EE OPERATING BRODERSON 15 TON CRANE WITH 14 - 51 FOOT BOOM. OPERATOR RETRACTING OUTRIGGERS, RETRACTING BOOM AND RAISING BALL HOOK AT SAME TIME. BALL STRUCK STOP BLOCK BUT CONTINUED OVER BLOCK, BOUNCING OFF BOOM AND FALLING THROUGH GLASS TOP OF OPERATOR'S CAB STRIKING EE ON HEAD. EE WAS WEARING HARD HAT. STOP BLOCK SAFETY SWITCH CONFIRMED TO BE FUNCTIONAL ONE DAY PRIOR TO MISHAP.