The factories are an odd mix of old-style workhouses and newer, more efficient steam-powered production lines. Most of them employ the same cross-section of the population: a great deal of lower-class workers toiling in the noise and heat for a pittance. The newer factories also have a handful of skilled steamworkers, engineers and managers on hand to fix the machinery when it throws a cog across the room.
Since their founding the Rumblers have evolved to hold a similar structure to many criminal gangs; the only difference is that the people in command get /their/ instructions from the Arm. They have gained more and more autonomy since their crude beginnings as strikebreakers and gofers; the Rumblers now tend to be left to their own devices with a steady stream of funds from the Arm in the knowledge that if they do something wrong, it will dry up.
Power in the Rumblers isn't hereditary; they recruit people who they think are useful, and push upwards people who turn out to be competent. Their inner politics is not democratic as such: you advance when somebody high-up notices that you're doing a much better job than your superiors, and promotes you.
At the top there are a group of four men, nicknamed (in a move characteristic of the nonexistent sense of humour of the Rumblers) the Foremen. Each of these has his own chain of command, and the structure is not at all regimented: members don't have ranks or numbers or even authority over anybody but their own teams of goons. The Foremen tend to get on well and are generally middle-aged, paunchy, gruff, no-nonsense businesslike men who enjoy a pint of best and a read of the newspaper after work. In fact, that picture is fairly characteristic of the Rumblers at large: take the staff of a 1950s Welsh slate-mine, arm them with crowbars, pickaxes and various other easily-available factory implements, put them in charge of a major crime cartel and there you have them.
The main advantage the Rumblers have over the other gangs is cash. They're funded by an enormously wealthy group, perhaps the wealthiest in the city. While they can't just ask the Arm for money, they can certainly get hold of it in a hurry if there's a good reason. At the same time, the Rumblers don't go in for big, fancy, extravagant weapons - their blue-collar roots prevent it - but their members are well-paid and highly motivated, and the money still comes in handy for bribes if it's necessary.
They have two main weaknesses. Firstly, they're shortsighted. The Rumblers tend to concentrate on cementing their position in the Steam, rather than moving to take control of more of the city. What with the constant battle against the Steamworkers' Guild, this is understandable; most of their resources go into this feud, rather than expansion into things like smuggling, narcotics, prostitution and so forth.
Their second weakness is that they're at the beck and call of the Merchant's Arm, who are eager to ensure that their little militia don't get ideas above their station.
Steamworking is relatively new to the world of Horizon, and its Guild reflects this. While the Clockworkers' Guild is still mired in antiquity, the Steamworkers' functions much more like a trades union. Anybody working in a steam factory can buy membership, and the Guild agrees in return to support them and strive to help them attain certain rights; these are:
Of course, the Guild never actually manages to win these rights for all its workers-- it's still fighting firm opposition from factory owners (and in particular, from the Merchants' Arm) but it is making a genuine effort and most people are happy to stand behind them and fight for their rights.
The Steamworkers' Guild is obsessively democratic. Meetings are minuted in minute detail, votes are held for each and every position, and the system is moderately weighed down with bureaucracy. Not quite so heavily that nothing gets done, but the more bitchy members are quite capable of descending into endless squabbling over details.
One place where the Guild isn't so popular is in Irgar. The country has a strong tradition of vitality and the Irgarim take pride in their own ability to endure harsh circumstances-- like the belly of a hellish steam-powered factory. There is a lot of peer pressure for workers there to put up with the kind of dangers that the Guild promise to protect people from and stand on their own two feet without help from some lily-livered group of whiners; to be a member of the Steamworkers' Guild would be seen a sign of weakness.