The Al Khalid derived from Norinco Type 90IIM MBT. It was in the early 90s, when India started to test their Arjun MBT. Pakistanis looked for a MBT design that could be produced by herself.
Norinco provided their own Type 90IIM prototype, this is an MBT design which comprised many Western components, such as engine and transmission.
There were 4 prototypes for Al-Khalid development, namely P1, P2, P3 and P4.
P1 has a Chinese tank diesel engine with ZF LSG3000 transmission.
P2 has a British Perkins CV12 Condor diesel engine with French SESM ESM500 transmission.
P3 has a Ukrainian KMDB 6TD-2 2-cycle boxer engine with its own twin planetary gearbox.
P4 has a German MB871 engine with ZF LSG3000 transmission, similar to South Korean K1 MBT.
Norinco and Pakistanis planned to adopt one of the Western powerpack at first, but due to CoCom (Coordinating Committee for Export to Communist Countries) restrictions, China is under embargo, which means China would not import weapons form Western countries. Obviously P3 powerplant would be the only choice. All those descriptions on the internet about ESM500 in Al-Khalid is fatally wrong.
The Al-Khalid pre-production batch and production version all equipped with Ukrainian KMDB 6TD-2 powerpack.
It is an extremely compact design, the engine laid transversely in engine room, twin planetary gearboxes connect to both left and right end. The 6TD-2 has two crankshafts: the front one drives the mechanical supercharger, while the rear one drives the gearboxes. The cooling system covering the whole engine room, the engine itself has no mechanical connection to the cooling system, and the cooling system doesn't need mechanical drive. The cooling system based on a unique principle: exhaust gas driven ejector. The exhaust gas from the engine is injected through the outlet ducting, produce a low pressure in the outlet side, that will suck in cold air from the inlet side. This principle is also used in the T-64, T-80UD and T-84, but as far as I know, Swedish Ikv 91 is the only western tank that have similar cooling principle.
As a result, the total length of powerpack is significantly shortened, much more shorter than the European powerpack mentioned above. This leads to a spare storage room between the fighting compartment and the engine compartment. This storage is for extra ammunition and fuel, when turret points 3 or 9 o'clock, the top cover of the storage could be opened from outside, containing 10 rounds for main gun, with projectiles on the outsides, semi-combustible charges on the inside.
The data table from HIT also describe the ammunition capacity as 39+10, means that 22 ready rounds in the T-72 type carousel autoloader, 17 backup rounds scatter around the fighting compartment, and extra 10 rounds could be carried in the storage room.
The driver of Al-Khalid control the vehicle via steering wheel and an automatic gear control box. The steering wheel and gear control box send electrical signals to the computer, then computer control the hydraulic servo actuator to perform engage and disengage of brakes and clutches, making steering and gear changes, as well as adjusting the speed and torque of the engine.
Mechanically the gearboxes are nearly the same as T-64s and T-72s, but have different side reducer unit. The KMDB side reducer unit is designed as a secondary gearbox, acting like a forward-reverse selector. When both reducers were put into reverse, the vehicle can reverse using the normal forward ranges. From 1st gear to 4th gear, all could be used as high speed reverse, and that's why KMDB said this is a 7F4R gearbox system. And if only one reducer was put into reverse, the track will be driving in opposites direction, causing the vehicle turns within its tracks, a.k.a. pivot steer or center steer. T-84 also applied this driving and steering system.
The advantages of Al-Khalid's powerpack is the versatility: all 3 types of MBT in the Pakistanis arsenal, T-80UD, T-84, Al-Khalid, share the same engine and gearbox.
Or more specifically, why don't they burst? You have huge pressures behind them, they're thin and not really solidly fixed in place, and yet they are expected to stay intact - how?
Me and colli were discussing this on TS yesterday, and there's no way inertia of the firing pin could be providing meaningful support - from squinting at a pressure Vs time graph of a 30.06, and assuming the firing pin can be modelled as a piston of radius ~1mm acted on by the chamber pressure, the applied impulse is on the order of kgms-1. So that firing in should be moving backwards at a considerable velocity, given the light weight, and over the ~1millisecond of the firing process it should move several mm back - yet primers retain the impression of the firing pin after firing. The peak force applied was on the order of kN, so I'd be very surprised if the firing pin spring was providing enough of a force to resist this
pic from TankNet.
I feel uncertain whether its cannon's caliber was 140mm or not, I found a figure at the document AD-A228 389 showed behind, which label the gun as LW 120.But in many ways I've found its data in websites all considered to be 140mm.
AFAIK,the first xm291(140)demonstrator was based on xm1 tank, and the successor was the''Thumper'' which was fitted with a new turret look like the CATTB but still m1a1 hull(Maybe it was CATTB's predecessor? )
I will really appreciate if anyone have valuable information to share
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