Dynamic structural steel is used in large mining equipment subjected to various forces and loads. Bucket wheel excavators consist of a bucket wheel, conveyor, and boom structure. They use a planetary gearbox to transmit power from motors to the bucket wheel. Modifications were made to the input pinion design and welding process to address issues like misalignment and cracking that were causing gearbox failures. Non-destructive testing methods were also employed to inspect for flaws before the strengthened planet carrier was put back into service.

1. By:
S.ARUN KUMAR
allfreesharez.blogspot.com

2. Dynamic Structural steel is steel Construction Material, a profile, formed with a
specific Shape or Cross section and certain standards of Chemical Composition and
Mechanical Properties
Dynamic – Particle is in Motion
Various Forces and Loads acting on a
Single Structure is called Dynamic Steel
Structure

3. WHERE IT IS
USED
?

4. World Largest Mining Equipments Used for
Digging the OB ( Over Burden )
IT CONSISTS OF THREE TYPES
C-TYPE
NORMAL TYPE
COMPACT TYPE

6. Luffing system
with winch system
Bucket wheel
conveyor
Operators cabin
Bucket wheel
with drive
Maintenance
crane
Counterweight
boom
Center chute
Discharge
conveyor
Slew deck
Pylon
Structure

7. Bucket Capacity of 1400L
2 X 750KW Motor for Input Drive
Bucket Wheel Gear Box
Hoisting and Lowering Winch
Rotary Plate
Bucket Wheel Conveyor
Bucket Wheel Boom

8.  This BWE Gearbox Consists of
2 Inputs is Coupled with Two
750KW motors.
 It Consists Of Two Stage Planet
Carrier
 It is a Planetory Type Gearbox
 The Reduction Ratio is 182.398
Input RPM = 980
Output RPM = 5.37285

11.  The Input Pinion is Bevel Type Shaft
 It Consists of Spherical Roller Bearing
And Pair of Taper Roller Bearing
 It has one Housing made up of Steel
Grade ST52.3 ( High Tensile Steel
Material )
 The Pinion Projection Coupled With
Gearbox Top Shell with Roller Bearing

13. The Difference between the
two shafts is
 Some companies like MAN
uses the gerarbox pinion
without projection
 O&K using with Projection.
 But I prefer without
projection pinion.

15.  The Projection of Input Pinion is
coupled with the roller bearing.
 At the Time of Operation of BWE
the Bucket Wheel Boom will
vobblues due to High Depth of Cut.
 Sometimes the Roller Bearing will
be mis-aligned and worn out, This
leads to High Friction
 Sometimes the Welding Cracks may
Occur in the Shell, This will leads to
damage the Entire GearBox.

16. GEAR DATA
PINION WHEEL
No.of Teeth 16 39
Spiral Angle 14.28 14.28
Power 750 KW 750 KW
Input Speed 980 980
Length 1075 812
Weight 149 211

17. GEAR DATA
PINION WHEEL
No.of Teeth 16 39
Spiral Angle 14.28 14.28
Power 750 KW 750 KW
Input Speed 980 980
Length 1265 812
Weight 178 211

19.  Spherical roller thrust bearings are designed to
achieve a high thrust capacity with low friction
and continuous roller alignment.
 This bearing type is ideal for operating
conditions that experience heavy loads,
difficulty in establishing or maintaining
housing alignment, or shaft deflection.
 Internal self-alignment of bearing elements
during operation compensates for shaft
deflections and housing distortions caused by
shock or heavy loads

20. Roller Bearing
Thrust Bearing
Thrust Bearing
Key Fit

21. This is the modified input pinion used in
Bucket Wheel Gearbox.

23.  The BW GB is a Epicyclic
Gearbox.
 The BW GB Consists of Two
Stage Planet Carrier
 Planet Carrier plays a vital role in
BW GB because the 2nd Stage
Planet Carrier Output Flange is
coupled with the Bucket wheel
Input Flange
 The Planet Carrier Provides the
necessary torque to drive the
Bucket wheel

24.  This Planet Carrier Belongs to a
1400L capacity of BWE.
 This Planet Carrier is Made up St52.3
and 25CrMo4, These are High Tensile
Steel Materials, having tensile
strength of 510N/mm2 and Elongation
of 22%.
 If the BWE Operator Increases the
depth of Cutting Boom, More Torque
and Stress is acting on the Planet
Carrier, this results in cracks.

28. In order to avoid failures again, we want to
use the Proper welding electrode
The Electode was E8018.
Typical Mechanical Properties:
 Tensile Strength, psi 99,000
 Yield Strength, psi 87,000
 Elongation in 2”, (%) 25
 Reduction in Area, (%)
 70 Charpy V-notch (@-32F) 22 ft. lbs.

29.  It is a heat Treatment Process for
reducing the internal stress.
 This Process will more than 90%
of the internal stresses.
 In this case the Planet Carrier
stress is relieved at 210 ºC

30.  After Completing the all welding
Process, the Full Planet carrier is to
be tested by using NDT Techniques
 The Two Main NDT Process Used
here is
• UT ( Ultrasonic Testing )
• LPT ( Liquid Penetrant
Testing ).
 Liquid Penetrant Testing is to
detect surface cracks.
 The Ultrasonic Testing is used to
detect internal Flaws (or) Cracks.

35. THANK YOU