The Merkava has its engine in the front and this allows it to put a big chunk of metal inbetween the crew and the most likely direction of fire as well as making it possible to have rear doors. Rear doors make it easier and safer to enter and exit the vehicule and it makes it possible to carry more equipment and even infantry.
So, why don’t most tanks do this?
The only good reason I can think of to have th engine in the back is equalizing ground pressure. Armor weighs the most at the front, the turret’s typically in the middle so putting the engine in the back would distribute the weight about as evenly as can be. Since tanks are all about heavy weight and its ground distribution, that might outweigh the advantages of having a front engine.
Engine != armor. Cops who are under fire are trained to take cover behind one of the front wheels because an engine block and a bunch of sheet metal does OK against bullets, but it’s definitely not the same thing as several inches of carefully engineered armor.
With incoming fire, if I have a choice to be behind an engine or a plate of armor, I would much rather be behind armor.
In the Merkava, there’s plenty of armor and engine up front. Any frontal hit that penetrates the armor will destroy the engine, but probably not harm the crew. It was designed with crew survivability as the absolute top priority.
However, that probably adds a lot of engineering problems. A big tank engine needs big air intakes and exhausts. It also needs to be easily accessible for maintenance. If you put it up front, you’ve got to route the intake and exhaust to the back of the tank so you don’t add any vulnerable points to the front. You also have to lift up big slabs of frontal armor to access the engine, again without adding vulnerable points. It’s possible, obviously, but it’s probably easier and cheaper to put the engine in the back.
Possibly because the drive sprocket for the tracks is usually at the back of the tank, and having the engine in the back simplifies the transmission. I’m not sure if there’s a reason for always having the drive sprocket at the back, although it would seem to me to make more mechanical sense that way.
WAG. It’s a lot easier to seat a driver with better visibility if he doesn’t have an engine in the way. The drivers seats tend to be low so they are out of the way of the turret mechanics and crew. If the driver has to be higher in order to have a line of site not blocked by the engine he’s makes the engineering for the other functions harder to fit in.
I’m sure arguments and designs can put people and engines just about anywhere in the tank but the simple reason for anything is that’s where the engineers like to put them. Our tanks are the best in the world building and improving on older designs. Engine placement hasn’t appeared to be a change that needed to be addressed, if it ain’t broke don’t fix it.
Also bear in mind that sticking up on the battlefield is a good way to get your fool head blowed off, even if you’re a tank. Lower silhouette is better.
the green hornet’s car is the only exception i know but vehicles with weapons have difficulty bringing their weapons to bear when the engine is up front. you have armored cars with engines out front and a 90mm gun on a turret but the result is a high profile. the rear portion is the logical place to keep your engine and ammunition.
the engine placement depends on the purpose of the vehicle. the israeli tank (a sleek looking peice of equipment) designed explicitly for crew survivability(rear escape hatch). amored troop carriers such as bradleys and M113s (ok not tanks but the illustrate the point) you need the room for the troops, the M1 Abrams, rear engine because it uses a turbine engine (think aircraft engine) which puts out a LOT of heat. you want to exhaust that heat to the rear without having to channel it past your fuel and crew (I beleive the israelis use a conventional piston engine that exhausts to the side). on a tactical level, rear turbine engine and exhaust is part of why the Abrams is also know as “silent death” or “whispering death” plus, I’d rather have the engine in the back to stop bullets if needed since thats where the armor is always thinnest. drive sprockets are put on the end where the engine is btw regardless of which end.
