Trade unions were a group of workers that joined together during the 2nd Industral Revolution to protest about the conditions that they had in the factories and claim for better salaries. Consequently, they protest together in strikes so they could have better wages and better working conditions in the factories.
These kind of actions became common during the 2nd Industral Revolution when men, women and children were exploited by working in mines or factories for a very long period of time per day. First of all, modern labor laws such as safety regulations, minimum wages and working hours didn't exist at the federal level, and many state and local protections were struck down by the Supreme Court. There had been little need for economic regulation in earlier times and little desire to see federal intervention over states' rights until after the Civil War. This hands-off approach to the economy is called laissez-faire capitaSources:
http://en.wikipedia.org/wiki/Trade_union
http://en.wikipedia.org/wiki/Strike_action
http://es.slideshare.net/nhowell/industrial-revolution-strikes-presentation
Workers in the factories destroyed the machines because they considered them responsible for their bad working conditions. Living and working together made the workers become aware of their situation and start organizing themselves to improve their working conditions.
In the second industrial revolution people made trade unions because they wanted good conditions to work, more pay and good treat. Before trade unions were invented people had to work for 18 hours, in harsh conditions and with a little pay. After the trade unions people got less hours of work, better wages and paid holidays.
http://es.slideshare.net/dslrogers/the-second-industrial-revolution