Meccano TAKRAF Level Luffing 35 Ton Electric Dockside Crane
Designed and built by Michael Adler
Cranes are an ever-popular subject for
Meccano builders and seem to demonstrate like no other models the many features
and advantages of the Meccano system. While
searching for a suitable subject, I came across this beautiful crane on a German
dockside and was immediately struck by its graceful yet powerful appearance.
Its all-welded construction gave it a clean, uncluttered look, free of
bracing and rivets, and one was struck by the very long flying jib and prominent
driver’s cab on the end of a long walkway giving an unprecedented view of the
Many examples of real beauty are found
in industrial objects, and here, surely, was one of them.
Perhaps this could be captured in Meccano, also using sound engineering
Prototype Takraf 35 ton level luffing crane
Research revealed that TAKRAF stands
for Tagerbergbau-Ausrustungen, Krane und Forderanlagen (Surface mining, Cranes
and Conveying Equipment). The
company, based in Leipsig, Germany,
is one of the world’s leading manufacturers of heavy surface mining and
transportation equipment. The company’s history goes back to 1725 when its
first factory was opened near Dresden; it started crane production in 1906.
After German unification, Takraf became part of the MAN company is now
The crane, which stands on the
dockside at Saarlouis in the Saarland, was manufactured in 1988 and has a load
capacity of 35 tons at 17 metres. It
is a double-luffing crane with two winch systems for a four-rope grab operation,
but it can handle a variety of other loads – it can be fitted with a hook for
general cargo, an electro-magnet for loading scrap and a spreader for lifting
The Meccano TAKRAF crane stands on
four floating bogeys, two of which have their own motors, and it picks up its
power from a dockside cable lying next to the track.
The cable is rolled onto a self-reeling wheel mounted on the gantry and
is paid out and taken in as the crane moves.
The roller bearing is the standard type with trapped balls; jib luffing
is by rack and pinion. The jib and
flying jib are fully counterbalanced by an overhead counterweight linked to the
jib. There are four falls of wire
from the end of the flying jib wound from four separate winch drums.
Meccano Takraf crane
A number of photographs of the crane
were found and from these a set of drawings were made with a scale of
approximately 1:12. Construction
began with the bogies and one of the braced side frames of the gantry. The
scale of the construction quickly became apparent; the final height of the
completed crane would be over seven feet. Large
models bring their own problems, with requirements for high strength and weight
loads. A very strong transverse
gantry beam was required which had to be entirely free from sagging.
This was achieved using a long box construction and very strong internal
bracing, further reinforced to prevent flexing from the column rising above its
middle. The gantry was then
completed, together with its two powered floating bogies, and run on tracks for
the first time. 6 volt
Faulhaber-type motors with 60:1 output were used and drive all the wheels via a
series of reduction gears. This type
of motor and reduction gear was used throughout the model.
Work then commenced on the machine
house chassis and the roller bearing.
The original construction incorporated a section inside the column with
the weight bearing at its lower end and a ring of side rollers above, but this
was changed to a more conventional system of trapped balls within doubled tracks
which proved more stable. Flexing
was encountered at the junction of the bearing and the chassis, which had to be
strengthened with a series of vertically-laid narrow strips sandwiched between
flat plates. The completed structure
was very strong indeed. The slewing
mechanism was completed, incorporating a 5.5” gear ring and 20 DP pinion.
The jib attachment at the front, the floor supports on each side and the
mountings for the superframe were then constructed and reinforced.
The superframe was then built and
attached, and the very large size of the model became quickly apparent.
Particular attention was paid to the upper end where a complex
construction was needed to support the jib counterweight, the flying jib tie bar
and the rope sheaves.
The luffing rack runs inside a
floating frame which adjusts to any rack angle; rollers grip it above and below.
Power from the motor comes through reduction gearing and a worm drive to
the final pinion; the mechanism is mounted half way up the superframe.
The jib is over 4 feet long and built
to withstand strong compressive forces while receiving support from the
counterweight. It is surmounted by
the long, distinctive flying jib controlled by a tie bar back to the top of the
superframe. The geometry of the
flying jib and superframe was calculated to provide true level luffing; with the
jib, flying jib and counterweight attached, almost full balance was achieved at
the outset and the luffing mechanism ran smoothly and strongly.
The winch system was designed to
operate a grab, as in the prototype, using two winches and four drums - two for
suspension and the others to operate the open/close mechanism.
There are a number of options in doing this, including using two
identical motors linked motors though a differential, or providing a means to
shorten the open/close cables relative to the hoisting cable by running them
through a roller system. The
differential system was chosen for this model and proved reliable and realistic
The winch house was completed in blue
plates to match the prototype; they contrast with the structure of the rest of
the crane built in zinc girders and strips.
The driver’s walkway was attached to the right side of the chassis in
front and required very rigid internal bracing to prevent it from sagging.
Radio, as a means to control the
crane, proved reliable and efficient, using five channels of a conventional
model aircraft-type duel joystick transmitter and extension.
Each motor was controlled by its own electronic power supply plugged into
the receiver, giving secure forward and reverse and speed control to each of the
motors. There was certainly
something fascinating about watching the grab close on a load and then release
it again, and seeing the crane slewing, luffing and travelling. This
is what the real crane driver must experience.
Drivers cab and the grab
If one lives at a distance from an
exhibition hall, it is a pretty formidable business to transport and erect the
whole large system and then expect it to function correctly and reliably. The
prototype Meccano TAKRAF was built in my study, and could not be moved out of
the room, let alone exhibited in another country.
The model would only ever be shown if it were built in England.
Richard Payn kindly agreed to build it, and he carefully followed my
documentation and photographs. He also suggested a number of features to improve
the model like strengthening the roller bearing attachment to the chassis and
redesigning the winch system. His
use of 1972 pristine dark blue girders and plates enhanced the crane’s
appearance immensely and I am deeply grateful for his collaboration in this
The Takraf crane with Michael and Richard at Skegness 2014
We will always be fascinated by
cranes, and the TAKRAF has been a wonderful Meccano project extending over
eighteen months, with many problems solved and challenges experienced and
Michael Adler 2016