Lipko Posted 3 hours ago Posted 3 hours ago Hi all! This is my entry for the contest, a fully pneumatic rock rat. Not strictly a monster truck, but rather a crawler. You can disqualify it if it deosn't fit the requirements. Sorry for the sloppy writing, I don't have too much time nowadays. Concept: To make an all terrain vehicle that would be operated/played with by mainly kids on exhibitions without the need of continuous supervision. This requires a sturdy model that's labor intensive to play with to encourage only brief play, so standard remote controller models woudln't fit. The next obvious solution is to have a pneumatic model with tethered control. The model is an exciting one for me, as it fulfils several personal goals at once: -to have a hand pump powered pneumatic engine for exhibitions -to build my first ever crawler -to have another vehicle to display on exhibitions (to have more models to rotate) -to ressurect my solid axle rat rod, but as a manual model. Or build something similar -Willy's jeep as rat rod was always my favorite rat rod type, but it's already done and done well (I couldn't find it at the moment) -my holy grail/nemesis: adjustable suspension The model will be a pneumatic engine driven, pneumatic steered, pneumatically suspended rock crawler based on Willy's jeep. It is not a high performance, high capable crawler. Simplicity is the main design principle as I don't have too much time for MOCing unfortunately. The design is planned to be a rat rod-ish, maybe a steampunk post-apolaciptic vehicle. My main inspiration is this: https://www.designboom.com/technology/jeep-rock-rat-haut-designs-01-26-2016/ Details The LPE engine has very low rpm but high torque, so the output will be geared up as much as can be done effectively. Four medium cylinders, one set in 90 degree phase in relation to the other set. This means an engine with no dead point and noo need for a flywheel. This is a common, obvious setup, I didn't invent anything about it. Since the motor only rotates in one direction, there is a forward/backward clutch, actuated pneumatically. It will be operated with the throtlle lever, and the engine will always operate then there is pressure in the system. The clutch will disengage the drive after a while if presure is not applied. This is to ensure that the model does't break when pushed. It is achived by simply leaking the two pipes that goes to the cylinder that's operating the clutch. Maybe I will put additional safety clutches to the half axles, I have to test that. Adjustable suspension, solids axles, four links. A very simple one, that uses only one circuit for the four wheels, so it only works when fully pressurized. Otherwise the chassis tilts and rolls. It will use long thin pneumatic cylinders. I estimated the load capacity, and should be strong enough to hold the model. I will apply limit straps, in order to protect the cyinders when the model is grabbed by hand. Four wheel steering, actuated by pnematics on both axles. The axles are mechanically coupled (gear-rack). Independent steering would be awesome, but it would be too complicated to solve proper centering (would require two cylinders per axle to make a three stage positioning, and much more complicated control). The hand pump are part of the controller device, but can be detached (so one person pumps, the other controls). Progress so far: -The engine prototype is done, and tested with a rolling chassis. Slow, but very strong even without proper bracing and optimisations. The weakest part is the drivetrain, the engine is so strong that it can twist an axle. Lubrication is not applied yet. -sketches of the whole model in Stud.io. Basic proportions, axle prototypes are made. https://f005.backblazeb2.com/file/Brickshelf/bs01/gallery/szecs/monster-rat/wip/WIP_01.jpg https://f005.backblazeb2.com/file/Brickshelf/bs01/gallery/szecs/monster-rat/wip/WIP_02.jpg https://f005.backblazeb2.com/file/Brickshelf/bs01/gallery/szecs/monster-rat/wip/WIP_03.jpg Quote
2GodBDGlory Posted 1 hour ago Posted 1 hour ago That plan sounds quite interesting! I look forward to seeing where this model goes Quote
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