5. CALCULATING THE SIDE CLEARENCE
AND HEAD ROOM
r
R
A
D C
O B
DC
OB
AC
AB
DC
OB X AC
AB
6. SAFE USAGE OF CRANESAFE USAGE OF CRANE
VARIOUS LOAD TO BE CONSIDERED:
1. VERTICAL FORCES DUE TO LOAD /
WEIGHT OF CRANE
2. HORIZONTAL INERTIA
3. SLEWING FORCES
4. WIND FORCES
5. SIESMIC FORCES
7. STABILITY OF THESTABILITY OF THE
CRANECRANECRANE ACT AS A LEVER
C.W.
w
FULCRUM
THE FULCRUM IS NOT A POINT
CONTACT. AREA OF CRAWLERS
ACTS LIKE THIS
8. CRANE ACT AS A LEVER
STABILITY OF THESTABILITY OF THE
CRANECRANE
9. FOUR PARAMETERS ARE IMPORTANT
1. OPERATING RADIUS
2. HEIGHT
3. BOOM LENGTH
4. WEIGHT OF THE LIFT
13. SAFETY CONSIDERATIONS OF CRANES
STABILITY OF CRANE AGAINST TOPPLING:
STABILITY CONSIDERATION IS THE MAIN
CONCEPT CONTROLLING LOAD RATING IN A
CRANE. HENCE THE ELEMENTS WHICH
CONTRIBUTE TO ACT AGAINST STABILITY
SHOULD BE KNOWN :
IT IS GENERAL PRACTICE, THAT BASED ON
STABILITY THE CRANE RATING ARE SET AS A
PERCENTAGE OF TIPPING LOAD AND IN CASE OF
‘TATA CRANE’ ALL RATINGS INDICATE, 75% OF
TIPPING LOADS
14. SAFETY CONSIDERATIONS OF CRANES
THE TIPPING STAGE ONCE REACHED, THE CRANE
MAY START TILTING.
WHEN THE CRANE STARTS TILTING, OPERATOR
IS IN A VERY DIFFICULT POSITION TO CONTROL
THE PROBABLE ACCIDENT BECAUSE THE TILTING
MOVEMENT IS FAIRLY RAPID.
THIS FOLLOWS THE LOAD GETTING OUT OF
RADIUS, MORE AND MORE AND ULTIMATELY
LEADING TO THE ACCIDENT.
15. OPTIONS OF THE OPERATOR
1. TO DROP THE LOAD WHICH POSES SERIOUS
THREAT. THE OPERATOR SHOULD POSTPONE
THIS OPTION UNTIL IT APPEARS THAT OVER-
TURNING OF THE CRANE IS INEVITABLE
2. BOOMING IN (HOISTING THE BOOM) QUICKLY
CAN RECOVER STABILITY BUT THIS REQUIRES
VERY FAST ACTION FROM THE OPERATOR.
16. CRANE BOOM FAILURE
•BOOM SUSPENSION IS REQUIRED WHEN
LENGTH OF THE BOOM IS MORE THAN 70 FT.
•WITH MAXIMUM BOOM LENGTH AND GANTRY IN
FOLDING POSITION - CRANE SHOULD NOT
TRAVEL.
•WITH GANTRY LOW (FOLDING POSITION) NO
LOAD SHOULD BE LIFTED
17. FROZEN LOAD HANDLING
THE LOAD WHICH IS FROZEN ON THE GROUND
SHOULD BE LOOSENED UP BY OTHER MEANS
NOT BY USING CRANE POWER.
IN THE TOP MOST PART BUCKLING TENDENCY
IS OBSERVED
BOOM SHOULD NOT BE LOADED BY OTHER
LOAD OTHER THAN DESIGNATED LOAD
20. BOOM OVER CAB ACCIDENT
BOOM BACK STOP DOES NOT STOP BOOM
FROM GOING BACKWARDS, BUT IT HELPS TO :
1. PREVENT THE OPERATOR’S CABIN FROM
BEING DAMAGED - WORKING AS A WEDGE
2. WHILE TRAVELLING WITH LOAD ON UNEVEN
SURFACE IT PROVIDES CUSHIONING
21. BOOM OVER CAB ACCIDENT
REASONS:
1. IMPROPER ADJUSTMENT OF CLUTCH.
2. OPERATOR’S FAILURE TO DISENGAGE THE
CLUTCH.
OPERATOR CAN SEE THE BOOM BACK STOP
AND ASSESS THE CONDITION TO TAKE ACTION
24. PREVENTION OF “BOOM - OVER - CAB” ACCIDENT
1. MANY PEOPLE MISTAKENLY FEEL THAT BOOM BACKSTOP
PROVIDED ON A CRANE WILL PREVENT BOOM-OVER-CAB
OCCURRENCE.
THIS WOULD HAVE BEEN POSSIBLE ONLY IF THE BOOM IS PULLED
TOWARDS THE CAB WITH FAIRLY LOW LEVEL PULLS AND A DEVICE
PROVIDED IN THE BOOM HOIST CLUTCH, TO SLIP WHEN
ENCOUNTERED LOAD RESISTANCE, BEYOND CERTAIN SAFE
AMOUNT OF PULLS, WITH SIMULTANIOUS ALERT SIGNAL TO
OPERATOR FOR CORRECTIVE CONTROL ACTION.
HENCE ‘TATA’ CRANES ARE FURNUSHED WITH BOOM HOIST KICK-
OUT IN ADDITION TO BOOM BACK STOPS. THE BOOM HOIST CUT-OUT
STOPS THE LIFTING MOTION WHEN THE BOOM REACHES CERTAIN
PREDECIDED ANGLE. A FUNCTIONAL DEVICE OF THIS TYPE WOULD
PREVENT OVER LIFTING OCCURRENCE. THE CRANE OPERATOR
SHOULD ENSURE THAT THE BOOM HOIST KICK-OUT DEVICE IS IN
OPERATIVE CONDITION ON DAILY BASIS.
25. PREVENTION OF “BOOM - OVER - CAB” ACCIDENT
HOWEVER THE POSSIBILITY OF BOOM-OVER-CAB ACCIDENT
IS STILL NOT COMPLETELY RULED OUT AND REMAINING
FACTORS WHICH COULD CAUSE SUCH AN ACCIDENT IS
DEPENDENT ON OPERATOR’S JUDGEMENT. THE CONDITION
CAUSING SUCH AN ACCIDENT ARE AS UNDER:
1. DROPPING OF A HEAVY LOAD SUDDENLY OR ACCIDENTLY
WITH BOOM AT NEAR VERTICAL ANGLE OR SUDDEN FAILURE
OF HOIST ROPE.
2. WHEN TRAVELLING ON ROUGH TRAVEL PATHS CAUSING
EXCESSIVE BOUNCE
26. BOOM KICK OUT- FOR TATA CRANE
HOW IT FUNCTIONS:
WHEN THE HYDRAULIC KICK OUT SWITCH IS
DEPRESSED DUE TO BOOM OVER-HOISTING, THE
OIL UNDER PRESSURE FROM THE COMPENSATOR,
IS RETURNED BACK TO ZERO PRESSURE OF THE
RESERVOIR LINE, THEREBY DISENGAGING THE
BOOM HOIST CLUTCH.
27. THE PURPOSE OF BOOM BACKSTOPS IS THEREFORE
LIMITED TO FOLLOWING
1. TO GIVE VISUAL INDICATION TO CRANE
OPERATOR THAT HE IS REACHING UNSAFE ANGLE.
2. IN CASE OF BOOM-OVER-CAB ACCIDENT
OCCURING, THE DAMAGE TO MACHINE IS LIMITED
TO BENDING OF BOOM WHICH WOULD ARCH OVER
THE DECK MACHINERY, AVOIDING A DIRECT HIT ON
THE MACHINE.
3. TO ABSORB MINOR BOUNCING ON THE BOOM,
RAISED CLOSE TO MAXIMUM ANGLE WHEN THE
CRANE IS MOVING WITH LOAD.
28. SAFETY RULES FOR CRANE OPERATORS
1. NEVER PICK UP A LOAD BEYOND THE RATED
LOAD CAPACITY AT THE GIVEN ANGLE AND THE
LENGTH OF THE BOOM
2. NEVER MOVE THE LOAD OR THE CRANE
UNLESS CLEARED BY THE SIGNALER ON THE
JOB. THIS IS EXTREMELY IMPORTANT WHEN THE
LOAD IS HANDLED BY MORE THAN ONE CRANE.
3. WHEN THERE ARE SEVERAL PERSONS ON THE
JOB OBEY SIGNAL FROM ONLY THE PERSON
ASSIGNED AS THE SPOTTER (SIGNALLER). OBEY
ON EMERGENCY STOP SIGNAL GIVEN BY ANY
ONE.
29. 4. WHEN RAISING, LOWERING OR SLEWING
THE LOAD, PLEASE ENSURE THAT IT WOULD
SAFELY CLEAR ADJACENT STOCK PILES OR
MACHINERY.
5. NEVER LEAVE THE CRANE, WITH LOAD
SUSPENDED.
SAFETY RULES FOR CRANE OPERATORS
30. SAFETY RULES FOR THE HOOK ON HELPER
1. BEFORE BEGINNING EACH SHIFT, CHECK
SLINGS, CHAIN, HOOKS ETC.
2. WHEN CRANE IS TRAVELLING, WALK AHEAD
OF THE LOAD. NEVER PERMIT ANYBODY UNDER
THE LOAD.
