The M1 Abrams tank uses a special turbine engine that makes it faster and lighter than tanks that use diesel engines.
This engine can also run on a variety of fuels and has a high torque advantage. The tank's armor has evolved over time and now uses a combination of ceramic and metal plates to protect against projectiles.
The armor also includes a layer called a spall liner that limits damage caused by shock waves. Finally, the M1 can use reactive armor tiles to further protect against shaped charges.
The M1 Abrams tank uses a high-speed turbine engine that is lighter and faster than diesel engines.
The engine has a high torque advantage and can run on many fuel types.
The tank's armor uses a special ceramic and metal composite that is highly effective at protecting against projectiles.
The armor includes a spall liner that limits damage from shock waves.
Reactive armor tiles can be added to the tank to protect against shaped charges.
The exact details of the armor's composition and thickness are classified
The M1 Abrams has two smoke generating systems - engine exhaust injection and grenade launchers.
The tank has a dedicated crew member, the loader, for manual loading.
German Rheinmetall RH-120 is used in the tank's 120 mm guns.
The M1 Abrams weighs between 52 and 68 tonnes.
The tank has a torsion spring suspension system.
Hydrogas suspensions were considered during development.
The recuperator is a giant heat exchanger that lowers the heat signature of the exhaust and increases fuel efficiency, transferring more heat energy back into the engine instead of losing it to the atmosphere.
The M1 Abrams is still a thirsty machine, even by tank standards.
The turbine engine uses twice the fuel as a comparable diesel per kilometer.
The armor installed on the M1 Abrams has evolved and changed over the last four decades.
The exact details of its thickness, location, materials, and layering are classified for obvious reasons.
Early M1 variants used a type of composite ceramic armor called Chobham.
Chobham derives much of its ballistic resistance from an extremely hard and light ceramic layer.
Hardness in material science is a measure of a material's ability to resist localized deformation, like a scratch.
Diamonds are extremely hard, and because of this, industrial diamonds are coated onto cutting tools to help them cut through materials without being eroded themselves.
A hard material can scratch and erode a softer material.
Hardness can be measured with a Vickers hardness test, which pushes a pyramid-shaped diamond into the material.
The hardness is then calculated by dividing the force applied resulting surface area of the indentation.
The rolled homogeneous armor steel of World War II has a Vickers Hardness of 380, high carbon hard steel is about 550, while a ceramic like silicone carbide offers hardness 5 times greater, up to 2500.
Ceramics are extremely brittle, and they shatter into a million pieces with little force.
Ceramic composite armor combines ceramic and metal to create a highly effective armor system.
The ceramic is placed on the outside of metal plating, acting like an extremely hard outer shell.
When a round strikes the armor, the compressive strength and hardness of the ceramic coating causes the round to fracture and break apart, at the same time ceramic coating begins to fracture and fragment, spreading the energy of impact across a larger area which is then absorbed by the tougher metal plate backing ceramic.
Ceramic armor performed even better when placed under compression.
This can be achieved by simply adding a face plate and bolting the two pieces together.
Embedded compressed ceramic armor can defeat kinetic energy weapons.
Projectiles don’t necessarily need to penetrate every layer of armor to be deadly.
If they hit with enough force, the kinetic energy can simply transfer through the material as a wave and cause material on the inside of the tank to turn into deadly shrapnel inside the crew compartment.
This is called spall.
High explosive squash heads are made from soft plastic explosives that spread out over the armor's surface.
The spall liner is a ductile and dense material that limits spalling.
For early M1s, this layer was typically composed of lead, but beginning in 1988 certain M1A1s began to be upgraded with depleted uranium spall liners.
And all new M1A2s were assembled with depleted uranium liners.
Modern composite armor makes it difficult for this shock wave to transmit through the material, and a spaced layer with an air gap can defeat this squash head munition completely.
With the development of depleted uranium rounds, the 105 mm gun on the previous generation M60 tank was viewed as inadequate to deal with any Soviet armor.
The US allies, like Germany, did not want to use depleted uranium rounds due to ethical implications. They were moving towards using 120 mm cannons with the British Chieftain tank using the Royal Ordinance L11 and the German Leopard 2 Rheinmetall RH-120.
This posed a problem for NATO’s goals of standardizing wherever possible to optimize logistics.
With ammunition factories across NATO countries producing the same ammunition, this ensured ammunition could not only be shared but also manufactured as close to the frontline as possible.
The M1 Abrams uses 120 mm guns that are German Rheinmetall RH-120 manufactured under license in the US.
Hydrogas suspensions are much smaller, lighter, and easier to service than torsion bars.
The road wheel has an attached axle pivot arm, which in turn turns a crank and con-rod piston.
This piston connects to the hydragas suspension cylinder.
The first chamber is filled with fluid, typically oil.
The oil is relatively incompressible and provides marginal spring force, but this chamber has a damper valve that serves to restrict the transfer of fluid between this chamber and the next, which contains a floating piston with compressed nitrogen gas on the other side.
This provides resistance to ensure the road wheels stay in contact with the ground but also dampens out vibrations.
Hydrogas suspensions were considered for the M1 during development, but it was a relatively new technology at the time, and so torsion spring was chosen.