Putting the ball in play:
The plate umpire pointing towards the pitcher with runners on base. The pitcher is on the rubber with the ball, and the batter is in the batter’s box. This allows the players and your fellow umpires to know exactly when a ball is back in play. This may or may not be accompanied by a verbal signal of "Play!"
No physical signal or gestures needed. Plate umpire gives a verbal signal of "Ball" loud enough to be heard by at least the batter and catcher.
No verbal signal is needed. Plate umpire gives his strike mechanic only. Commonly made by the right hand and arm.
Verbalize strike and show physical signal.
Dropped Third Strike:
Usually verbal and physical signaled strike optionally keep arm up to indicate that the play is not over.
Checked / Half Swing:
Point to the batter, then come up with your strike mechanic and state "Yes he did" or simply state "Ball, no he didn't go."
Checked / Half Swing with Appeal:
Step out from behind the plate, point to the appropriate partner with your left hand and ask loudly "Did he go"
If your partner indicates yes, then say, "Then that's a strike" and give the revised count. The base umpire should never respond unless asked by the plate umpire for a ruling.
Slide right hand down left arm and then come up with a strike mechanic. Some umpires slide their hand down 2 or 3 times then come up with the strike mechanic.
Both arms raised to shoulder level, palms facing out. Verbal mechanic is "Time". This should also be utilized when a batter has been hit by the pitch.
Same physical mechanic as "Time", Verbalization is "Foul" not "Foul Ball."
Lift your arms from your side or knees, fingers together and extended and lift them chest-high. Then come straight across to the sides of your body while stating "Safe."
Right fist together covered by the thumb, lift your arm crisply up above your head level and state "He's/she’s out." Out on the Tag: Same as Out, followed by a point to the tag and the statement "Out. On the tag."
There is never a verbalization for a fair ball.
No Pitch: Call
Verbalize "Time - No pitch"
Hands up around eye level with the appropriate number of fingers extended. Proper mechanic is to state "3 and 2" or "3 balls, 2 strikes"
The appropriate umpire points at the runner to be awarded and states "You - 2nd base", or You - score" while continuing his gesture toward the base being awarded. When multiple runners are to be given awards, the umpire should begin with the runner closest to home plate, and work back from there.
The signal is the right arm with index finger extended overhead in a circular motion.
Point to the pitcher and state "That's a balk." Allow the play to continue or call "Time" immediately, if appropriate. Place runners.
Point to the obstruction when it occurs and state "That's obstruction." Call time when the play has run its course and place the runners if needed and when appropriate.
Point to the interference, when it occurs and state "That's interference." Call time immediately or after the play and place the runners if needed when appropriate.
Catch / No Catch:
Out mechanic with verbal "That's a catch" or Safe mechanic with verbal "No catch - No catch."
Point into the air with your right arm fully extended. State either "Infield fly - batters out" or "Infield fly if fair - batter's out" if there is a fair-foul possibility.