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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Instructions For LEGO 8868 Air Tech Claw Rig
Wheels and Tires This set uses six of the smaller size foam 20×30 tires and wheels. The pressure is split and fed to the inlets of four selector valves switches with two outputs each.
While tandem rear wheels would have been nice, there is no way they would have fit into the width of this model. Selection of the switches in either direction allows pressure to flow to either chamber of the actuators.
Steering The front wheels can be steered using an overhead “Hand of God” control. This can be seen clearly in the animation.
The claw can be lowered to grasp the rear bumper to help keep the crane stable when the truck is in transit. The outer angle of the claws is leo at 90 degrees. The compressor has plenty of pneumatic pressure to lift the boom, even at full extend. This allows them to be clipped to lfgo which makes certain that the hoses move with the boom and jib and do not become tangled. Differentials The dual rear axles are both “live” and legk a pair of differential gears which incorporate a built in 28 tooth ring gear which can legoo either as a bevel or a spur, similar to the 24 tooth crown gear.
Model by Eric Albrecht. Technic “triangles” are used as lugs to attach to the rod end of the actuator. The front of the crankshaft uses a 3 blade rotor as a fan.
A weighted 2×6 brick is located at the back of the crane to act as a counterweight so that the turntable is reasonably balanced. The differential ring gears are linked via an axle with 14 tooth bevel gears at either end. The angle of the first section with respect to the boom is about degrees and is locked by triangles and lift arms. While this allows them to rotate at the same rate, it could make one differential rotate backwards. Extra length is required when at the centered position.
Click the image to download the LDraw file of this model. The compressor cylinder itself looks like a small actuator but has a port only at the head end. The color coded computer image shows the way the dual pneumatic cylinders are cross connected. A vertical axle which connects to the 16 tooth gear drives a horizontal axle elgo passes through the holes in the upper turntable.
This way, pressure lebo one to extend and one to retract simultaneously.
I’m sure no one will have any trouble finding a place to route even more pneumatic hoses! Unlike the other actuators, this one has to work in 88688 tension and compression, and in fact the lower tension force is what is used to close the claw. This allows the claw to remain perpendicular to the ground no matter what the jib angle is.
The two cylinder banks have a standard V angle of 90 degrees. The second axle drives lgo pair of 16 tooth spur gears and then the steering rack via an 8 tooth pinion gear. But it seems to work fine. There are five pneumatic actuators which have ports at the head and rod ends to accept input from the switches.
Click for an animation of the loader slewing. A combination of an 8, 24, and another 8 tooth gear pass the torque up without changing the gear ratio or direction. Because the crank pins are each offset degrees, the forward and back cylinders are synchronized. The smaller arm allows a greater range of motion; in this case almost 90 degrees. A real hydraulic actuator has significantly less output force in tension than in compression due to the fact that the annular area of the rod end 886 the cylinder is less than the full bore area of the head end.
To solve this, the ring gear of the second differential is located on the opposite side. Pneumatic Boom The main boom ,ego be luffed via a single pneumatic cylinder working in compression. 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.
A belt then actually drives the crankshaft of the engine via a pair of pulleys which increase the rotation about 3 times.
Air Tech Claw Rig | Brickset: LEGO set guide and database
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. 88688 makes the engine turn fast. The actuator attaches almost half way along the length of the boom.
A single compressor is integrated into the body. Because all of the other pneumatic hoses have to pass through the center of the turntable along with the driving leho, the crane can only turn so far before the hoses snag. Click for an animation of the boom in motion.
There’s a 9V motor mounted ,ego the battery box which drives a large pulley through a belt. Why they never used this again is one of the great mysteries and tragedies of our time.
It is important to get the two actuators even and centered when rigging the system to make sure that it can rotate 90 degrees in either direction.
Engine The rear wheels are used to drive a V-6 engine.