I've got some experience with Tier 4 Final from AGCO, they where the first one in the AG business that used to start with Adblue (Ureum?! called in the States)
Tier 4 Final is usely accomplished by the two most common technics,
- engine with DPF (diesel partical filter) and EGR (exhaust gas recurculation)
- engine with Adblue and SCR catalysator
- engine with both the systems
DPF+EGR: the EGR was already on the Tier 3 versions, and they reprogrammed the EGR settings, and with the DPF they can "catch" the little particals.
this DPF will fill it self with the cole particals and then the machine will go in re-generate mode.
The engine will give some more end-injection so it will give more exhaust temperature.
the temperature needs to rise above a certain temperature and then it can start burning these cole particals to even smaller parts and these will pass true the filter and ash will stay behind.
after a couple 1000 hours (4000-7000 is what i hear in the field, depending on engine load etc.) this filter will be filled with ash and then you need to replace it or you need to let it clean out.
this cost around €2500,-, replacing could cost you 2x more...
the biggest issue this DPF has is that it needs to regenerate.. so if you use your machine and its gonna re-generate some times it will drop engine performance (some brands do this) and some brands you even need to stop doing your work and idle for the re-generation (these are usely the Tier 4 and not the final ones)
Adblue:
with Adblue they "clean"the air inside off the exhaustmuffler/catalysator so the engine can perform a bit more like it used to do and usely you will see the engine is a upgraded Tier 3 without the EGR and other three hugger stuff.
Technicaly they should use less fuel cause they don't need to re-generate and they don't burn the used exhaust fumes , but the SCR catalysator needs to reach a certain temperature to work correct so if it's not hot enough under his workload then it can also heat itself up by using a bit more end-injection. how ever you won't feel the difference.
Now with the T4 Final, some brands have chosen to use both technics, cause the need to make sure the engine emisions stays within the set limits for a couple of years (i thought 5?) and with the combination these limits are easier to maintain. And the limits are so difficult to reach.
EGR+DPF:
+ no need for Adblue
+ a bit less electronics without the Adblue system and SCR (not that the EGR control isn't controlled by electronics!)
- EGR Valves are the ****s..
- Usely the EGR after cooler will tend to leak engine coolant.
- some brands use VGT turbos which can cause some issues under certain workloads.
- when your engine starts to have higher oil consumption this oil will be caught in the DPF and will burnout the ceramic material when the DPF will re-generate.
Adblue+SCR:
+ No EGR and aftercooler
+ engine perfomance better.
- a bit more electronics and component do to the Adblue.
- Adblue is quite aggresive so what for it.
- you need to fill up also the adblue
and when they use both systems then its usely a mix off above..
a plus point off having a T4 final is that they learned a lot off the T4, Volvo had big issues with their G series and with the H they fixed a lot off those problems!
what i like on a Cat machine, the whole Muffler/catalysator and DPF is in one unit, i spoke with a Cat mechanic and they sad these units where pretty much the same on a lot off their equipment.
biggest problem is when you take off one wire, the importer from here even needs to ask Caterpillar for a special code so he can clear the fault codes...
but i think there are a few Cat guys down here that know how that works.
so that shows how complicated these electrics can be and what it could be when the wiring is getting older.. but i think thats gonna be a common problem on all the brands..
i hope i helped you out a bit, feel free to ask questions.
