
To get access to the springs, the two disks covering the holes on the front plate must be removed. The two tiny screws are permanently affixed to the disks, so they will not be lost! With the disks removed the construction of the simplified spring is easy to see!
The coiled spring has a final that goes across the last coil. This straight piece of the spring is arrested in teeth that follow the inner wall of the front plate all around the hole, so that two opposing teeth will always hold the coil in the right place and tension. When the covering disk is installed it will lock the coil final in the choosen position.
The coil can be adjusted with a pair of pliers, but the Germans had of course designed a special tool for the job! The name of it is not known. My example came with a “Kleines Waffenmeister Kiste” and was manufactured in 1943, the same year as the PT34 definitively had gone out of fashion! This one was made by “dpq”, Bruno Mädler, Werkzeugfabrik, Berlin.
The tool is very simple to use. First make sure the locking lever is not covering the axis between the notches in the tool, insert it into the hole and make sure the notches and the coil final lines up. Then turn the locking lever so that the coil final is held firmly arrested in the notches of the tool. The coil can now be wound and unwound with the tool while pressing the spring in so that the final disengages from the teeth. Pulling the tool out will bring the coil final into locking position between the teeth again!
When the adjustment has been made, the locking arm is turned again and the tool can be withdrawn.
(Pictured above is a PT34 that was sold on the WAF in 2008)
The front of the magazine housing has impressed a “0”, presumably for zero tension, an arrow indicating increased pressure (these arrows point in opposite directions of course) and a “V”, presumably for Verschärfung (tightening). Also note that the springs have been painted red or white (picture further up), and that the colour of the markings on the magazine housing corresponds with the springs. Most probably to ensure that the correct spring was installed on the correct side!
My best guess in regards to adjustment is that the spring was “zeroed”, and then it was ensured that the cartridges were held firmly in place. Too weak springs would allow cartridge # 2 to jam in the feeding. Springs would have to be tightened until feeding ran smoothly. Over tightening the springs would lead to feed failure, as the pressure of the bolt spring would be unable to overcome the magazine spring pressure on the cartridges. This procedure would be done on the gun with “Werkzeugpatronen” (tool-cartridges) or by using a broken firing pin, and repeatedly cycling the gun by hand with the magazine installed.
Final approval would acquire the gun to be test-fired with a full magazine.