THIS IS THE TEST SITE OF EUROBRICKS!
Search the Community
Showing results for tags 'Subtractor'.
Found 3 results
-
I have been experimenting with Sariel's Studless Transverse Subtractor from pages 291 and 292 of his book. It went together really easily, very straight forward design. I am using two (2) M motors like in his design. My observations: 1. When I turn on the motor connected to the differential connected to the 6 l axels (the normal output of the Subtractor) I can make the outputs go forward or reverse. 2. When I turn on the other motor the outputs are reverse of each other. 3. When I turn on both motors (both forward or both reverse) only one output is driven. 4. When I turn on both motors and select one forward and the other reverse, the other output is driven. I have changed the motors to account for one motor being stronger tha the other and I get the same results. I just want to make sure that this behavior is normal before I continue. If it is, great! I can use this, if not I want to correct it before I continue. Overall I really like it, it is a compact and useful design! Thanks, Andy D -
Hey everyone. I built a compact subtractor as I thought I would give it a go. Unfortunately I doesn't work very well, doing 1-3 turns before the current protection kicks in and stops. Any ideas why? Is it cos I used the L motor and not another XL? I wanted it to turn on the spot so I thought a faster motor would work, and it does, it just cuts out. This is taken with the BB and IR not in place. Cheers. -
I really like this set, and even it has IMO a great gearbox, one of the first things I was thinking of after completing the build, was how to make it RC. I guess most of the six functions are straight forward, but operation of the claw is obviously more tricky. I tried to figure out if it was possible to operate the claw by the hoist string. I realized that it is possible to transfer motion to a pulley in the claw simply by pulling the string on one side of the pulley, and letting out on the other side. The claw should then in theory be kept at the same level, and the motion transfered to the pulley could be used to drive the m-LA. To achieve this, I have used two reels, each of them connected to the ouputs of a subtractor (geared down 1:3 with Z12 and Z36 double bevel gears). If using tracked vehicle implementation of a subtractor as a reference, the "drive" part is done with a M motor driving a worm gear that in turn drives a Z8 spur gear. The "turn" part is done by a XL motor, directly driving the differential housings. I probably could use a L motor as well, thus avoid the coasting of the XL. The string I have used, is simple string for packing purposes. I guess it is better (and more puristic) to use the thick LEGO string, as it looks better, is more solid and no twisting. Problem is, can I get a thick LEGO string that is long enough? Please don't judge from the aesthetics, the main goal for me at this stage was to demonstrate the idea, and I have not put a lot of effort in the looks, or making it compact. Link to video: Here is my own judge for the idea: Pros: IMO it looks more clean than a hanging motor with it's supplying wires. Both hoisting and claw operation may be done simultaneously. Able to operate two functions with a simple string. Adding mechanical complexity to the model, something I like. Cons: The torque delivered to the m-LA is limited, so the grip of the claw is not very strong. It should be apx. equal amount of string on both reals, to achieve claw operation without changing the level of the claw. Claw operation is depending on friction between the string and the claw pulley. If the the claw is resting on the ground or the object it should lift, it will not work. Probably not real-life-like implementation of claw operation. Another idea I have, still not tested, is to convert the hoist string into a closed loop. the claw implementation is the same, with a pulley driving the m-LA. On the tip of the boom, there is a pulley, driven by cross axles from the super structure (the reason for location on the tip of the boom is to reduce length of the string, and number of pulleys, to reduce friction). The hoist may then be done by two pulleys pulled along the boom, towards the super structure. One of the advantages of this implementation, if it works, is that "Con #2" above is eliminated. I don't know if this description makes sense to you, I will try to test this version also. Main problem is, how to make a long, closed loop of LEGO string, without any bumps. I appreciate any feedback, including cons. And I also hope to inspire some of you to come up with a better solution. PS: Somebody who knows how to embed a "visual" youtube link, like most of the others do (I didn't figure out)?
