Cobra Middlesbrough Limited in the UK has been operating
Liebherr wheeled loaders at its rock salt processing facilities in
North Road for a number of years and this highly specialized
materials handlers is fully equipped and protected for what is an
extremely corrosive working environment.  Proof of the success
of these machines is that Cobra has taken another Liebherr
loader on a three-year equipment supply and maintenance
contract.  A new generation L 5502plus2ZK-HL wheeled loader
joins an existing L 566, replacing an L 544 which has come to
the end of its long, productive and trouble-free working life.
Cobra Middlesbrough Limited handles and processes around
500,000 tonnes of rock salt a year under contract to Cleveland
Potash Limited and which arrives on site by rail from Boulby
Potash mine.  The main uses for this product are road treatment
during the icy winter months (in great demand in the UK at the
time of going to press!) and, in a finer screened form, for animal
feed salt.  The incoming bottom-dump rail wagons discharge the
rock salt into conveyors below ground, from where it is
conveyed to the main stockpiles and subsequent processing.
Cobra distributes nationwide, with some of the rock salt
destined for export to continental Europe and America.  The
crushed rock salt is stored in open storage and under cover and,
in another part of the same building, the fine screening and
stockpiling of the animal feed salt is also car-ried out prior to
selling on to specialist animal feed suppliers.
The Liebherr wheeled loading shovels carry out numerous
tasks, including stockpile management, loading trucks and
spreaders and conveyor hopper loading for feeding specialist dry
bulk tankers.  The winter time is undoubtedly the busiest period,
when large volumes of salt need to be handled and loaded onto
trucks and specialist vehicles for the vital task of ensuring that
roads are treated against icing.  The loaders work predominantly
outside but also undertake stockpile management and conveyor
hopper feeding inside the processing sheds.
The Liebherr L 5502plus2ZK-HL is a high-lift version with
Z-pattern bucket linkage and is an articulated, hydrostatically
driven wheeled loader in the 16-tonne class with a tipping load
of 11,650kg.  Power is supplied by a Liebherr-made engine which
develops 130kW and is fully compliant with Stage IIIA/Tier 3
emissions.  The standard general-purpose bucket has a capacity
of 3m3 and, combined with the HL arms, provides a superb load-
over-height of 4.3 metres — ideal for loading material into
bulkers and a combination that gives excellent productivity in a
simple and cost-effective package.
An important feature of the L 550 is a high level, isolated
coo-ling system which is equipped with an automatically
reversing fan to maintain radiator cleanliness and efficiency;
cyclonic engine air pre-cleaners are also included to combat the
dusty environment. The hydrostatic driveline system on the
loader contributes to considerable fuel consumption benefits,
which the customer particularly appreciates and, with limited slip
dif-ferential in both front and rear axles, produces good efficient
pushing power when stockpiling whilst, at the same time,
prolonging tyre life.  Automatic central lubrication is standard
and greatly contributes to reducing maintenance time; the
system on the machine has been specially adapted with stainless
steel fittings for this salt application.
The operator’s cab is air-conditioned, equipped with an
adjustable steering column, joystick control for the attachment,
air-sprung operator’s seat and tinted glass.  Convex mirrors are
also included and Liebherr’s own colour rear view camera system has been factory installed, with the monitor built-in to the instrument panel, offering full screen or split screen ima-ging as required for all-round visibility and optimum operational safety.
To overcome the corrosion problems encountered when handling salt, the L 550 was subjected to some very special treatment and adaptations, all of which were carried out at Liebherr’s wheeled loader factory in Bischofshofen, Austria which is extremely experienced in these kinds of specialist modifications.
The paint specifications are highly detailed and include pre-treatment of steel panels, with post assembly of the structural parts as sub-assemblies being degreased and primed with a special epoxy zinc phosphate, prior to finishing with special polyurethane paint.
When total assembly has been completed, all the relevant areas of the loader are polyurethane painted again and various cavities are treated with a preserving agent and, where necessary, sealed.  The cabin is primer coated using an electrophoretic process, with the surface finish of powder coating.  This is the same
process as used in car production and proves to
have highly effective anti-corrosion properties.
Rubber tabs are fitted to the pedals and stainless
steel is used for all pedal ‘mechanics’.  Protective
sprays and coverings are applied to all electronics.
All radiators and condensers for the air-
conditioning units are constructed from Teflon-
coated aluminium; the engine, pumps, hose systems
and engine compartment are all specially painted.
Cable looms are sealed, contacts are sprayed with
Dinitrol 77 B after as-sembly and, where
necessary, rubber caps are fitted or sealed with
special silicone as required.  VCI coverings are
applied to enclosed electronics, headlights and
controls.  Stainless steel is used for the bucket
positioning guide and screw connections; wheel
pins and shiny contact surfaces are rust-proofed
and sealed with Dinitrol 4010.