Practicing the pump drill can help you feel how the arms and shoulders should work during the transition from the backswing to the downswing.
Start this drill by making a swing and pausing at the top of your backswing, then rock and pump your right shoulder downward a couple of times; without rotating it toward the target. You need to feel how your right elbow tucks closely to your right side. (Right-hand golfers) Simply dropping your club straight down with your arms is not correct. Your arms and the club should move in response to your right shoulder tilting downward towards the ground.
This is a simple drill to feel the correct arm and shoulder action of a good swing where there is no necessity to make complicated adjustments on the downswing. Once you are used to this feel, try hitting a few golf balls!
Always remember to “Practice with a Purpose” – Chip Inks, PGA