A meeting leader should be able to guide the meeting to get the most out of each member, whether prone to mouthing off or clamming up. He or she will be able to take discussions that are getting too heated or too long off-line, so as to avoid derailing the rest of the event. Only You must be aware, however, that you can't be both a meeting leader and a contributor. As project manager you may find you're itching to pitch in on some technical fight, but that's not compatible with being referee. Controlled conflict works well for thorny technical issues, but it must be allowed to run on an equal footing.
Constructive debate is pointless if hierarchical authority is more important than technical merit.
The most junior engineer can provide an insight, and should be allowed to speak as much as the gnarly old guys. Make sure your decision-making process is defined by who is most competent to decide, not who wears the right color of hat. There are many ways to make things happen such as persuasion, leadership, teamwork. You can spot people with this approach immediately in meetings. The first kind are generally sad little people who don't do much harm beyond making the rest of the team do their work for them.