A very simple way has been just found working for me. See whether this works for you too.
1. Pass Equipment Number in 18 digit format like 000000000050001100 to the field OBJEK of table KSSK andget value of CLINT .
2. Pass this value (of CLINT above)to CLINT field of table KLAH and Get the value of CLASS which is your Equipment Class.
KJogeswaraRao