Mercedes: What is that button on drivers side under the gas pedal?, transmission damage, mercedes benz

Question
My 1985 Mercedes Benz 190.D - 2.2 Engine.I need clairification on the drivers side floor right under the gas pedal. When Im flooring my gas pedal theres this button i hit and it powers up and the gear changes. Is this good to use this button? It does gear up more power. What Exactly is this button for?

Answer
The button kicks the transmission into second gear for passing. When to use the button is determined by how much power you need to get the vehicle up to speed to pass.
You want to be careful not to over rev the engine. There may be a clock out to keep it from engaging if the engine Revolutions Per Minute RPM are higher that a certain point to avoid engine or transmission damage.
good Luck
Robert