On a loco like a Gronk - which isn't very big - much easier to mount the traction motors on one axle and link the other wheels with connecting rods, than try to fit six itty-bitty motors in. The 363 has a hydraulic transmission and, again, it's much simpler just to have it drive one axle and use connecting rods.
Basicly the reason & benefits are said by leadcatcher & solicitr. Here is just 1 traction motor to maintain (or at least not for every wheelset a motor), and for shunters with short wheelbase you save space this way. Well the contra: not every wheelset has a traction motor to produce power, why you are limited in tractive effort or speed. Thats from the 08:
In case of the 08 yes, you can even switch them from parallel to serial, dtg has modeled that. In series the max. Speed shouldnt exceed 10mph and 400 amp. Wish they would upgrade the 09 as well.
Where did you find these great diagrams? Are there others available? I'd like to be able to read the captions. Thanks for posting them.
But then you only need the axle that has the motor, ahs either itis to only set of wheels that actually provide power, so why link the others, it the end it would just lower the available power, as some of it is needed to make the piston bar move, and the others wheels, where if they were free moving it would leave even more power to the wheels it is actually applied to
Grip Two wheels driving means power is only being laid down by those wheels, if they slip you have no power. If you have six wheels operating in unison then much less likely to slip
Its about traction force and the way its being brought on track. 3 axles having traction force is more efficient and more powerful than only 1 axle powered and the others left out.
This is why C-C six-axle, six-motor arrangements are considered preferable for road engines to B-B four axle setups (compare the EMD SD and GP series), and why back in steam days heavy freight locos used more, smaller-diameter driving wheels compared to similarly-sized passenger engines. Or consider why off-road trucks have 4-wheel drive.
Another reason behind this decision is that the wheel diameter was also used "as a gearbox" smaller wheels with the same transmission means a lower gear ratio, so more torque but less top speed, with steam locomotives that often was the easier method to change the gear ratio of the locomotive. Don't quote me on this but I believe that even today high speed trains generally have bigger diameter wheels to limit stress, which AFAIK mostly depends on RPM (Again, I'm not sure)
They are called Eagle Cutaways, and i found them randomly on flickr. You dont need an account, the profil is named "ausdew", he has a trillion of those about everything, not just trains. I dont know where they are coming, but somebody put huge effort into all that. Here few more: Cl. 31: Cl47: Cl.52:
Though there are more exceptions with modern traction equipment, meaning there is no solid correlation between wheel diameter and speedtractive effort gearing, there seems to be some trend. For example, the high speed BR 101 has larger wheels than the TRAXX locomotives, but then again, both freight and passenger TRAXX locos have the same wheel diameter, even though one is geared for speed and one for TE (admittedly their speed and TE numbers aren't that different though). On the ICE 4 another interesting trend becomes apparent. Powered bogies have larger wheel diameters and the non powered ones have smaller bogies. IIRC that's because the larger powered wheels help with speed, but smaller wheels increase passenger comfort (much like with cars). So yeah, there is some correlation still between wheel diameter and speed/tractive effort, but not nearly as much as with steam engines.
The Eagle was a British comic paper published 1950-69 (revived briefly in the 80s) and aimed at boys (those were sexist times ) aged about 10-16. As well as these amazing cutaway drawings of all types of technology, it was perhaps best known for Dan Dare, (space) pilot of the future, and his battles with the Mekon. Lots more here: https://en.wikipedia.org/wiki/Eagle_(British_comics)
