Heinz Gröschl                                       O.U., 25th July 1943

Fpnr. 25 056


Prof. Porsche and Mr. Porsche jun.

Stuttgart-Zuffenhausen

Our vehicles have been operational for three weeks now and on average they have driven 500 km, including the distance driven before. I have collected enough experiences to sketch a view of the performance and failures of our vehicles. In complete agreement with the Abteilung's higher officers, I can say that the weapon was succesfull and it is regrettable that only a small number of it is available. With an average of 15 kills per vehicle one must speak of a success. However, the number of kills may well be higher by now. Unfortunately, most of the vehicles are under repair at present. Moreover, this situation gets worse every day, because no spare parts are left and all parts are wearing out more and more. No new spare parts have arrived yet. Of the original number of 44 vehicles, 17 are missing now. Of these, 7 have been given to the other Abteilung by order of the regiment while the other 10 had to be written off as total loss. The report about the most common damages and troubles is below.

Wheels and rollers
Against expectations, no damage has appeared as a consequence of overloading. The soft ground may have had a vital role in this.The use of rubber buffers (especially for both the hindmost pairs of rollers) and of rubber rings (most for the 5th return roller, located under the exhaust pipe) was very high. The bolts have not got loose, although many of the vehicles have the old tin fuse. More rubber rings have rolled in now and have to be changed. After Neusiedl, no torsion bars have broken anymore. The supports of the wheels have caused no problems. About 20 roller-pairs (swing arm and spring housing) and many rollers have been damaged by enemy action. The most common troubles, most of them caused by mines, were damaged swing arms, cracked spring housings and rollers that are pulled from the bolts and often deformed. The 5th return roller does not hold the grease, as it is very warm. The crack of the suspension pin of the foremost pair of rollers has most likely been caused by mines. Unfortunately, replacement parts are not available in the numbers needed. Parts of damaged vehicles have been used when possible.

Driving gear
Except for a case in Neusiedl, which must have been described by Mr. Zadnik, no incidents have occured yet. You are familiar with enough cases of damaged screws of drive sprocket wheels.

Braking system
Some cases of damage to the brakes in Neusiedl are known to Mr. Zadnik. Untill now no difficulties have emerged. Of two vehicles, one brake drum each has been shot through. The vehicles remained operational for 1 or 2 days, with the damage, but the inner parts were fully destroyed.

Body
Has proven itself to be almost invulnerable for enemy fire. A hit by a 76.2 mm on the side, near the hindmost air intake, only resulted in many cracks. This hit remained without complications. Experience has shown that the welds are vulnerable spots, as, without fire extinguishers an artillery- or bomb hit on or near the welds tends to set the vehicle into fire immediately. The splinters penetrate into the fuel tanks or damage other vital parts, like water pipes. In some instances the fuel in the pipes began to boil due to the very high temperature in the engine room. The attachment of winches, tools and ropes on the outside of the body was wrong. The destruction of these items within a short time could have been expected.

Superstructure
Was penetrated from the side in some cases. The tighting of the hull (the welds) is of very poor quality or even totally absent. Small splinters penetrate through the gun's armour, which resulted in wounded crew-members. The temperature in the crew compartment still is too high. In some instances, the ammunition for the light pistol detonated itself. According to commanders and aimers, the warming of the shells stored on the bottom leads to shots that are too far.

Engines
Engine failure is a much occuring problem. Damages are: valves that bend or are pulled which leads to destroyed pistons, bended or pulled-rods and cracked cylinder-heads. In my opinion, the poor engine power is the main cause of these problems. Cracks and leaking pistons surely are caused by overheating. A water loss of 10 liters is not acceptable, according to experiences. The connections of the exhaust pipe's parts only hold for a short while, which leads to a high risk of fire. The replacement of the connection parts (which are very difficult to reach) is extremely difficult and takes a long time. At present, it is impossible to change broken engines, as reserve engines are not in stock.

Cooling
Leaking coolers and defective ventilators have already caused much work. Most leaks occur in the soldering of the lowest support. I suppose the cause is the short, rigid tube-connection between both cooler's lowest supports. In case of defective ventilators, the drive-flange was welded to the ventilator-shaft. Reserve parts for these are lacking.

Generators, electric engines
In Neusiedl, we had the last trouble with a generator. Again, it was caused by the interruption in the contact still placed in the lower part. After that, no other troubles have occurred. However it must be emphasised that the weather has been dry and that the vehicles rarely cool down entirely. On the other hand, the generators gather much dust, but it does not seem to influence the reliability.

Gear-box
No troubles of any importance occurred. The back-drive of three vehicles has been replaced. These parts gather much dust too.

Electric installation, battery
The electric installation with reversed flow direction has caused huge complications. The total loss of one of the vehicles was caused by the installation. We had vehicles with blown fuses (and empty batteries as a consequence) every day. Mr. Zadnik probably has reported that to you already. We have decided to convert the electric installation to the former flow direction and have finished this work on 9 vehicles. With these converted vehicles we have had no more problems. Unfortunately Mr. Scharpf of the Bosch company, who assisted us in converting the installations, has died in action. The installation of the batteries is bad. The first day of our attack has cost us more than 30 batteries. In all cases the housings have been flattened or totally destroyed. Every vehicle that has droven onto a mine has lost one or both of the batteries. Sometimes enemy fire has the same effect. Both the batteries of the radio installation have had to meet strong demands and thus they often have to be reloaded outside of the vehicles.

Telekinz, speedometer
Troubles also occur on telekinz and these can only be repaired with great effort, as we have not received one single spare part. The speedometer of many vehicles has gone down. These vehicles are used without speedometer. Instruments like that, which are very difficult to reach for repairs, must function with great reliability, as in operational circumstances there is no time to replace those parts.

Main gun
The gun works very well, but needs many repairs. The rifling in the barrel breaks for unknown reasons and the installation that throws the empty case out does not work. The cases often have to be removed with hammer and chisel. Cross-country drives with a gun that is not fastened results in a moving gun (both horizontally and vertically), with a deflection of up to 20 cm at the muzzle. The gun's aiming devices often jam due to the high temperature rise within inside the vehicle. After a short period of operations the gun has to be calibrated again. The forward barrel support has been shot off in some cases. An accurate report has been given to the commander of Abteilung 653 by Stabsfeldwebel Br. to be forwarded.

If you're interested in more info or photos, please read the following mentioned books.

Literature:
- Schwere Jagdpanzer, Spielberger, Doyle, Jentz, 1996, Motorbuch