The dial is a motor thermal overload, the large contactors look like they are set up in a reversing arrangement as the outputs (bottom connections) are coupled.
Anything with an overload on it controls a motor load.
M1-M2 are reversers.
If you are retro-fitting for a new control and do not have existing prints, It is a question of wire tracing to find out what is what, sometimes in a case like this it is best to come up with your own schematic and start over.
The contactors usually have a power or size rating marked on them.
BTW, yellow for control is the wrong colour code, this indicates that the power for this circuit originates from another enclosure and may be live when the disconnect is off.
There is no real convention when numbering terminals, however the U,V,W, usually represents a motor feed.