Sunday, 15 February 2015

Liebherr LR 634


Fully working 1:13 scale model of crawler loader

Real machine:



From Liebherr site:

 The crawler loader LR 634 Litronic features a comprehensive hydrostatic Liebherr travel drive. Constant power is provided to both tracks which are driven independently. The Litronic system for the LR 634 Litronic allows optimal control of the travel speed and all steering movements. Any required turning radius can be achieved with a simple hand movement, even turning on the spot. The robust Z-bar linkage with cast cross-pipe allows maximum bucket breakout forces and the low sill of the front windshield ensures optimum visibility of the working attachment.


Engine output
129 kW/175 HP
(ISO 9249)
Operating weight
20,746 - 22,694 kg
Bucket capacity
1.90 - 2.40 m³
Travel speed
0 - 10 km/h 



LEGO Model:


I choose big 1:13 scale as the rest of the last few models. That way they all can be present together. I have a plan to build few 1:13 sale truck, too.

Idea came as I love Liebherr machines, and this one looked quite nice to me. It is very curved in all directions, and it is mix between bulldozer and loader. It also has few optional attachments.


Chassis:


Chassis is built according to drawing of the real machine's chassis. It has main Dark Gray part and Yellow "nose". All the motors are in the gray part.
Chassis is built so it is symmetrical and has no weak points.
Chassis also incorporate 4 small turntables for connecting tracks and drive sprocket wheel to itself.
Those turntables prevent sprocket drive wheels and tracks to tore them self out of the chassis, while they allow infinite rotating.


Drive:


For the drive I used two XL Motors, geared 3:1, with thick double bevel gears, and the drive is virtually indestructible. The whole drive module is boxed in technic bricks, and braced with all sides to many points.


Tracks:


As I have somehow little experience with big tracked vehicles, I wanted to build this machine to be as strong as possible, in fact so strong that tracks and drive sprocket could not be removed without precise removing few key axles.
That is especially important to tracks, as they are not the usual tracks you find on excavators. Tracks on this loader are connected on two points to the chassis, but none of them is rigid connection.
First connection is at the back, where the tracks osculates around the axle.
Second connection is at the front, where the tracks are connected to each other and to the chassis via ball bearing equalizer bar.

For this, I used this setup:


Machines unique tracks attachment points creates lots of weaknesses on tracks, especially when there is more weight on the chassis.
To prevent this, I have added one more bar that connects tracks at the back, but also allows them to freely rotate. I am most proud on this solution. No matter how much weight is on the chassis, the tracks stays parallel to each other during driving.
Tracks and tracks insides are built with bricks and plates, and they are six studs wide. There is really very little empty space left inside them.
Also, to make driving more smooth, both front sprockets have tensioners.


Suspension:


Using arrangement described above, the machine has real pendular suspension, which allows it to drive over obstacle with one track, while other remains flat on the ground. On my model, I used the tightest ball bearing possible, and they work perfect. Tiny slack in the small turntables perfectly allow for the tracks to move slight laterally when one track in in extreme top or bottom position.


Loader arm:


Modeled to look accurate, not for strength. It can carry itself and the bucket and some load. Not made to be heavy duty.
Z-Bar kinematic allowed for fine tuning to achieve full range of big Linear Actuator movement.
I managed to achieve full range of bucket movement in any position, and good range of arm movement.
Also,  in this configuration, the bucket has vertical lift, which means that, while lowered or risen, bucket stays always in the same angle as it was in before the lowering/rising.
Normal loaders usually have radial lift, where bucket lose its original angle.

Loader arm is connected to the frame via 15L liftarm that runs whole height of the chassis and "nose" section, and it has 10 supporting points, making it impossible to bend or break.
Arm is powered by 2 M Motors, driven directly to LA's via 4 universal Joints in total.


Tool Boxes-Cabine platform:


The loader has two small tool boxes at the sides, and one big storage area beneath the cab.
It is very sturdy as it has to carry 1 kg cabine.
It has studs facing in 3 different directions, but still, not a single stud visible.


Cabine:


Cabine is most detailed part, and most noticeable.
It is white outside, and light blush gray on the inside. It has fully detailed interior, which is built according to the interior of the real machine. Also, it has tiles floor, with grill tiles to prevent slippage.
Most noticeable feature of the cab is "glass" which is built from really lot transparent light blue plates. It is curved to achieve organic flow with the cabine, ans I really like it. I have already built few of this glasses on my models, but this one turned the nicest. It seems that the fellow forum members does not share my enthusiasms, in a fact lots of them does not like it.



Cabine is very curved, only sections not curved are the sides. I tried to make the cabin as real as possible, and I ma very pleased with that. Well, after 6 rebuilts, Its gotta be.
I planned to make roof flat, but I remembered that I had some new white slopes in 1x10 lengths, and when I compared them to the blueprints, they matched perfectly! I incorporated front overhanging sections for front lights.
Details on the cab included handles, 3 per side, 


Engine tower:


At first I used slopes in various lengths, and it worked fine, but it bugged me that curve achieved by slopes is not very similar to the blueprint. Last two days of building I decided to destroy tower and make a new one with tiles. That way I could make it very close to the original, and also it allowed me to have more room inside.


Stickers:


I used stickers custom made to fit the model. I made them on my computer and printed them in a local printing firm on transparent sticky foil. There are around 18 stickers on a model. I think they really add a nice touch.


Attachments:


Main attachment for this machine is the Ripper. It is operated via two big Linear Actuators. In this version, they are operated manually. The ripper is not made to be able to cut earth, but to look and operate realistic.


Model performance:


Model performs beyond my expectations. It is very densely built and accordingly, very heavy, nearly 4 kilograms, and it is visible on tracks. They are extremely strong, but the problem is that they sag outwards, and away from each other, due to weight of the loader. After few days perfect solution came, and I installed that second self balance rod in a very elegant way that kept tracks perfectly straight and perfectly parallel to each other.

During filming the video, outside was still a snow, and I was afraid because all of the water. But i found great spot with both dry snow and clean tarmac to make the movie.

Model performed excellent, steered great, and pendular suspension really worked great due to heavy weight. Top speed is ok, it has a lot of power, and due to use of double bevel gears that were placed in line, and therefore their connection in the strongest possible, nothing never cracked. When the model face the obstacle, it either roll over it, or the tracks are spinning in place, or the motors stall.

This loader is one of my favorite mocs so far, and I intend to keep it built and to upgrade it to the new pneumatics when they arrive, and make them RC with LEGO servo motors.


VIDEO:



More photos: