Re. the traction control system, this is from
the 'News' section of the GBRf website:
Originally built during 1976-1984, the Class 56 repower conversion will upgrade the locomotives existing Ruston-Paxman RK3 engines and control gear with EMD 12-710 Series engines, rated for EU Stage IIIA emissions certification, and updated electronic controls, based upon the world-renowned Class 66 locomotives.
...and this is what I said in post #591:
As for tractive effort and power-at-rail I assume only GBRf and Progress Rail would know, but given that the 69 retains the 56 bogies and traction motors but gains a more modern traction control system, I'd guess the low-speed tractive effort and wheelslip control would be better than a 56 but not as good as a 66.
My understanding (based partly on what was said by the MD of GBRf at a railway club meeting I attended a while ago) is that the traction control computer system is basically the same EMD/Progress Rail one that is used in the class 66.
What I've never managed to find out is if the alternator is a cl. 56 one or a new EMD one - anyone know for sure?
(The cl. 56 alternator has been mated with the EMD 645 engine before in the cl. 57 rebuilds, so it's probably theoretically possible to mate the cl. 56 alternator to the 710 engine)
AFAIK, EMD/Progress Rail have never offered Sepex DC motor control, they went directly from all-parallel connected, DC series-wound motors (with wheel slip/wheel creep control performed via electronic control of alternator excitation) - which is what the 59s & 66s have - to AC traction drives using inverters feeding induction motors, for their home market locos at least.
Probably but doubt they have creep control etc? They may have but think you need separately excited motors for it to work properly which 69s won't have.
Other things being equal, individual axle control will give you the best overall wheel slip control, because you can properly compensate for weight transfer and variations in adhesion between axles (up to the limits of the motor capability). But you don't need it just to do wheel creep control i.e. keeping the axles in the zone of maximum tractive effort, as the EMD 'Super Series' wheelslip control - which came to the UK on the 59s in 1985 - demonstrated.
www.realtimetrains.co.uk
