Workplace Hostility and Possible Infraction of Regulations.?

In my company we're dealing with heavy amount of backlog. We've lost about 12 employees in the last 5 months and about 15% of the workplace is in restricted duties or on leave due to work-related injuries. Now we have no new hires but our work has increased by over 50% and there's a pressure to get things moving quicker. The new operational manager uses fear and intimidation to pressure supervisors and now it's coming down to the regular workers. The other day one supervisor was bullying my co-worker in the corner accusing him of slowing down and he was just standing there watching him. My co-worker just kept saying "Why are you doing this, I'm doing my job. What is it that you want?" I intervened asking what's going on he kept saying the guy doesn't meet his expectations and we need to get thing moving within an allowed time. Well, my co-worker has been doing that so I ask what the problem was and he kept repeating himself. I asked the sup if he wants to talk to the HR and he said no and instead he called a manager on vacation asking him he's having problems with my shift and asked a permission to have us sent home. That didn't happen but afterwards the sup told my co-worker not to bring this up to anyone else in the management staff. The other managers seem unwilling to help just citing productivity issues. Now the sup is saying that he was offended that I raised my voice. And he did apologize to my co-worker. Should I go consult a lawyer about this? My co-worker looked scared and upset so I stepped in. Nobody did anything about it and I couldn't believe it. I want to go to the HR but I'm not sure if it will help. I appreciate any guidance. Thank You.