Rational persuasion is a strategy that I use on a regular basis at my job. My team members and I often try to present a logical argument to encourage the contractor to design a system or piece of equ

Rational persuasion is a strategy that I use on a regular basis at my job. My team members and I often try to present a logical argument to encourage the contractor to design a system or piece of equipment a certain way. For example, if a relocation would simplify the design for them, we attempt to appeal to their common sense and present the justification as a win-win. We also use inspirational appeal, raising questions to their values and the pride they take in their work. If a poor design is presented, we question if it is something they really want to put their name behind, or if they would consider a different approach. The effectiveness of these tactics is dependent on the situation and of course the strength of the argument, but they are often successful when executed well with plenty of justification. Legitimate authority strategy is used when there is a clear contractual requirement violation, winning these types of arguments is usually much easier. 

Reference

Quinn, R.E., Faerman, S.R., Thompson, M.P., McGrath, M., & Bright, D.S. (2015). Becoming a master manager: A competing values approach (6th ed.). Hoboken, NJ: John Wiley and Sons, Inc.