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Kältefettmarkierungen (Cold Resistant Grease Markings) The beginning of World War II in September 1939, and the soon realized shortage of petroleum in Germany, initiated intense efforts to develop synthetic petroleum lubricants. Just one month after the Fall of France in June 1940, the German High Command was already planning the invasion of the Soviet Union in July 1940 (under the codename Operation Otto), which Adolf Hitler authorized December 18, 1940. The anticipated invasion of the Soviet Union prompted first attempts to improve the cold resistant grease used in German optical equipment. The kältebeständiges Fett (cold resistant grease) — “Invarol” — marked in weißer Schrift (white letters) “K.F.” or “KF”, was introduced May 27, 1940 and began to appear on Dienstgläser produced in Germany and occupied countries later in 1940 and early in 1941.  Soldiers of the 1st SS Panzer Division (Leibstandarte SS Adolf Hitler) near Kharkov, February 1943 Germany’s unprovoked attack on the Soviet Union (Operation Barbarossa) Sunday, June 22, 1941 initiated bitter war on the Ostfront (Eastern Front) between Germany and the Soviet Union, and continued to press emergency research efforts to develop and manufacture effective synthetic lubricants for the German armed forces. Germany’s attack on the Soviet Union arose from Nazi ideological desire to conquer western Russia, repopulate it with Germans, seize the oil of the Caucasus and the agricultural resources of Ukraine, and use the Slavic people as slave labor for the Axis war effort. Unbelievably brutal war on the Eastern Front turned out to be the most crushing military disaster in human history. Four years of vicious warfare, fought with unprecedented violence and destruction, resulted in the deaths of more people on the Eastern Front than in all other fighting across the earth during World War II. Germany’s ultimate defeat in World War II changed the history of the world, creating a political vacuum in the eastern half of Europe that was filled by the Soviet Union’s seizure of Bulgaria, Romania, Hungary, Poland, Czechoslovakia, and the eastern half of Germany, that divided Europe into Eastern and Western blocs for nearly 50 years. The absolute defeat of the German 6th Army and its Hungarian and Romanian allies in the Battle of Stalingrad (August 1942 – February 1943) demonstrated the inadequate performance of German petroleum products in extremely cold weather when lubricants used in tanks, aircraft, and other military vehicles gelled, so that the engines could not be started.  German soldiers in Russia pulling a car from the mud, November 1941 Heated shelter was hard to find, with only a few stoves available. Horses died by the thousands. Tanks and trucks floundered in the mud, skidded on ice, often would not start, and frequently suffered engine damage for lack of antifreeze. Horses could not keep their feet for lack of horseshoes, disrupting the crucial movement of artillery and supplies. Weapons froze and broke for lack of cold resistant lubricants. Men, animals, and equipment suffered to the limit of endurance in the brutal nightmare of savage warfare in the bitter Russian winter. The extreme stress of intense warfare conducted in bitterly cold winter weather on the Ostfront also revealed the inadequacy of even the grease used in German military and naval optical equipment. Under great pressure, the German chemical industry leaned into the task of developing a truly effective cold resistant grease for use in optical equipment of the German armed forces. Improvements in the development of cold resistant lubricants continued to be introduced throughout the war. Special synthetic cold resistant greases were developed to make it possible for German optical equipment to function properly in the bitterly cold extremes of Russian winters. Estimating Dates Using Kältefettmarkierungen (Cold Resistant Grease Markings)  The extreme stress of intense, brutal warfare conducted in bitterly cold winter weather on the Ostfront revealed the inadequacy of grease used in German military and naval optical equipment. Production records of German optical equipment manufacturers (except for some serial number series of the Carl Zeiss firm of Jena, Thuringia) were destroyed during World War II, so there is no way to accurately match serial numbers with date of manufacture for most German optical equipment produced during the war. One way to estimate the approximate year of manufacture and likely service history of German military and naval optical equipment is by their cold resistant grease markings. The German chemical industry experimented with cold resistant greases in response to German combat experience in extraordinarily bitter cold operating conditions in Russia. Four distinct cold resistant greases (KF, O, +, and Δ) were developed from early to late in the war, each identified by a unique mark that was applied to each individual piece of optical equipment at the time of manufacture or when the equipment was returned to a support facility for maintenance, repair, or regreasing. Kältefettmarkierungen (Cold Resistant Grease Markings) “K.F.” or “KF” (1940 – 1941) “K.F.” or “KF” — kältebeständiges Fett (cold resistant grease) — “Invarol” (also known as Busch “Calypsol W 11 fest” (“Calypsol W 11 hard”), “C-fette“, (“C-grease”) — marked in weißer Schrift (white letters) “K.F.” or “KF” on Dienstgläser (Service glasses) manufactured (or returned to a support facility for maintenance, repair, or regreasing) during 1940 and 1941, introduced May 27, 1940. According to Allgemeine Heeresmitteilungen (General Army Releases), the cold resistant grease “Invarol” was introduced May 27, 1940, and was certified to be fully operational for use on equipment to -20° Celsius (-4° Fahrenheit). In the United States War Department Technical Manual TM 30-506 : GERMAN-ENGLISH MILITARY DICTIONARY, dated 20 MAY 1944, “Invarol” was described simply as a kältebeständig (cold resistant) grease. “O” (1942) “O” — kältebeständiges Fett (cold resistant grease) — “Vakuumfett 1416” (“Vaccuum Grease 1416”), also known simply as “Vacuum” — marked with a hellblaue Kreis (light blue circle) “O” on Dienstgläser (Service glasses) manufactured (or returned to a support facility for maintenance, repair, or regreasing) during 1942. According to Allgemeine Heeresmitteilungen (General Army Releases), the cold resistant grease “Vakuumfett 1416” was introduced no later than January 26, 1942, and was certified to be fully operational for use on equipment to -40° Celsius (-40° Fahrenheit). The earliest document referring to “Vakuumfett 1416” — “O” — was the German Taschenbuch für den Winterkrieg (Manual for Winter Warfare), first version dated August 5, 1942. “+” 1942 – 1944 (mainly in 1943) “+” — kältebeständiges Fett (cold resistant grease) — “Instrumentenfett 1442” (“Instrument Grease 1442”) — marked with a hellblaues Kreuz (light blue cross) “+” on Dienstgläser (Service glasses) manufactured (or returned to a support facility for maintenance, repair, or regreasing) during 1942 and 1943. According to Allgemeine Heeresmitteilungen (General Army Releases), the cold resistant grease “Instrumentenfett 1442” was introduced no later than August 6, 1942, and was certified to be fully operational for use on equipment to -40° Celsius (-40° Fahrenheit). The earliest document referring to “Instrumentenfett 1442” — “+” — was the German Taschenbuch für den Winterkrieg (Manual for Winter Warfare), revised version dated November 1, 1942. Evidently, soon after it was introduced, “Vakuumfett 1416” turned out to be unsatisfactory in actual field use. In the revised version of the Taschenbuch für den Winterkrieg (Manual for Winter Warfare), dated November 1, 1942, the “O” marking was not mentioned, and the “+” marking was introduced without explanation, with the statement that optical equipment marked with a “+” was perfectly serviceable to -40 degrees Celsius, and “in Zukunft wird das gesamte Beobachtungs und Vermessungsgerät des Heeres nur mit Instrumentenfett 1442 gefettet” (in the future, all observation and surveying instruments of the Army will be only lubricated with Instrument grease 1442″. “Δ” 1943 – 1945 (mainly in 1944) “Δ” — kältebeständiges Fett (cold resistant grease) — “Instrumentenfett 6009” (“Instrument Grease 6009”) — marked with a hellblaue Dreieck (light blue triangle “Δ”) on Dienstgläser (Service glasses) manufactured (or returned to a support facility for maintenance, repair, or regreasing) from 1943 to 1945. Although no document exists referring to “Instrumentenfett 6009” — “Δ” — it is believed that this final cold resistant grease was introduced in late 1943 or early 1944, and was certified to be fully operational for use on equipment between -40° and -50° Celsius (-40° and -58° Fahrenheit).  Here is an example of a Dienstglas bearing all four cold resistant grease markings KF, O, +, and Δ. The manufacturer code “beh” shows that this Dienstglas was manufactured in Germany by the Ernst Leitz firm of Wetzlar, Hesse. The cold resistant grease markings tell the story that this particular Dienstglas was manufactured (or returned to a support facility for maintenance, repair, or regreasing) sometime in 1940 – 1941 (KF), then returned to a support facility and regreased in 1942 (O), again sometime in 1942 – 1944 (+), and finally sometime in 1943 – 1945 (Δ). The chronology of the markings is known, although the timing of each event is inexact. The exact dates when the four successive cold resistant greases (KF, O, +, and Δ) were actually applied to Dienstgläser at individual factories (or support facilities) in Germany and occupied countries in Europe was approximate and inexact, and varied according to when supplies of existing greases were used up at each individual factory, and when shipments of new greases arrived at each individual factory for continued use in production. However, it is clear that the four different cold resistant greases were introduced into service and used in a known chronological order.
Cold resistant grease markings were applied at the factories when optical equipment was manufactured, and were also added later when instruments were returned to the factories or support facilities for maintenance, repair, and regreasing. It is quite common to see German optical equipment bearing two or more cold resistant grease markings. A reasonable estimate of the year of manufacture of individual items of German optical equipment, and their maintenance, repair, and regreasing history, can be inferred according to their cold resistant grease markings. Knowing the order and time frame in which cold resistant grease markings were introduced and used in service provides a basic time frame for estimating an item’s likely service history. |
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LUBRICATION Proper lubrication is an important part of optical instrument repair. It is a matter that has been regarded too lightly in the past. Some people believe that any grease or oil will do. Experience proves that such an idea can be detrimental to the best performance of the instrument. A lubricant may work perfectly in temperate zones, but may stiffen up to the extent of rendering the instrument useless in colder climates. Likewise, a lubricant suitable for use in temperate and cold climates may be entirely unsatisfactory for use in hot regions. The heat could soften the lubricant to the point where it will flow into other locations and impair the functioning of the instrument. A very thin film of improper grease or oil on an optical surface could cause the instrument to be useless. Since the Navy must use its optical instruments in climates from one extreme to the other, the lubricants used must perform properly under widely varying conditions. An excessive amount of lubricant is a waste, and often is as bad as, or worse than, not using enough. Where closely mated parts require only a very thin film of lubricant, an excess can introduce errors in instrument readings. The primary purpose of lubricants in optical instruments is to provide smoothness of action. Lubrication is not used to prevent wear, as is oil in an automobile engine. Thus, only a little will go a long way. The Navy buys ready-made lubricants which have been found to be satisfactory for use on optical instruments. These recommended lubricants are manufactured in different grades and are adaptable to all types of applications and temperature ranges. As an optical repairman, you should always follow the specifications in technical manuals when lubricating optical instruments. When specific instructions are not available, ask your shop supervisor for advice on which lubricants to use. Application of Lubricants To apply grease to a surface, use a round hardwood stick with a chisel point on one end. Dip the end of the stick into the grease container, and pick up a small amount of grease. Apply the grease to the surface to be greased. Smooth it out with the stick so that the entire bearing surface is covered with a thin film of grease. Fit the greased parts together and run them in. In the case of a screw, turn it in and out a few tunes to distribute the grease evenly over its entire working area. Then remove the excess grease that is forced out. Use the stick to pick off the bulk of unneeded lubricant. Wipe grease from areas where none should remain. Use a clean, lintless cloth moistened with solvent. Keep the oils in small individual instrument oil cans that are fitted with a cap for protection against dirt. Greases must be kept in clean jars or cans and kept covered when not in use. This prevents contamination by dust, grit, and dirt. All containers should be properly labeled with the name of the lubricant and also the material specification number. |
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Military and Naval Binoculars