Liebherr A 314 Litronic Mobile Excavator

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Liebherr A 314, picture 1


Pneumatic functions:

  • Forward dozer blade
  • Rear outriggers
  • Boom
  • Adjustable boom
  • Stick
  • Bucket, switchable to auxiliary tool circuit
Electric functions:
  • All-wheel drive
  • Steering of the front axle
  • Swing drive
Additional functions:
  • Oscillating front axle
  • Working tool changer
  • Openable doors for drivers cab, upper structure access
    and storage compartment

Introduction - Lower Carriage - Upper Carriage - Excavator Boom - Digging Tools - Remote Control - In Action at LEGO Shows
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Liebherr A 314, picture 2

The Liebherr A 314 Litronic is my first model I have been commissioned to build. In 2005 I have been asked by The LEGO Company to participate with some of my models at the Suisse Toy fair. Reason for this invitation was that 2005 was the year, LEGO introduced many new construction themed sets - in the City as well as in the Technic product line. I have been known to LEGO Switzerland as a builder of construction equipment models before so I got this rare chance to display my creations at the Suisse Toy fair.
The first day of the show saw the final of a nationwide building competition taking place at the LEGO booth. Builders of the best entries in the various age categories were invited to the show to build a model out of a limited amount of parts during a limited timespan so that the winner could be chosen. As a source of inspiration, The LEGO Company had organised a real life Liebherr A 314 Litronic excavator as main exhibit and eye-catcher for the booth.
Therefore I have been asked to build a copy of this machine ouf of my bricks to be displayed among my other Liebherr models, already existing such as the T 282 mining truck and the LTR 1800 crawler crane. It was a challenging build because I was missing some important parts for the model and I only had a few weeks left. Finally I managed to finish the model in time. The show was a great success but by comparing my LEGO version to the real excavator, I found many details I had to improve after the show. I hadn't seen the real excavator before the Suisse Toy fair. All I had was the official data sheet and a 1:50 scale model of that machine I got from Liebherr.
Two components of the real excavator determined the scale of my model. First there were the hydraulic cylinders. By combining two standard LEGO Pneumatic cylinders at their bottoms I found a solution that resulted in an approximate scale of 1:13 and worked good for all parts of the real excavator boom, including the boom, boom adjusting, stick and bucket cylinders. 1:13 turned out to be the perfect scale for the second important feature as well - the wheels. By comparing the wheel size of the real excavator to the different sizes available from LEGO, I found the 24x43 size and equal sized air-filled wheels to be the perfect match.
So scale was set thus the construction of the model could start...

Liebherr A 314, picture 3Liebherr A 314, picture 4

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Lower Carriage

Liebherr A 314, picture 5

As mentioned above, I set the scale to 1:13. Therefore the width of the model resulted in 24 studs. Liebherr offers different wheel options for the excavator's lower carriage. Besides a set of double wheels, single balloon tires are available as well. I opted for the latter ones because two 24x43 wheels side by side would have been slightly twoo wide making it difficult to implement a working steering mechanism still offering enough space for the frame in between the wheels. Thus the balloon tires of the 8455 backhoe loader would be the choice. They offer the advantage that the rim is yellow, matching Liebherr's standard color scheme. To be better able to bear the weight of the finished model, I stuffed the tires each with a Black Cat tire which perfectly fits in the balloon tire and on the matching rim.
Both front and rear axle are permanently driven. Power source are two geared 9V motors which found room in the storage compartments on the left and the right side of the frame respectively. They deliver their power to a common driveshaft at whose both ends sits a worm gear each driving the 24 tooth gear on the differential case of the axle. The rear axle is mounted rigidly to the frame while the front axle is of the oscillating type to handle uneven terrain.
Furthermore the front axle is steered using another geared 9V motor which found room between the two axles under the frame. Steering movement is achieved by rack and pinion and is transferred to the wheels using ball joint rods.
The real A 314 can be equipped with various combinations of dozer and support blades and outriggers. The standard machine comes without any of these useful additions. Nevertheless I opted for the combination I thought would be the most commonly used on excavators in Switzerland. And I proved to be right when I first saw the real A 314 at the LEGO booth. It was equipped with a forward dozer blade and rear outriggers. And so is my model. Both add-ons are powered by two standard Pneumatic cylinders. While the blade uses two cylinders side by side, the outriggers each feature a single cylinder. The dozer blade is able to lift the front axle off the ground. The outriggers though can't do the same with the rear axle due to their limited stroke. Nevertheless they proved to be very useful, together with the blade which has a stabilizing function as well when digging at maximum reach. Because of the oscillating front axle, the model tends to lean towards the stretched out boom without the blade and the outriggers lowered.

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Upper Carriage

Liebherr A 314, picture 9

The excavator boom is the most important part of the upper structure. It is discussed in the section below.
Besides the boom, the most striking detail of the upper structure is the driver's cab. It is eight studs wide and features an openable door. The interior is fully detailed with driver's seat with integrated joysticks for the digging motions, a steering column with steering wheel and a storage compartment behind the seat. Pedals are there as well. Outside details include mirrors, windscreen wipers, orange warning beacon, radio antenna and a canister for windscreen washing fluid. Behind the driver's cab on the left side is an upper structure access door. It leads to the service points on the hydraulic tank and the steering valves.
The back of the upper carriage houses the engine on the real A 314 which is installed transverse. On my model it offers space for the two geared 9V motors which deliver their power to a common pinion which in turn is responsible for the swing motion. The pinion interacts with a standard Technic turntable which is mounted upside down and connects the upper to the lower carriage. The engine compartment features an air intake filter housing, air grilles for the engine and the cooler and the exhaust pipe. On the first version of the model there was a straight exhaust pipe. After the Suisse Toy fair I changed this detail to a more complex tubing including a particle filter because I had seen this feature on the real excavator. The grille for the cooler is made of grey Pneumatic hoses to achieve its slanted shape.
The right side of the upper carriage houses the fuel tank and a storage compartment. The latter one features an openable door. On the right front side is a second access possibility which leads to the boom pin and the fuel filler on top of the tank. Further details include the right hand rear view mirror and handrails.
On the rounded back side the umbilical enters the upper carriage. It consists of six times two Pneumatic hoses for the six respective functions and three 9V cables for drive, steering and swing motions. Two times two hoses and two cables pass the turntable to power the dozer blade and outrigger cylinders and the drive and steering motors respectively on the lower carriage. Two train weight bricks placed under the umbilical opening counterbalance the weight of the boom.

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Excavator Boom

Liebherr A 314, picture 14

Not only the lower carriage of a Liebherr A 314 can be configured with many options but also the excavator boom. There are monoblock boom options with and without the possibility to adjust it sidewards as well as adjustable booms with and without the sidewards adjustable option. My model features an adjustable boom without the sidewards option. It is the most common configuration with mobile excavators in Switzerland. The reason is that an adjustable boom makes the excavator more versatile. The boom can be adjusted for big digging depths as well as a high vertical reach. On the other hand the boom can be configured with a smaller reach which offers advantages when lifting heavy loads like they appear when sewer pipes are placed. Furthermore the adjustable boom allows for a compact configuration which allows the excavator to take part in the traffic using its own motive power. This is usually not possible with monoblock booms because they stick out too far from the lower carriage and thus hinder the driver's view. Finally in narrow construction sites the excavator can swing using less space when the adjustable boom points vertically upwards and the stick downwards.
The adjusting mechanism consists of a hinge in the boom and a single hydraulic cylinder to adjust the angle between the two boom sections. Two more hydraulic cylinders are used to lift the boom and attach to the upper carriage's frame and the first section of the adjustable boom. The stick as well as the bucket motion use another hydraulic cylinder each.
Because the standard LEGO Pneumatic cylinders are too short, each cylinder of the real machine is implemented on the model using two Pneumatic cylinders combined at their bottoms. This method results in a sufficient stroke but has the disadvantage that more Pneumatic hose and T-pieces are needed. Furthermore it looks not as realistic as it could, using only one cylinder. But it definitely looks much more realistic than replacing the Pneumatics by some sort of mechanical pistons.
The boom on my model starts at six studs wide and goes over to four studs at the hinge section. The second part of the boom as well as the stick have a width of three studs each. The lengths between the various bolts connecting the boom and stick sections are true to scale. The motion range though is somewhat smaller than on the real excavator because by combining two Pneumatic cylinders the stroke to length ratio gets smaller than it would be on a one-piece cylinder. Nevertheless the achievable digging depth and horizontal as well as vertical reach are good. The lifting power is not bad either - it is always fascinating to see how powerful the standard LEGO Pneumatic components are!

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Digging Tools

Liebherr A 314, picture 19

The versatility of an excavator like the Lieberr A 314 is only achieved offering the possibility to use various tools. Furthermore it is important to be able to quickly change between tools to speed up construction work. Thus my model is equipped with a tool changer. Although many excavator manufacturers offer their own range of tool changers, my model is not equipped with a standard Liebherr but with a competitor's product. Liebherr tool changers would be painted white. Machine operators usually chose the tool changer according to the tools already available from earlier excavators.
The toolchanger on my model - the red assembly at the end of the stick - is operated manually. It works like its real counterpart although the latter one would use hydraulics to operate the locking mechanism. The bucket or any other tool is hooked in two clips on one end while on the other end a set of two bolts, which are part of the tool changer, engage with two matching holes on the tool. By retracting the two bolts, the tool can be released.
The digging tools I built for my model include two buckets and a clamshell. There is an excavation bucket with five teeth and a trench bucket with straight digging lip. The excavation bucket has a somewhat bigger volume while the trench bucket is wider but lower. The clamshell consists of two individual halves each powered by a small Pneumatic cylinder.
There is no additional air supply on the boom for tools like the clamshell. This has two reasons. First I run out of Pneumatic hose to be able to install another circuit. The second reason is that the umbilical connecting the remote control and the model would have got even bigger hindering the swing motion of the upper carriage. Nevertheless it is possible to hook up the clamshell. Because it is a tool that dangles freely on the stick, the bucket motion is not used. Thus the Pneumatic circuit can be switched from the bucket to the clamshell using two Pneumatic valves at the top end of the stick. A set of two hoses goes from the valves to two pipe sections on the left and the right side of the stick respectively where the Pneumatic hoses of the tool can be attached.

Liebherr A 314, picture 20Liebherr A 314, picture 21
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Remote Control

Liebherr A 314, picture 24

The Liebherr A 314 is the model with the highest playing value I've built so far. It offers three electric and six Pneumatic functions as well as some manually operated ones. All of the functions of the first two categories can be operated from a common hand-held remote control. It consists of three main components, the power source, the Pneumatic compressor and the control levers.
The power source is a 9V train speed regulator that plugs to a wall socket. For field operations it is possible to hook up the cables that are connected to the Pneumatic compressor and the levers to a battery box. The train speed regulator though offers the advantage that the speed of the model's motions can be adjusted and that you will never run ouf of batteries.
The most important component of the remote control is the Pneumatic compressor. Six small Pneumatic pumps are arranged radially around a common hub that rotates on a crank. The crank is directly powered by two geared 9V motors. Each one has a 40 tooth gear attached to its shaft which acts as crank and is used to synchronize the motions of the two motors with the help of a common intermediate eight tooth pinion. The crank motions of the two 40 tooth gears are connected by a common bar which carries the hub for the six pumps. A power cut-off switch, consisting of a small Pneumatic cylinder acting against rubber bands and a pole reverser switch, prevents from building up too much pressure in the system when no excavator movement is operated. The performance of the compressor is very good compared to a V-type multi-cylinder compressor. Because every 60 degrees of rotation of the motors one cylinder reaches its point of maximum compression, the pressure output is very constant. While on a V-type compressor usually only every 180 degrees of rotation there are two or more pumps reaching maximum compression. Thus the air flow is increasing and decreasing constantly. As mentioned above, the excavating performance of the model is very good. It is for example easily possible to lift the front axle off the ground using the dozer blade or to lift a full bucket of sawdust at maximum horizontal reach.
The third main component of the remote control are the levers used to operate the model's various motions. There are two two-axis joysticks, three additional Pneumatic and two electric levers. The left two-axis joystick controls the stick motion by moving it forward and backwards and the swing motion by moving it sidewards respectively. The right joystick controls on a forward-backwards motion the boom while moving it sidewards controls the bucket. The additional three Pneumatic valves are for the adjustable boom, the dozer blade and the outriggers. A forward-backwards polarity switch controls the all-wheel drive motion while a second switch, oriented sidewards controls steering of the front axle. Both joysticks and the lever for the adjustable boom are configured according the controls on a real excavator. So knowing how to operate the LEGO model is a good training for operating the real machine.

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In Action at LEGO Shows

Liebherr A 314, picture 29

As mentioned in the introduction to this model, I originally built it for the Suisse Toy fair in 2005. Thus the first picture shows the A 314 standing next to my Liebherr T 282 in a display case. The next three pictures were taken during the same show. This time showing the model standing on the real A 314's front section of the lower carriage frame. By comparing these pictures to the later ones, it is obviously that I changed some details after the Suisse Toy where I had the opportunity to analyze the real machine in detail.
The remaining pictures show the model during the LEGO Company's 75 year celebration at their headquarters in Billund, Denmark. I had been invited, among other LEGO fans from several European countries to participate in this event with my model. Especially to show the excavator in full action, I built a pedestal to place the model on a higher level so that it could dig its way through a pile of sawdust. The pedestal consists of a piece of road for the excavator and border construction for a cardboard box full of bulk material, in this case sawdust, as mentioned before.
It was not only me operating the model but also some employees of the LEGO company. Among them two well-known men, Kjeld Kirk Kristiansen and Jørgen Vig Knudstorp, owner and CEO of The LEGO Company respectively. It was a special honor for me having my model accredited by LEGO officials. The second picture from Denmark shows Jørgen at the controls of the A 314.
Finally a video recorded at the same location shows the excavator in full action with me at the control levers. Enjoy!

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Liebherr A 314, picture 36Liebherr A 314 video

AVI video (21 MB)

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