What kind of motor is this?

[Lucien Nunes]

Interesting old machine still in use. I've talked about similar motors before but not this type AFAIK. To the trained eye, the shape of this one is a giveaway, from which you can identify its maker and the technology it uses, and probably say something about the available electrical supply. In any case the shape should tell you something. Note that the bare aluminium covers are non standard, these would normally be steel mesh vent grilles.

 

[Simon47]

Standard setup with lineshafts is to have dual.pulleys on the driven end of each take off belt. One pulley is free running on it's shaft, the other drives it. So starting/stopping machines is a matter of throwing the belt from one pulley to the other - where it will stay on it's own thanks to the crowning on the two pulleys. In posh safety concious setups there may be a mechanism for doing it, otherwise it's done carefully with a stick to push on the side of the belt

 

[Lucien Nunes]

A.k.a 'fast and loose' pulleys, fast as in fixed rather than quick.
As Simon says there were a number of different arrangements for starting a motor manually. Resistance starters, such as a rotor resistance for an AC motor or armature resistance for DC, would often have more than two intermediate steps, so it seems more likely to have been an autotransformer starter and you were changing voltage taps. But there were certainly some resistance starters with just a couple of steps so anything is possible.

Another possibility is that it was a synchronous motor, which was a popular choice for larger drives to keep the power factor up (and even compensate for low power factor elsewhere, by running it over-excited). In that case, the steps might have been off, star, delta, synch, but something that sophisticated would probably have merited an ammeter.

I wish I could get one of these installations complete to rig up in the museum workshop. It's a way off. I have a nice big DC motor with 8" belt pulley, something like 50hp at 110V although the plate is missing. I think it served in a wood shop, it was packed with sawdust to the point that the armature appeared to be wound with MDF. Unfortunately no suitable starter for it, although I might be getting a couple of cast iron starting pillars - the kind with drum controllers with handles on the side, and glass windows - so if we are very lucky one might have suitable resistances and coil voltages. It would run nicely off one of the mercury arcs or DC gensets.