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Mobilbaukran MK 88
Traglast (max.): 8.000 kg
Reichweite (max.): 45 m
Max. Traglast an der Spitze: 2.050 kg
Reprint:
MK 80 vs. MK 88:
Manual versus
Inhalt
ww w.kranmagazin.de
Das int e rna t ion a le F ach m aga z in
für Kra n - u n d H e bet e chn i k
Automatic
Das internationale Fachmagazin für Kran- und Hebetechnik
Auszug der 83. Ausgabe, 16. Jahrgang April/Mai 2012
KM Nr. 83 | 2012 Kranmagazin
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Page 2
In Aktion
MK 80 vs. MK 88:
Manual versus Automatic
With the MK 80 a hydraulic cylinder plays a key role in the erection process.
Result: The procedure takes longer, the undercarriage engine has to run during
setup.
Intermat 2000: With the MK 80, Liebherr presented the first MK product developed on an AT chassis. Nine years
later, also at the Paris trade fair, the company presented a completely newly developed successor – the MK 88. The
KM editorial team wanted to know what distinguishes the two 4-axle cranes.
“MK 80 vs. MK 88” – this
was the mission that brought
KRANMAGAZIN to KappelGrafenhausen in the state of
Baden-Württemberg in Germany, where MSG Krandienst
GmbH has a branch office.
“We obtained our first MK
about four years ago” explains
Björn Jatz from MSG. “We
The MK 80 only has a 30° jib
luffed jib position angle.
started out with an MK 63,
which we were able to hire
out very well right from the
outset. But we soon discovered that this crane was too
small for our requirements.”
Therefore, in May 2010
the company put its first
MK 88 into service, followed
by a second one in Novem-
ber 2011. In October 2010,
MSG Krandienst GmbH also
invested in a second-hand
MK 80. The crane, which was
manufactured in 2002, was
only intended to remain in
the MSG fleet temporarily
but, like the two new MK 88s,
it was extremely popular with
MSG’s customers, and so, the
company still hires it
out.
This gave KM
the opportunity to
see the two mobile
Text and Photos: Manuela Buschmeyer
construction cranes in operation and make a direct comparison. Support came from
MSG’s crane drivers Felix
Bildstein and Martin Hartmann. The latter has worked
as a crane driver with MSG
since January 2010 and is an
experienced MK 88 user. In
October 2011, Felix Bildstein
moved from the heavy transport section to mobile tower
cranes and initially began
operating the MK 80 before
changing over to the MK 88.
Kranmagazin KM Nr. 83 | 2012
Two convinced MK drivers:
Martin Hartmann (left) and
Felix Bildstein.
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In Aktion
Within the scope of a test
drive and with the assistance
of the two drivers KM wanted
to literally “experience” the
conceptual differences between the two AT undercarriages.
But before the test starts,
the different tyres on the
cranes catch our eye. While
the MK 88 has 14.00 R 25
tyres, the MK 80 has to make
do with 445/65 R 22.5. This
is quite a significant factor,
since due to the design, the
MK undercarriage – like all
AT construction cranes – is
very low.
As we all know, the challenge for mobile cranes is to
reconcile two opposing requirements. On the one hand,
naturally the crane should
have a large radius and must,
therefore, be equipped with a
suitably large jib. On the other hand, for road transport, in
other words, when it is collapsed, it must not exceed the
4-m width limit.
And although such a situation didn’t occur during the
90-minute test drive, during
which both operators drove
With the MK 88 the erection process
is done via cables.
the two cranes alternately
through the Rhine Valley and
the undulating foothills of
the Black Forest, both drivers pointed out that the low
design of the construction
cranes on an AT undercarriage required a certain touch
in case of depressions in the
road surface or when driving
into uneven building sites.
“With the MK 80 more than
the MK 88 because it has the
smaller tyres,” the two drivers
agreed.
During our test drive
the MK 88 was well
ahead of the MK 80
on hills.
We find another difference
when take a look in the undercarriage cab: MK 80 with
clutch pedal, MK 88 without.
While the MK 88 uses the
automatic 12-gear transmission ZF AS Tronic, the MK
80 is equipped with ZF Ecosplit transmission (16 forward
gears). Although gear selec-
KM Nr. 83 | 2012 Kranmagazin
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In Aktion
View from the personnel lifting cage.
tion is done conveniently
with the steering drop arm –
the driver must still engage
the clutch and change gears
manually.
It was especially the hill
climbs that brought to light
what the manufacturer has
always said about its AS
Tronic transmission: Namely,
that it changes gear so quickly
and accurately that even an
experienced driver can’t keep
up with it.
In any case, during our
test drive the MK 88 was well
ahead of the MK 80 on the
hills, which was only partly
due to the different engines.
“Actually, I don’t interfere
in the AS Tronic automatic
transmission,” says Martin
Hartmann, “it changes gear
so smoothly that this is generally not necessary”. Even
Felix Bildstein, who initially
drove the MK 80 during our
test drive, had a lot of praise
for the automatic transmission after changing over to
also helps relax the driver,
while the MK 80 only has a
single-stage engine brake. It
may sound paradoxical, but
true to the motto ‘the one
with the better brakes gets to
the bottom faster’, the MK 88
Thanks to its five electronic travel modes,
the MK 88 enables driving comfort at the press
of a button.
the MK 88: “Although I don’t
have any problems at all with
changing gears in the MK 80,
I must say that driving in the
MK 88 is, of course, much
more relaxing due to the AS
Tronic.”
The 5-stage Telma eddy
current brake in the MK 88
was also ahead when it came
to downhill driving.
“By the way, the MK 88 also has marvellous directional
stability,” adds Martin Hartmann. “Sometimes we also
have to drive long distances –
and, for example, the MK 88
is very pleasant to drive on
the motorway. You simply engage cruise control and arrive
at the job feeling relaxed.”
However, what both drivers had to get used to in their
“MK 88 career” was the active
rear axle steering that works
up to a speed of 30 km/h.
“You really have to consider
that when you’re driving. The
rear of the MK 88 does actually swing out more and you
have a 4-m overhang to the
last axle,” explains Felix Bildstein.
But for that, thanks to its
five electronic travel modes,
the MK 88 enables natural
driving comfort at the press
of a button. Apart from “Road
travel”, the other modes are
Kranmagazin KM Nr. 83 | 2012
Rope vs. rod: Rope wins.
Page 5
In Aktion
During driving and operation it‘s clear that the MK 88 is the more modern crane.
“Smallest turning radius”,
“Crawler gear”, “Reduced
swing-out” and “Independent
rear-axle steering”.
On the other hand, with
the MK 80 both front axles
are steered and the rear axle
is rigid during road travel.
All-wheel drive is possible
with building site operation
and crawler gear is achiev-
needed only for the outriggers and the superstructure
is then used for the erection
process, with the MK 80 because the central hydraulic
cylinder is required for the
erection process, the undercarriage engine has to run
for most of the time. This hydraulic cylinder and under-
carriage engine are also used
able with the MK 80. In other
words, the MK 80 offers a
high degree of mobility and
In general, more manual work is needed to erect
manoeuvrability, but not in
such a versatile or comfortable manner as its successor.
After the test drive both
cranes returned to MSG’s
yard, where both cranes were
to be erected. A start was
made with the MK 80, and
the design differences between this crane and its successor became obvious very
quickly.
To summarize: with the
MK 88, cables and winches
are used to erect the crane –
in other words the whole
process is carried out with
wire ropes – but with the
MK 80 much of the work is
done by a hydraulic cylinder
in combination with tie and
erection bars.
And while with the MK 88
the undercarriage engine is
when the MK 80 jib is to be
positioned at the 30° angle.
With the MK 88 the luffed jib
positions of 15°, 30° and 45°
are implemented by adjusting
the guying winch.
The MK 80 was ready for
operation in 24 minutes – including raising it on the outriggers. With the MK 88, the
entire process took 14 minutes and 40 seconds. However, you can probably reduce
this by the four to five minutes that was needed to explain some of the differences
to the KM editor.
For example, that fact that
if the MK 80 is to be used at
just half hook height, some
manual work is needed before
the start of the actual erection
process – such as rearranging
certain bolts – which is unnecessary with the MK 88.
Generally, the MK 80 needs
more manual work, since as
opposed to its successor it
does not have an automatic
boom slewing facility, for example. For the crane driver
that means once the tower/jib
the MK 80.
unit is erected: he has to pick
up a rod and slew the jib manually. In addition, with the
MK 80 the jib interlock must
be released manually.
Another differentiating
feature is that, as opposed to
the MK 88, with the MK 80
the hook is not stored in the
lattice mast jib but hangs
down outside and therefore
has to be released manually
for deployment and locked
for driving. And when the
cranes have been erected and
the MK 80 and MK 88 cabs
slide down on the towers, the
MK 88 cab automatically has
its full legroom. However,
the MK 80 driver has to release the locks outside the cab
manually before being able to
enjoy the full working space.
Although with the MK 88
the complete tower is extended before the jib heel section
is hoisted, assembly is faster
than with the MK 80, which
unfolds the jib while the tower is being extended.
“The clear advantage with
the MK 88 is that for the erection process it doesn’t need
the MK 80’s hydraulic cylinder which operates much
slower. The MK 88 also offers three different assembly
modes, so that we can erect it
in many different deployment
and space situations”.
As mentioned at the start,
the MK 88 also allows three
different jib luffed positions,
apart from 15° and 30° also
a 45° angle. The MK 80, on
the other hand, offers only a
30° luffed position. “We work
mainly with the 15° and 30°
luffed positions,” says Felix
Bildstein. “But we have had
jobs that would have not
been possible without the
45° luffed position. I remember we had a job on a church
that we could not have done
at all with the MK 80 because
we couldn’t have reached the
necessary hook height with
it,” adds Martin Hartmann.
KM Nr. 83 | 2012 Kranmagazin
Page 6
In Aktion
Another difference: With the MK 80 the hook block hangs outside the tower/
jib unit and must therefore be locked separately.
Although, based on both
drivers’ experience the 45°
luffed position is seldom
used, compared to the MK 80
of course the MK 88 opens up
further areas of application
due to its much greater maximum hook height of 59.1 m
as opposed to 48.1m on the
MK 80.
For the dispatchers this
considerable increase in hook
height is an additional strong
marketing argument. But the
benefits for the crane drivers are features such as MICROMOVE and horizontal
load travel at the luffed jib
position – features that both
cranes have. Nevertheless,
Martin Hartmann finds the
sensor technology and controls of the MK 88 slightly
more sensitive, but does admit that this could also be
due to age differences; after
all, MSG’s MK 80 is celebrating its tenth birthday.
Both drivers praise the MICROMOVE function that is
activated by pressing a button
on the control lever. With this
function, the lowering speed
is reduced to a minimum
In practice, this eases the
workload of the crane driver
and also increases workplace
safety. Without this function,
if the crane driver does not
brake the load soon enough it
can hit the respective surface
with a hard thud. This is one
„But we have had jobs that would have not been
possible without the 45° luffed position.“
without the hoist gear brake
engaging. “This function is
especially useful for lifting
heavy loads into their exact position, since when you
brake the load, there is always
a slight delay until the hook
comes to a complete stop,”
says Felix Bildstein, explaining the advantages of this feature.
of the reasons why this feature is used often in practice.
Both drivers see benefits
in the new radio controls that
are available for the MK 88.
Here, too, the generation difference is obvious, as the
modern radio controls have
a data feedback display showing all operating data in an
easy-to-read manner.
“Of course, it’s much easier
to work with the MK 88’s radio control system. If, for example, a lot of parts have to
be removed from the same
position on a truck, you have
the advantage that the exact
radius is shown on the display or you can see clearly
where the trolley has to be
positioned. The display even
shows you how far you have
to let out the cable to pick up
the load, if you don’t have a
perfect view of the truck bed.
You can’t do that with the
MK 80, work such as that
can only be done if you have
a direct view of the working
area.”
In terms of practical features, the main benefit for
Martin Hartmann is the air
conditioning system of the
MK 88. “Even in this weather it can get really hot in the
Liebherr MK 80
Undercarriage engine Liebherr D926 TI-E, 270 kW, 1.650 Nm LiebherrD936L A6, 300 kW, 1.872 Nm
Superstructure engine
Max. load capacity 8 t 8 t
Max. radius 42,0 m 45,0 m
Max. load capacity at max. radius 1,7 t 1,85 t/2,05 t with additional counterweights
Hook height of jib horizontal 19,6 m/28,0 m 17,9 m/30,2 m
Max. hook height at luffed jib position 48,1 m 59,1 m
Kranmagazin KM Nr. 83 | 2012
Diesel generator 57,0 kVA
or external power connection 63 A/400 V
Liebherr MK 88
Diesel generator 48,0 kVA
or external power connection 63 A/400 V
Page 7
Nice to see: While the MK 88 takes the bend
easily thanks to the active rear-axle steering,
the rear axles on the MK 80 are rigid.
Here, too, the generation difference is obvious,
as the modern radio controls have a data
feedback display.
In Aktion
MK 80 cab,” says the MSG
employee on this sunny
spring day at the end of
March. My air-conditioned
cab in the MK 88 is really an
enormous advantage.”
On the whole, the comparison test between the MK 80
and MK 88 showed that the
MK 88 is the more modern
and also more comfortable
crane of the two in all areas –
from the undercarriage power train, through the erection
process, to the crane deployment. Where manual work
was needed on the predecessor, with the MK 88 much
has been automated and im-
proved in terms of handling –
in short, a new MK generation.
Finally, Felix Bildstein has
a word of praise for the
Liebherr service. When he had
a problem with his crane during a job, the Liebherr service number was busy. But less
than 3 minutes later the crane
driver received a call back
on his mobile phone. And
thanks to the phone support,
the problem was also resolved
within a few minutes – that’s
service for you.
KM
Test drive in a convoy with a clear view from the cab.
KM Nr. 83 | 2012 Kranmagazin
Page 8
In Aktion
Experience the Progress.
MK mobile construction cranes from Liebherr,
for night-time operations with no problems at all.
Low noise and exhaust gas emissions thanks to electric drive units
Fully automatic one-man assembly
Integrated construction site lighting
KM-LBC 728-05.12.e
Liebherr-Werk Biberach GmbH
Postfach 1663
D-88396 Biberach an der Riß
Tel.: (0 73 51) 41- 2245
E-Mail: info.mk@liebherr.com
www.li ebhe r r.com
Kranmagazin KM Nr. 83 | 2012
The Group
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