Armored engineer machine

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Armored Engineer Machine (GPM) was the name given to two prototypes of a new engineer tank for the Bundeswehr . At the end of the 1960s, it was decided to replace the previous Pionierpanzer 1 with a vehicle that was supposed to better meet the demands of the troops, and in 1972 work began on developing an improved successor. The companies EWK Eisenwerke Kaiserslautern (now General Dynamics European Land Systems GmbH , a subsidiary of General Dynamics ) and MaK Maschinenbau Kiel (now Caterpillar Motoren GmbH & Co. KG, a subsidiary of Caterpillar Inc.) each received the order to build a prototype.

Development history

Armored pioneer machine prototype MAK, loaded with railway
Prototype EWK armored engineer during a troop test in January 1977

In the period from 1969 to 1973 the Federal Office for Defense Technology and Procurement (BWB) defined a catalog of requirements for the future design of a pioneer tank on behalf of the Bundeswehr. In addition to the recovery of damaged vehicles, pioneering work on bank banks such as the creation of entrances and exits on steep and muddy bank zones as well as working in flowing waters including underwater work were required. Two armaments companies - Maschinenbau Kiel (MaK) and Eisenwerke Kaiserslautern (EWK) - each built a prototype (PT). The Jung Jungenthal company carried out the tub modifications for both manufacturers.

After completion, the troop trials began by the Army Pioneer School and Technical College for Structural Engineering in Munich (moved to Ingolstadt in January 2009 - now back to the Pioneer Training Center) and by the Bundeswehr test center 51 in Koblenz. The overuse and thus excessive wear of the Leopard 1 chassis quickly became apparent . The pioneering equipment increased the weight to more than 50 t. The EWK prototype 1 was significantly overloaded with a combat weight of 57 t. The PT 2 excavator system in the slewing ring also overwhelmed the construction of the tub.

In 1977 the development was stopped for several reasons: the hydraulic system was complicated and difficult to maintain, several assemblies were immature, the concept appeared ergonomically unsatisfactory and ultimately too expensive. Since then, prototype 1 has been in a depot of the defense technology study collection in Koblenz . Prototype 2 served until 1980 without pioneering equipment as a test vehicle for recovery and winch equipment and has since been part of the former MaK collection in Kiel.

The knowledge gained led to the Dachs Pioneer Tank , which is not a new development, but an improvement on the previous Pioneer Tank 1 (PiPz 1). The most striking thing about the roof is the telescopic excavator arm of the GPM EWK, which had proven to be the only convincing unit and which replaced the crane arm of the PiPz 1 in individual equipment. The idea of using the hull of the Leopard 2 in a possible series production was implemented in the later Kodiak pioneer tank by armaments companies at the beginning of the 21st century. In 1974, an attempt at bilateral cooperation with the British Combat Engineer Tractor FV 180 tank engine, which was also being developed, failed .

technical description


GPM prototype EWK after deep wading

The prototype from EWK relied on two telescopic arm excavators , which were connected to the chassis at the front left and right by means of turntables. During the march, the two excavator arms were put down to the rear. The crew found their place between the arms and sat in a tandem arrangement. It consisted of the driver and operator for the right arm, the excavator operator for the left arm and the commander . If necessary, however, the excavator operator could control both excavators, as it was necessary that both arms were operated by one person when overcoming obstacles due to the synchronization.

The dredging capacity of the two backhoe buckets totaled 170 m³ / h. The swivel range was 195 ° on each side, the elevation range was 60 °. The maximum digging depth was reached at 6 m, whereby the excavator operator could no longer see anything from a depth of 4.50 m and had to work by feeling. With the help of the excavator arms, the crew was able to negotiate gradients of approx. 85% in reverse. The recovery thread had a tensile force of 350 kN. The blade came from the Pionierpanzer 1 and was equipped with a cutting angle adjustment. This allowed the shield to be tilted and thus better adapted to the existing soil conditions. The clearing capacity was 300 m³ / h.

The hydraulic system worked with six pumps, two hydraulic tanks and a heat exchanger for an output of 176 kW. They took care of the excavator, the shield and the winch equipment. The units were operated here via indirectly manually / hydraulically controlled valves (so-called pilot-controlled valves). The curb weight reached 51 t.

A machine gun on a rotating ring mount was available to the commander for self-defense .


MAK armored engineer during a troop test in January 1977

Maschinenbau Kiel used the slewing ring of the Leopard 1 battle tank turret for their design. The frame arm articulated excavator from Orenstein & Koppel was installed in a rotating turret and had a swivel range of 360 °. In the marching position, the arm was swiveled backwards and folded down on the engine cover plate. The division of the crew was similar to that of a main battle tank. The commander and excavator operator were accommodated in the tower, while the driver was seated in the tub. To save weight, the engine cover plate was made of aluminum. The total weight was 55 t. The pulling force of the recovery thread reached 350 kN in a single pull.

The dozer blade could be divided in the middle and could be folded out to the left and right in order to throw off the material to the side - but this had turned out to be impractical. As with the PT 1, a cutting angle adjustment was built in. In addition, the sign was widened to 3.75 m. The clearance rate was 300 m³ / h.

Compared to the PT 1, the maximum digging depth of the excavator shovel was 5 m. Due to the fact that the excavator shovel could reach under the chain from the side, it was theoretically possible to knock the vehicle over on one's own.

A serious disadvantage of this vehicle was the driver's hatch that could be opened upwards. When the tower was in the 11 o'clock position, it could no longer be opened and the emergency exit hatch could not be reached by the driver either, as it was blocked by a hydraulic block.


  • FM by Senger and Etterlin : Tanks of the World 1983. Arms and Armor Press, London 1983, ISBN 0-85368-585-1
  • Template Technical regulation: Armored engineer machine. GPM 1 and GPM 2, part 22 . BMVg 1974
  • Stefan Marx: Army pioneer tank 1965-today , Tankograd military vehicles special No. 5008, Tankograd Publishing (2005)