still trying to think "universal" tire direction. and be ok-dokey. but really. agriculture tire treads, are designed for a certain direction.
and i am still not to keen on the "nasa spider rover" vs a regular caster wheel design setup. that has the 360 / rotational joint off set from center axle. the only thing holding me back. is the extra "rotational" space that a caster wheel structure setup would take up.
*keeps looking back at the nasa rover" man those extra linkages in the legs would be really nice and solve a lot of problems.
GAH, electrical motor instead of hydraulic cylinders. it is like, i can not even thinking electrical motors for joints.
BINGO!!!!. maybe, just maybe. ok, ya.... that might just work. some planetary gear sets most like a couple of them, to reduce say 3000RPM's with little torque, and convert it all to extremely low RPM's as in counting .1 to .00000001 of a degree of rotation. BAH. that might give me torque, but holding that torque and degree of rotation *grumbles* let alone the ratio conversion. ggggrrr. well DUH!! wet brake discs. errr acting like a clutch. that might work out nicely.
turn on motor, let it build up the torque, and then dis-engage the clutch errr brake, rotate to wanted degree, re-engage clutch errr brake, turn off motor. will already be running coolant lines and electrical lines right next or through the joint. errrr coolant lines through the joint will be needed. stinking explosion proof = fully enclosed motor. to reduce chance of any chance of a spark. = no way to cool motor. with exception of directly coolant. and a joint may be working itself non stop in a field.
seriously this might work. same brakes (take your pick of type of brakes) holds huge amount of force, with very little effort.
the problem, is the actual electrical motor in the joint. *ouch* enough, force, i guess torque, would need to be had. to fully lift, i guess at max, 1/2 to 3/4 the entire weight of the SSTT. ok maybe 1/4 the weight, if acting with another wheel and joint combo set.
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besides above. i think trying to fold a wheel up into the support arms, like that nasa spider rover, is asking way to much, nasa needed tight small package, to get it up into space. agricultral tractor, still needs tight space, but more importantly needs good traction. meaning wider width tires. making things most likely unfeasible to fold tires up inside the linkages / arms. on other hand, if going with eletrical motors in the joints, having linkages folding up inside of each other, might be a high possibility.
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regular electrical actuators, i just do not see them happening. just not enough thread contact. and then a chance of stripping all the threads....and all it would take is one thread, out of shape, take out the entire actuator.
to note it, eletrical actuator, looking like like a hydraulic cylinder, that has a threaded rod inside of it. and a motor spines a nut that causes threaded rod to extend/contract.
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ok weight about the "weight" in a regular SCUT / CUT / Utilty class size tractor. that has a FEL and/or backhoe. hydrualic cylinders places weight in certain spot on the tractor. if going with something like the nasa spider rover, that weight would be moved a huge amount of weight either in front (for fel) or in rear (for backhoe) destroying center of gravity, and needing a bunch more
ballast.
for the SSTT on other hand. how much effect would it have on weight distribution?
placing electrical motors directly in the rims of all the tires. would be like filling the tires with a fluid. but now i am not using a hyd cylinder, that extends the entire length of a linkage almost. and in that spreads the weight out across the linkage. but weight is directly in the "pin" for lack or better term were the joint pivots.
with hydraulic cylinder, the cylinder and rod itself provides structure, to physically withstand forces being placed on things. but now...
drawing a complete blank, not even a chance for a clue or an idea to brain storm on.