German 700-strong Maybach HL 230. Source: vpk.name
Soviet history of the Hitler motor
History about the appearance of Maybach HL 230 at ZIL should start from 1943-1944, when in Kubinka a full analysis of the design of a gasoline engine tank Pz V Panther. One of the first sources from which Soviet engineers and the military learned about the intricacies of engine performance was the Bulletin of the Tank Industry. In the article “German Tank Engines,” senior lieutenant technician Chistozvonov examines the evolution of enemy tank power plants. HL230 acts as a more powerful modification of the "brindle" HL210. In fact, the “two hundred and tenth” engine was installed only on the first 250 copies of heavy tanks. It was decided to replace the twelve-cylinder carburetor power unit due to the relatively small power of 650 liters. with. and low reliability at about 3000 rpm. But it was precisely in this region of revolutions that the torque was close to maximum. But the Tiger could not fit a larger motor, so Maybach-Motorenbau GmbH decided to increase the working volume by 10% and replace the aluminum cylinder block with cast iron for greater reliability. It turned out to remove 700 liters from the new engine. with. that with a working volume of 23,88 liters was an outstanding indicator for its time. These Karl Maybach engines under the HL 230 index became the main ones for the line of modifications of Hitler's heavy and medium tanks. Lieutenant Chistozvonov mentions in Vestnik that the Germans increased the intake valve diameter to 60% of the cylinder diameter, installed 4 Solex TFF-2 carburetors (one unit for every three cylinders), increased the compression ratio to 7,5 and dispersed the piston to medium speeds of 16 m / s. The inlet valves were sodium-cooled, and this, according to the author, allowed the engine to run on 74th gasoline, despite the increased compression ratio. Such technical solutions became the basis for boosting the engine, which made, in particular, reinforce the crankcase due to increased loads.
Pz V Panther from the collection in Kubinka. Source: militaryarms.ru
Among other features of the engine, Soviet military engineers paid special attention to devices for underwater driving of the tank. The Germans carried radiators and fans of the cooling system into separate compartments filled with water, while the HL 230 itself was sealed on both the Tiger and Panther. Fans, by the way, at the entrance to the water were disconnected from the drive by cardan shafts using friction clutches. For cold climate conditions, a thermosiphon heater with a portable blowtorch was provided.
Despite the mass of interesting engineering solutions, the author of the material in the Bulletin of the Tank Industry concludes that the design of the HL 230 is not brought to the required level of readiness and has serious shortcomings. So, the engine inherited from the previous model got a tendency to penetrate too narrow jumpers of the cylinder head gasket between adjacent combustion chambers. Incidentally, this was aggravated on the HL 230 due to an increase in the working volume of the cylinders with constant block sizes. Maybach-Motorenbau engineers even removed the common gasket from the gas joint, replacing it with separate aluminum rings, which also burned out.
Maybach HL 230. Source: en.wikipedia.org
In pursuit of power, we had to reduce the distance between the cylinders and even thin the cylinder liner, which very negatively affected the performance of the Pz V Panther from the museum’s collection in Kubinka. But more on that later. Another consequence of the high degree of acceleration of the motors were frequent valve breaks and burnout of the pistons. The general conclusion of the article by Lieutenant Chistozvonov on the analysis of the development of tank engine building of the Third Reich was the thesis: "The older the design, the higher the reliability." High liter engine power as a requirement of "thickened" Hitler armored vehicles has become an important factor in the loss of reliability and resource.
For many decades, Soviet and, later, Russian engineers didn’t even remember the “fiery hearts” of the fascist German tank industry. Fortunately, domestic powerplant designs were based on other ideas. But when the military in 2012 needed to revive the museum Pz V Panther, there was an incident: they could not manage on their own in Kubinka.
Wizards from the experimental workshop
Visitors to the museum in Kubinka will probably remember the spotted Panther with a tactical number on the II II 11 tower, which is one of the few German exhibition vehicles capable of independent movement. Museum workers revived him in 2012 and even managed to ride around the complex, but soon noticed that the oil in the engine turned into a water emulsion. There were serious problems that precluded the further operation of the tank. But it was not possible to solve it by the Ministry of Defense - the innovations and reforms of the then Minister Serdyukov did not leave specialists in the entire Moscow Military District capable of such repairs. The engine, obviously, was in a single copy with a minimum set of spare parts.
Maybach HL 230: moments of operation and training of personnel. Source: www.alanhamby.com
As Vladimir Mazepa (in 1992-1994 and 1998-1999 - the chief designer of AMO-ZIL) mentions in his book "Legends and Tuffel Groves", the director of the museum Andrei Sorokova and the representative of the restoration department Alexander Anfinogenov turned to the Likhachev Plant for help. On the part of the ZIL experimental workshop, to which this work was entrusted, engineers Nikolai Polyakov, Vladimir Kharinov and Andrey Zharov participated. The motor from the tank was dismantled, loaded into the “Bychok” and taken to Moscow in the bureau for the study and refinement of trucks of the experimental workshop. The Maybach HL 230 “Panther” motor was put on a stand and, for lack of detailed instructions, they searched for the cause of water entering the oil sump by brainstorming. Even the process of disassembling the motor had to be outlined in detail, otherwise it would be difficult to bring it to its original state. Initially, it was determined that the leak was somewhere in the region of the third cylinder, but the reason was determined a little later: it was a long, almost the entire cylinder, longitudinal wall crack. At the same time, the engineers determined that the engine of the German tank is almost untouched, the wear is minimal, but in the 10th, 11th and 12th cylinders there are traces of foreign objects. Intake valves were bent in the same cylinders and, accordingly, piston bottoms were riveted. How can one not recall the highest reliability of engines, which was mentioned in an article back in 1944! The valves were aligned on the equipment of the experimental workshop, but there were problems with the cracked cylinder liner. For several weeks there was no news from Kubinka, although museum workers promised to find and send something suitable from the repair kit to Moscow. We decided to do it on our own. Metallurgical researchers have determined that the sleeve is made of gray cast iron, and accurate measurements showed similarities with a similar spare part from the domestic YaMZ-236 motor. The Maybach piston was ideally suited to the sleeve of the Yaroslavl motor! It only remained to grind the workpiece from the outside: we remember that the Germans on the HL 230 model increased the working volume of the tank engine by simply boring the cylinders and thinning the walls to 3,5 mm. Such "elegance" of the design, obviously, became the cause of the breakdown of the German tank in the distant forties - a completely new engine simply overheated.
Faulty German tank engine in the ZIL experimental workshop. year 2012. Source: "Legends and were Tuffel Grove", author V. G. Mazepa
Further, in the work of Moscow specialists, the question arose of laying the cylinder head. She, contrary to the data of Lieutenant Chistozvonov, was still present, and not even alone. The water jacket was sealed with more than a meter long gasket made of a metallized gasket sheet, and the fire belt was sealed with an annealed copper ring. A possible reason for this discrepancy in data was different modifications of engines that fell into the hands of domestic engineers in 1944 and in 2012. Copper for the fire zone was found and the rings were made, but the Klingerite gasket was made of material that was selected by the technologists of the experimental workshop.
When the Maybach HL 230 was assembled, put on the stand and launched, taking into account all the improvements, the oil-water emulsion in the crankcase was no longer observed, but the motor itself was very unstable. After several days of the next brainstorming, the shotdown phases of gas distribution in one of the semiblocks were determined. Normalized motor operation according to the German instructions in 1944. By the way, they did not determine who had knocked down the phases of the German engine: perhaps this was done during the research of the tank in Kubinka during the war. Perhaps Lieutenant Chistozvonov took part in this ...
The motor for the Pz V Panther from the exposition in Kubinka revived. The tank is still operational, participates in military reconstruction and festivals. But the engineering potential of ZIL, which was gloriously manifested during such "resuscitation", could not be maintained.