LEGO 8868 PDF
Released in , set has the first and only motorized pneumatic find on any LEGO® model, and in fact this is the only set with a motorized compressor. Find great deals for LEGO Technic Air Tech Claw Rig (). Shop with confidence on eBay!. Shop LEGO Technic Air Tech Claw Rig. Free delivery and returns on eligible orders of £20 or more.
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This way, pressure causes one to extend and one to retract simultaneously. The two cylinder banks have a standard V angle of 90 degrees. It is important to get the two actuators even and centered when rigging the system to make sure that it can rotate 90 levo in either direction.
This allows the claw to remain perpendicular to the ground no matter what the jib angle is.
One or two of levo pneumatic air tanks which came out years later make great replacements for the fuel tanks and really bump the functionality up to the next level with a virtually limitless source of pneumatic power. This makes the engine turn fast.
The compressor cylinder itself looks like a small actuator but has a port only at the head end. Why they never used this again is one of the great mysteries and tragedies of our time. A vertical axle which connects to the 16 tooth gear drives a horizontal axle which passes through the holes in the upper turntable. When driven to retract, pego forces air out through the 88868. The actuators are designed to work in compression during their power stroke.
Unlike the other actuators, this one has to work in both tension and compression, and in fact the lower tension force is what is used to close the claw. Click for an animation of the compressor in motion. But it seems to work fine. Click for an animation of the differentials in motion. The compressor has plenty of pneumatic pressure to lift the boom, even at full extend.
Ldgo pair of rack gears are connected to the actuators and are used to turn a 16 tooth spur gear.
A big diesel truck like this would indeed lrgo have a large displacement 6 cylinder engine although probably inlineso this engine fits very well. Because the crank pins are each offset degrees, the forward and back cylinders are synchronized.
The angle of the first section with respect to the boom is about degrees and is locked by triangles and lift arms. Steering, V-6 engine, dual differentials, pneumatic compressor, slewing cab, luffing boom and jib, grasping claw. Click the image to download the LDraw file of this model. A look at this computer image and those in the above sections will demonstrate that the hose’s path to this actuator is pretty circuitous.
The smaller arm allows a greater range of motion; in this case almost 90 degrees. Because of the very small area, this actuator has a small output force and the grip of the claw is not very strong, but it does the job. The second section is movable and is lifted by a single pneumatic actuator driving another pair of triangles. Leog pair of pistons shares a common crank pin. Pneumatic Claw A grasping claw on the end of the jib is driven by one of the new miniature pneumatic actuators. 8868 of these hoses then pass aft through another beam and up through the center of the turntable for the loader.
LEGO Technic Air Tech Claw Rig (8868)
Torque from the differentials passes through a long drive shaft to a point under the front of the engine. This serves to make this model pretty heavy. The steering arms may seem small for a model of this size, especially since the weight of the model is cantilevered out the wheels via only a single hole as a support couple.
Model by Eric Albrecht. While tandem rear wheels would have been nice, there is no way they would have fit into the width of this model. Steering The front wheels can be steered using an overhead “Hand of God” control. The second axle drives a pair of 16 tooth spur gears and then the steering rack via an 8 tooth pinion gear. With a compressor, 4 switch valves, 4 large actuators, one small actuator, and four rigid tubes, there are a total of 23 flexible pneumatic hoses to route through this behemoth.
The engine is made from cylindrical engine elements. Head end pressure extends the piston, while rod end pressure retracts it. While this allows them to rotate at the same rate, it could make one differential rotate backwards. Flex system rigid sleeves are used as pneumatic tubes to span the sections between the pneumatic hoses.
There is an integral relief valve which prevents the pressure from building above a safe level, although the torque required to drive the compressor to relief pressure slows the motor considerably.
The outer angle of the claws is fixed at 90 degrees. Wheels and Tires This set uses six of the smaller size foam 20×30 tires and wheels.
The front of the crankshaft uses a 3 blade rotor as a fan. Pneumatic Slew By this time, there had been quite a few cranes which featured levo slewing turntable, but this is the first time it was controlled pneumatically and it only happened one more time many years later.
The color coded computer image shows the way the dual pneumatic cylinders are cross connected. When extending, it draws in air from the atmosphere.
The actuator attaches to the middle hinge point of the claw which allows it to drive both sides at once. The overhead control 88688 an axle connected to a pair of 14 tooth bevel gears.