The 65t Merkava 4 is the most recent variant of the Merkava tank that has been in development since 1999 and began operational training with the Israel Defence Force in July 2003. The upgrade’s development was announced in an October 1999 edition of the Bamachaneh (“At the Camp”) military publication. However, the Merkava Mark III remained in production until 2003. The first Merkava IVs were in production in limited numbers by the end of 2004. The Merkava 4 is slightly larger than the Merkava 3 Baz, which has been in service with the IDF since 1990. The Merkava 4 is not offered for export but the systems and components are exported.
When ammunition is unloaded the tank can carry up to 8 dismounted soldiers or 3 stretchers. Troops enter and leave the vehicle through the rear hatch. Removable modular armor, from the Merkava Mark IIID, is used on all sides, including the top and a V-shaped belly armor pack for the underside. This modular system is designed to allow for damaged tanks to be rapidly repaired and returned to the field. Because rear armor is thinner, chains with iron balls are attached in order to detonate projectiles before they hit the main armored hull.
It is the first contemporary tank with no loaders hatch in the turret roof, because any aperture in the turret roof increases risk of penetration by ATGMs. Tank rounds are stored in individual fire-proof canisters, which reduce the chance of cookoffs in a fire inside the tank. The turret is electrically-powered (hydraulic turrets use flammable liquid that ignites if the turret is penetrated) and “dry”: no active rounds are stored in it. Some features, such as hull shaping, exterior non-reflective paints (radar cross-section reduction), and shielding for engine heat plumes mixing with air particles (reduced infrared signature) to confuse enemy thermal imagers, were carried over from the IAI Lavi program of the Israeli Air Force to make the tank harder to spot by heat sensors and radar.
The Mark IV includes the larger 120 mm main gun of the previous versions, but can fire a wider variety of ammunition, including HEAT and sabot rounds like the APFSDS kinetic energy penetrator, using an electrical semi-automatic revolving magazine for 10 rounds. It also includes a much larger 12.7 mm machine gun for anti-vehicle operations (most commonly used against technicals).
The Mark IV has the Israeli-designed “TSAWS (Tracks, Springs, and Wheels System)” caterpillar track system, called “Mazkom” by troops. This system is designed to reduce track-shedding under the harsh basalt rock conditions of Lebanon and the Golan Heights.
The model has a new fire-control system, the El-Op Knight Mark 4. The computer-controlled fire control system can acquire and lock onto moving targets, even airborne helicopters, while the tank itself is on the move. It includes line-of-sight stabilisation in two axes, a second-generation television sight and automatic thermal target tracker, a laser range finder, an improved thermal night vision system and a dynamic cant angle indicator. An Amcoram LWS-2 laser warning receiver notifies the crew of threats like laser-guided anti-tank missiles, which can fire smoke grenade launchers to obscure the tank from the laser beam. Electromagnetic warning against radar illumination is also installed.
The tank carries the Israeli Elbit Systems BMS (Battle Management System; Hebrew: צי”ד), a centralised system that takes data from tracked units and UAVs in theater, displays it on color screens, and distributes it in encrypted form to all other units equipped with BMS in a given theater. The Merkava IV has been designed for rapid repair and fast replacement of damaged armour, with modular armour that can be easily removed and replaced. It is also designed to be cost-effective in production and maintenance; its cost is lower than that of a number of other tanks used by Western armies. The engine can be replaced in field conditions within 30 minutes. The tank has a high performance air conditioning system and can even be fitted with a toilet for long duration missions.
The Merkava Mark IVm Windbreaker is a Merkava Mark IV equipped with the Trophy active protection system (APS), designated “Meil Ruach” (Hebrew: מעיל רוח; “Windbreaker” or “Wind Coat”). The serial production of Mark IVm tanks started in 2009 and the first whole brigade of Mark IVms was declared operational in 2011. The Trophy APS successfully intercepted rocket-propelled grenades and anti-tank missiles, including 9M133 Kornets, fired by Hamas before and during Operation Protective Edge in 2014. Not a single Merkava tank was lost in combat operations in 2008 and 2014—despite the war in 2014 being a costly one for the Israeli Defense Forces. The system also notifies the tanks crew of the location that the projectile came from, allowing them to fire back quickly. It can transmit the coordinates to nearby ground and air units through the Tzayad battlefield management system. All friendly units in the theater are instantly apprised of the enemy’s position making escape and evasion difficult.