Liebherr R 996 B - Manual (Page 2)

Each Liebherr diesel electric truck was tested to Mt Arthur Coal's
specifications for overall sound power and frequency targets;
stationary, loaded, driven up a ramp under full power and unloaded
and driven down a 10% ramp under retard. The overall Sound
Power achieved the target of 113 dB(A) and complied with limits
across all frequency ranges. Similarly, the operator noise exposure
was substantially less than the 75 dB(A) level stipulated by
Mt Arthur Coal.
Liebherr's successful delivery of these machines, achievement
in meeting Mt Arthur Coal's Noise Specification and more impor-
tantly the lowest cost per BCM, has resulted in further orders. Mt
Arthur Coal will have one of the largest fleets of Liebherr Mining
equipment with new orders for 10 x T 282's bringing the fleet to
20 plus other orders for a third R 996 backhoe and a R 994 B
face shovel.
Excavators
The R 996 Liebherr Litronic excavators were all fitted with sound
suppression packages. The packages were designed as a series
of suppression modules that work together to reduce the overall
sound power of each machine. The sound attenuating devices
include sound absorbing panels throughout the engine bay, under
the deck area and inside the counterweight. Substantial enclosures,
lined with further sound absorbing panels were placed around
the power packs and the hydraulic cooler house. Access to these
areas is maintained via modified catwalks and ladders.
Noise reduction from the engine fans was achieved by using
multiple hydrostatically controlled units instead of a single belt
driven fan. The engine fans were also electronically speed controlled
to provide cooling only when required, reducing sound emissions
further. Exhaust system sound emission reduction was achieved
using primary and secondary mufflers tuned to reduce engine
noise.
Haul Trucks
The T 282 diesel electric haul trucks were assembled at Mt Arthur
Coal with comprehensive sound suppression packages. The noise
reduction features include an aerodynamically designed fan
coupled with a larger capacity radiator ensuring ample cooling
capacity at lower fan speeds. Fan noise was further muted by a
specially baffled grille, while still maintaining a similar profile to
a conventional truck. Both the access stairway and the grille were
also engineered to allow easy maintenance access. To reduce
noise associated with retarding, a high volume, low noise radial
fan was installed which delivers the cooling air to stainless steel
quiet grids. This reduces both grid blower noise and the electrical
humming often associated with retard resistors.
The trucks engine area was enclosed by a variety of baffles and
enclosures, fire resistant blankets were also installed for their
acoustical properties and durability. Access to the engine area
was maintained through doors on each side of the engine bay
and from below through double opening belly pans. A reduction
in exhaust noise was achieved by utilising specially designed
mufflers. Non reflective chain mesh mud-flaps were also installed
to help the trucks meet the directional requirements of the noise
specification.
The BHP Billiton Mt Arthur Coal mining operation located in the
Hunter Valley, New South Wales, Australia, needed to increase
their production level to meet the requirements of their domestic
and international coal customers.
The location of the open-cut operation, close to residential areas
in the nearby town of Muswellbrook, required the company adhere
to stringent environmental noise limits.
As significant reductions were required at the noise sources to
comply with these limits, Mt Arthur Coal developed a Noise
Specification that prescribes the maximum noise limits that can
be emitted from mining equipment under a range of test conditions.
The ability of the machines to meet the requirements of this Noise
Specification was a critical factor in equipment selection.
The noise limits specified by the mine for excavators and trucks
was 116 dB(A) and 113 dB(A) respectively. Ongoing compliance
under a range of operating conditions in accordance with Australian
and International Standards remains the responsibility of the
equipment supplier.
Liebherr and Mt Arthur Coal worked together during the project
to achieve the required noise level reduction. The project team
utilised engineering expertise from the production engineering
departments of both Liebherr's truck factory in Newport News,
Virginia, USA and Liebherr's excavator factory in Colmar, France.
The noise team leveraged Liebherr's existing experience in the
design and manufacture of noise suppression packages for smaller
equipment to develop innovative packages for the larger machines.
Liebherr met the required standards for both excavators and
trucks without any negative lifetime operational or performance
effects. This has established a new benchmark for mining
equipment sound levels, with both machines being the quietest
in their respective equipment classes.
R 996 Litronic Mining Excavator
Operating weight incl. sound suppression kit ____________670 t
Engine __________________________2 Cummins Diesel K 1800E
Engine output per SAE J 1995 _____________3000 HP/2240 kW
@ 1800 RPM
Special requirement _______Comprehensive sound suppression
T 282 Diesel Electric Truck
Engine __________________________________Cummins QSK 60
Engine output per SAE J 1995 _____________2700 HP/2014 kW
@ 1800 RPM
Operating weight incl. sound suppression kit ____________566 t
Payload capacity ____________________________________327 t
Special requirement _______Comprehensive sound suppression
R 996 Litronic Mining Excavator
Backhoe Attachment
Backhoe bucket
Capacity _________________________________________33,0 m
3
Cutting width ____________________________________4700 mm
Max. digging force _________________________1500 kN/153,0 t
Max. breakout force ________________________1670 kN/170,2 t
Assignment Report
Situation
Attachments Technical Data
Solution
The noise emission target of 116 dB(A) for excavators was required
by Mt Arthur Coal in both the static (engine 1800 RPM) and
dynamic conditions (engine speed, swing ring and attachment
movement to simulate digging activity). Additional noise limits
also applied across the noise frequency range of 63Hz to 8KHz.
Liebherr achieved considerable better values at 113 dB(A) under
static and 115 dB(A) under dynamic conditions. The operator
noise exposure was substantially less again than Mount Arthur
Coal's preferred level of 75 dB(A).
The R 996 shovels efficiently load all haul trucks on site with the
T 282 Ultra Class trucks needing six passes to load.
Performance