Transmission is more critical than the engine, but still big!
S&T Dynamics’ automatic transmission failed in the durability tests six times for the K2 Tank.
A tank transmission must run for 320 hours without defects.
I'm more conservative, but lets see..
Of the 6 failed tests, The first 3 (main pump drive bearing fracture caused by faulty assembly, main housing fracture caused by manufacturing defect, damage to planetary gear caused by faulty heat treatment) were clear-cut technical failures induced by reasons imputable to S&T. The reason for the 4th failure is hard to attribute. 5th test failed due to the testing equipment, which is not a transmission related problem. Reason for the 6th failure has not been determined at the time due to disputes between S&T and DAPA. There's a chance it's clarified now but it hasn't been published yet regardless.
Moreover, ever since the testing campaign was suspended, S&T introduced new core components to the transmission, including those replacing parts from German suppliers. Testing would need to be done again regardless.
This issue was discussed here and the situation of Korean transmission was explained by
@Baljak in detail. Just do an “Altay Transmission- Baljak” search and you will see the explanation.
According to
@Baljak this was most probably a defective part that needed to be redesigned and remanufactured. And that this is now done. So the new transmission should work.
Apparently according to
@Baljak , the MTU engine is a short stroke engine and the Doosan engine is a long stroke engine and has higher torque at lower revs. This introduces unforeseen stresses on the transmission. That may have been the underlying problem in the transmission coupled to a part‘s design defect.
Or it will have an internal limiter for acceleration
defencehub.live
Yes, it is true that MT883 is a short stroke engine whereas DV27K is long stroke. More to be specific, MT883 has a bore width of 144mm to the stroke length of 140mm and is slightly more short stroke than a square engine. DV27K on the other hand is you typical long stroke diesel engine with a bore width of 138mm to stroke length of 150mm. This in part is due to their history of license producing as Daewoo MAN, as well as their past portfolio of developing heavy duty engines based on those MAN engine designs.
DV27K with its long stroke cylinder design has a very comparable/slightly better torque curve compared to the 501K variant of MT883
These are torque and power curve comparison created by Boltzman a forum member of Korean forum Bemil, based on the officialy published torque and power curves. As you can see, the difference in acceleration speed between the two isn't simply because one's better than the other. It is true though, that the short stroke MT883 will have better throttle response than the DV27K. For that reason the DV27K is already in service with the Korean Army for years. They are also planning to develop a variant of it for the amphibious assault vehicle, similar to the cancelled EFV, under development.
Anyways, we'll know how the S&T EST15K transmission will do in Altay trials. What's concerning though is that I've heard from one of the forum members that Türkiye isn't testing the newest variant with new components, but the older variant. I'm not sure how credible such claim is though. There's also the possibility that the HSWL 295 will be used for the 4th batch of K2 for the Korean Army. That possibility is currently being assessed by DAPA and others involved with the program.
