Israeli experience in the 1967 Middle East conflict, campaign proved that mobility was no substitute for armour protection. It therefore decided at an early stage that the main emphasis would be placed on armour, with firepower and mobility second and third priorities. Design work on the tank started as early as 1967 but detailed design work, under the direction of General Israel Tal, did not begin until August 1970. Prior to the construction of the first prototypes of the Merkava MBT a number of test rigs based on M48 and Centurion tank chassis was completed to prove the basic concept. The first prototype of the Merkava was completed in 1974. The United States contributed over US$100 million towards the development and production of the Merkava MBT. Total cost of research, development, trials and the building of the prototype vehicles was about US$65 million.

In May 1977, Israel finally announced that it had developed a new MBT called the Merkava (or Chariot) to the prototype stage and that a series production run of 40 tanks was being built. First production tanks were delivered to the Israel Defence Force 7th Armoured Brigade in 1979. The Merkava was first used in action during fighting in the Lebanon in the summer of 1982. First production Merkava Mk 2s were delivered to the Israel Defence Force in December 1983.

No production figures of the Merkava have been released but it is estimated that by early 1999 total production amounted to about 1,000 vehicles, with the current production version being the Mk 3 which became operational with the Israeli Armour Corps in early 1990.

As the Mk 1 and Mk 2 vehicles come back for base overhaul they are being upgraded with some of the components of the Mk 3, but this excludes the 120 mm smoothbore gun. In 1995, it was reported that some consideration was being given to upgrading the Merkava Mk 2 with the 120 mm gun of the Merkava Mk3.

An outline comparison of the three Marks of the Merkava MBT is shown in the accompanying Table 1.

In 1996, it was revealed that the more advanced fire-control system of the Merkava JVIk 2 had been backfitted to the earlier Mk 1 as they are overhauled. The current production model is the Mk 3. Although the Merkava has never been exported late in 1997 it was confirmed that Israel would offerthe Mk 3 in the Turkish MBT competition.

The hull of the Merkava is made of cast and welded armour with a well-shaped glacis plate with the right side higher than the left. Behind the first layer of cast armour is a space filled with diesel fuel and then another layer of armour. This spaced armour gives the tank protection from HEAT projectiles and ATGWs.

The layout of the Merkava is unconventional, with the turret and fighting compartment at the rear of the vehicle. The driver is seated on the left side of the hull, forward of the turret, with the engine compartment to his right. The driver is provided with a one-piece hatch cover that opens to the left and three observation periscopes for driving with the hatch closed; the centre one can be replaced by a passive one for night driving. The driver can reach his compartment through the main crew compartment as the backrest of the driver's seat folds forwards.

The Teledyne Continental (now General Dynamics Land Systems) AVDS-1790-6A V-12 diesel develops 900 hp and is coupled to an Allison Transmission Division of General Motors CD-850-6BX transmission. The engine is in fact a more powerful version of the engine fitted to the M60 and M60A1 MBTs and the transmission is also similar to that installed in these tanks. Access to the engine compartment is via two flaps which are opened by springs after the locks are released. The engine can be replaced in the field in about 60 minutes. The air-cooling filter vent is positioned in the upper part of the hull, forward of the driver's seat, with the outlet being located on the opposite side. The exhaust outlet is on the right side of the hull, above the skirting plates over the second roadwheel.

The wedge-shaped turret, which has been designed to accept either a 105 mm (M68) or Israel Military Industries' 120 mm gun, is cast with a welded front. It has a small cross-section and a large overhang at the rear. The radios and hydraulics are mounted in the turret bustle. The commander is seated on the right side of the turret with the gunner seated forward and below the commander. The commander has no cupola but is provided with a hatch cover that opens to the rear and five periscopes for all-round observation. The commander's hatch can be raised manually giving direct all-round observation while retaining full overhead protection. Mounted forward of this hatch cover in the roof of the tank is a sight that can be traversed through 360°, with a zoom magnification of from x4 to x20. The rotating head of the commander's periscope is linked to the turret traverse system by a counter-rotating device. The gunner's optics are in the forward part of the turret roof and right-angled ribs in front of the optics stop shell splinters and small arms fire from damaging them. The gunner's periscope has magnifications of x1 and x8 and incorporates a laser range-finder. The loader is seated on the left rear side of the turret and is provided with a single-piece hatch cover opening to the rear and a single periscope.

There are three hatch covers in the rear of the hull: the left one gives access to the batteries and the right one gives access to the NBC pack. The centre one is a two-part door, the upper part opening upwards and the lower part downwards, through which ammunition or wounded can be loaded. This hatch can be opened from the outside but locked from the inside. A 60 litre water tank is provided above the rear hatch. The infantry telephone is mounted at the rear of the hull on the left side. Many Merkava MBTs have been fitted with closely spaced chains with ball ends around the lower part of the turret bustle. These detonate HEAT projectiles before they can hit the turret ring.

The Mk 1 Merkava has six 790 mm Centurion-type rubber-tyred roadwheels either side with the drive sprocket at the front, idler at the rear and four track-return rollers. Each roadwheel is suspended by a separate helical spring with suspension arms for two roadwheels, each caged in a housing. The first, second and fourth track-return rollers support the inside of the track only. Urdan Industries has developed a new roadwheel for Merkava and Centurion MBTs which has the same weight but twice the life.

A white light and an infrared driving light mounted on either side of the glacis plate can be folded down in action to avoid damage from shell splinters and small arms fire. The 1 kW searchlight is mounted vertically in the bustle under armour protection to the rear of the loader's position and is controlled by the tank commander. The Merkava is equipped with an NBC system and a Spectronix explosion suppression system. This was not fitted to original Merkava MBTs but is now standard on all new production vehicles and has been backfitted to older vehicles as they return for overhaul.

Main armament is a standard 105 mm M68 rifled tank gun fitted with a thermal sleeve, manufactured in Israel by Israel Military Industries and also fitted to most other Israeli tanks. It has an elevation of +20° and a depression of-8.5°. A travelling lock is provided for the 105 mm gun on the right side of the glacis plate. The Merkava carries a total of 62 rounds of 105 mm ammunition of which six are stowed below the turret ring for ready use and the remainder in the hull rear, 12 in two-round containers and 44 in four-round containers. No ammunition is stowed above the turret ring or in the hull front and all ammunition is in special containers. In addition to the standard 105 mm HEAT and HESH rounds the gun will fire an APFSDS-T round called the M111 developed by Israel Military Industries, which is claimed to be superior to the American M735. More recently, Israel Military Industries has introduced anew 105 mm APFSDS-T round called the M413 which has a muzzle velocity of 1,455 m/s when fired from an L7/M68 gun with a maximum effective range of 6,000 m.

The 105 mm gun is fitted with a thermal sleeve designed and built by Video Industries and this is also fitted to Israeli M48, M60 and Centurion series MBTs. This eliminates most of the error caused by barrel bending due to sun, wind, rain and other effects and improves first round hit probability.

A 7.62 mm machine gun is mounted coaxially to the left of the main armament and a similar weapon is mounted at the commander's and loader's station; these weapons can be lowered to reduce the profile of the Merkava.

The coaxial machine gun is fed from a 2,000 round continuous belt which is between the plates of the spaced armour. The machine guns are 7.62 mm MAGs, manufactured under licence from FN Herstal. Some Merkavas have been observed with a 12.7 mm M2 HB machine gun over the gun barrel. A 60 mm Soltam Commando mortar is carried by the Merkava for which 30 mortar bombs are stored in a compartment in the turret rear. This mortar fires high-explosive, smoke and illumination bombs and helps conserve 105 mm ammunition.

During the 1973 Middle East war many Israeli tanks ran out of ammunition and so the Merkava has been designed to carry a large supply in the rear of the hull. The Merkava can also be used as a command post with the ammunition supply containers removed. By reducing the ammunition load the Merkava can also carry troops, for example 10 infantry can be carried by reducing the ammunition load by 45 rounds or a commando squad of three together with their radios if the ammunition load is reduced by 25 rounds. It must be emphasised that the ability to carry infantry is only an option for use in special circumstances as the infantry have no vision devices at all.

The Merkava has a digital fire-control system designed by Elbit Computers Limited of Haifa and a laser range-finder which can be used by the commander or gunner. This fire-control system is called the Matador Mk 1. The laser range-finder is manufactured by ELOP Electro-Optics Industries and feeds information into the computer. The system is built around a central processing unit and consists of operation units, control and feedback servo loops and sensors. The system includes three operation units, gunner's, commander's and loader's. The gunner's is the main unit and provides all manual inputs necessary for ballistic computation. It also includes a logistic panel which enables system boresighting and system BITE, as well as the display of preselected inputs. The unit also includes the following manual inputs: type of ammunition (six types) and recoil compensation insertion for each type of ammunition, in elevation and deflection. The commander's unit provides a readout of the system's display, range and ammunition inputs. The loader's unit provides ammunition inputs.

The control loop transfers the computer superelevation information to the hydraulic gun elevation drive and the ballistic move drive. In addition, deflection data is transferred to the moving graticule. The feedback loop ensures that the actual superelevation and graticule deflection data are identical to the computed data and will correct the error accordingly.

The system includes automatic sensors, a laser range-finder, a turret cant angle indicator and a target angular velocity sensor. Optional sensors include crosswind velocity, charge temperature, barrel bend and ambient air density.

Manual operation of the electrical system, if the computer fails, is made possible with a handwheel drum and mounted scales, connected to the mechanical gearbox, to give elevation angle compensation and range to target for all types of projectiles. The commander can, if required, take over control of the main armament and fire the gun. The main armament is stabilised in both planes as US HR Textron Incorporated stabilisation system is fitted as standard. This is manufactured under licence in Israel by PML Precision Mechanism Ltd.

• 155 mm Self-propelled Gun

Details of the Soltam Slammer 155 mm self-propelled howitzer based on a Merkava chassis are given in the Self-propelled guns and howitzers (tracked) section under Israel. This system is still at the prototype stage and by early 1991 two prototypes had been completed.

Some Merkava MBTs have attachment plates underthe hull front to enable them to be fitted with Israeli-designed and produced mineclearing roller equipment and dozer blades.

Platoon communications versions of the Merkava are also in service; these have additional communications equipment and an additional antenna.

Late production Merkava Mk 2 MBTs were built with bolts and fastners for the attachment of a dozer blade or mineclearing systems. Early vehicles were backfitted with these attachments.