Hmm, that seems to be a set of 3 SCR phase angle controllers rather than "normal" (to us) DC servo drives. These run from ac, so you can look and you can look but you won't find any big electrolytic caps anywhere. The 3 axis drives are those power modules in the 4th photo. You can see there are 6 of them in the 3rd photo. The drivers for the SCRs are in the 2nd photo. The date codes on the compts suggest the boards were built in 1980, so it's an old beast. Technically, they operate at 50Hz, rather than several kHz and vary the duty cycle to modulate the motor current / torque.

Bottom line is that there is no electrolytic cap(s) and the rectification is actually done by the SCRs (thyristors) and the SCRs are commutated (turned off) by the alternating voltage. The supply voltage is indeed two lots of 140V - but ac not dc. The labels on the axis / SCR controllers mention "2x140V", or 280Vac centre tapped in fact.

I think you can safely bin all the contents of the cabinet, as there is almost nothing you can reuse. Even the mains transformer is of questionable value to you. If I were you, I'd want to run the whole thing from 240Vac single phase and keep away from 415V, as there's really no benefit. You need 100Vac on the secondary, a simple bridge rectifier (600V) and an electrolytic cap rated at around 200Vdc.

The servo motors look like good machines and are indeed DC brushed motors. As I said earlier, you can get rid of the tachos and replace them with simple encoders. Indramat is nowadays part of Bosch Rexroth etc, so these drives and motors were probably designed like brick shithouses.

I'm not certain what those 3 transformer-like things are. They are labelled "Drossel" which means something like "choke", so probably line inductors to filter out the current lumps and improve the mains current waveform / power factor. Again, almost certainly of little or no value to you.