The Israelis have long sought to manufacture as much of their military hardware as possible at home.There are a couple good reasons for this. First, in the event of an arms embargo, they won’t find themselves without the weapons they need to fight. Having faced more than one embargo, they are somewhat wary of placing any faith in anybody outside Israel. Second, as an export industry, it can be very profitable, once they have an established production base. There are more than a couple countries that have no great love for Israel but have ended up buying military hardware from them.
One area the Israelis really wanted to establish some independence in was making tanks. A modern tank takes a lot more work to make than you might think. The armor itself is difficult to produce. You also need powerful engines, the delicate machinery to operate the turret, the precision milling to make the main gun, the specialized electronics and optics for the fire control system and an industry to make the ammunition.
After the 1973 Yom Kippur War, Israel got serious about manufacturing their own tank. And based on the heavy casualties in tank crews during that war, one of the objectives was to make crew survivability a priority (the US Army’s design of the M-1 tank was also heavily influenced by the same factors).
The result of the development was the Merkava tank. The Merkava was a little unusual in several ways. Unlike just about every other main battle tank in the world, the Merkava had its engine mounted in the front, pushing the turret towards the rear. This provided an extra degree of protection in that if a round penetrated the front armor, it would still have to go through the engine to get to the crew compartment. And because the crew compartment was at the rear of the vehicle, you could put a small entry to the vehicle in the back. By removing some of the ammo racks, you could provide space for a couple infantrymen or extra radios and operators for a unit commander or even put in medics and litters to use the vehicle as an ambulance. Finally, the wedge shaped turret was designed to cause most shells striking it to ricochet rather than penetrate.
Over the years, the Merkava has been developed in four main versions. Most of the early versions are being withdrawn from service. Some thought was given to converting them to armored personnel carriers, but as of 2008 the decision was made to build new APCs based on the Merkava 4 design.