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Questions tagged [gears]

Gears transmit rotary motion and are commonly found in Technic sets.

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1answer
862 views

9398 the front wheels rotate in the opposite direction to the rear wheel

We've just finished 9398 4x4 Crawler. Everything looks good, the motors work but the front wheels rotate in the opposite direction to the rear wheels, they also turn in opposite directions. What could ...
5
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2answers
108 views

How can I assemble 2 opposing gears so that the axle rotations are perfectly parallel?

Due to the way all the modern LEGO gears are perfectly quarter-turn symmetrical, there doesn't appear to be any way to assembly 2 opposing gears such that I get a 2 perfectly parallel axles. This ...
11
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1answer
633 views

Part identification: 40t gear from The LEGO Movie

While watching clip of the LEGO Movie, I found a strange part: Slightly earlier in the video, its part number is shown as 3649. But it doesn't match the 40t gear I know nor the pictures on bricklink....
5
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1answer
100 views

Does LEGO Digital Designer include part 4539880?

Does anyone know if LEGO Digital Designer includes the part 4539880 (often used for housing differentials) ?
7
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2answers
194 views

9398 reduction change

I am studying implementation of 9398 crawler reduction. Here is the stripped part, in order to see the gears and their relation - the image is made with the excellent tool which is LDCad. My idea is ...
11
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1answer
162 views

High Torque Subtractors

I would like to use a subtractor in my next RC LEGO tank, as it enables the vehicle to turn on the move, as opposed to stopping and then turning. Unfortunately, the subtractors I have tested so far ...
10
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1answer
3k views

What are the dimensions of a technic axle?

I'm working on a LEGO compatible motor system that will be largely 3D printed. I want the connectors to fit standard LEGO axles, but I haven't been able to find the dimensions online, and I don't ...
4
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2answers
598 views

How to best transfer power at 90 degrees for high torque applications

So, I am building a tank model and this is the transmission I have been working on: Description: There are two gear pairs for gearing up (16t to 8t gears) and one gear pair for gearing down (worm ...
3
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1answer
146 views

Clutch gear test

I have two white 24t clutch gears, one marked as 2.5-5Ncm and another unmarked - how can I assembled them in a way to test which one "gives" first ) i.e. has torque before it slips - I was thinking to ...
5
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1answer
1k views

Any tips for aligning gears in LDD?

I'm trying to create the 42052 (Heavy Lift Helicopter), and other Technic sets. Aligning gears' teeth is relatively difficult, and the 'Hinge Align' tool rarely works. Please help!
1
vote
1answer
416 views

How can I build a compact EV3 gearbox?

I'm building a sumo bot in EV3 and would like to have both 1:1 and 1:3 gear ratios, with the first being useful for general driving and the second more for pushing other robots. My problem is, I ...
4
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1answer
140 views

Which system is more efficient?

I got a few XL power functions motors, and want to combine them to make a racing car. Let's get to right to the question: Which one save the most torque power? This one... ...or this one? PS: It ...
3
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3answers
371 views

How do I increase axle speed using gears

How do I increase speed of my output axle 24 times using 8, 16, 32, and 64 tooth gears using LEGO Mindstorms components? I checked Sariel's website but it was no help.
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2answers
2k views

Lego Digital Designer: Having Gears Interact with Toothed Bar

I just started using LDD, and I have been trying out a few things that I couldn't do with the limitations of my Lego collection. One thing that has me caught up is that I can't seem to get the ...
7
votes
2answers
375 views

Non-working technic system

Recently I've been working on a car which when going forward is fast, and when going backward automatically goes slowly. Here are two photos of it: (Just replace the text by "input") As you can see, ...
4
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1answer
294 views

Are DUPLO gears compatible with LEGO gears?

Can I make a transmission from DUPLO gear (Early Simple Machines Set 9656) to regular-sized gear?
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1answer
251 views

How to Motorize the LEGO Mars Rover

I am looking for some suggestions. My daughter is building the Mars Rover set (go here for the details: http://www.eurobricks.com/forum/index.php?showtopic=98222) for a presentation at school and I ...
4
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1answer
212 views

Any issues with this non-standard gear combination of 12t gears?

I don't see any "accepted" gear ratios for a stud-less direct-diagonal gear combination on sariel's excellent gear coupler but by shifting 12t gears such that they mesh off-center, it seems to work (...
5
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1answer
373 views

Which combination has a lower gear friction?

I need roughly a 1:3 reduction and I see a couple of ways to achieve it: using a 8t gear and a 24t gear (1:3) using 2x 12t gears and 2x 20t gears (1:2.779) using a 16t gear and a 40t gear (1:2.5) ...
7
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1answer
2k views

What is the “Module” of a LEGO gear?

Module, m this indicates the tooth size and is the number of mm of pitch circle diameter (p.c.d.) per tooth. For gears to mesh, their modules must be equal. Gear ISO standards and design methods ...
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2answers
3k views

How important is a center differential on a 4WD model?

I am looking to make a 4WD, single-engine powered vehicle, and I have seen others such as this which use three differentials to distribute the power to all 4 wheels: http://www.eurobricks.com/forum/...
2
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1answer
313 views

Can you use a beveled gear as a pinion?

I would like to use the PF servo motor for steering, however it is very large - I was playing with the idea of having it mounted vertically, and then using bevel gears to change the direction of the ...
6
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2answers
950 views

How much torque can a lego axle handle?

from to this question, it seems that the gears are stronger than the axles, which begs the question of how strong are the axles? if you connect one of the stronger motors, such as say the buggy motor: ...
6
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1answer
2k views

How to build a limited slip differential?

Lego provides a couple of ways for building a differential, such as this: and also provides a limited-slip gear like this: http://www.brickowl.com/catalog/lego-technic-differential-with-one-gear-28-...
3
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1answer
270 views

What does “No Friction” mean in Parts “Gear with 8 Teeth Wide, Notched and No Friction”

http://www.brickowl.com/catalog/lego-gear-with-8-teeth-wide-notched-and-no-friction-11955 As title, what does "No Friction" mean in the part "Gear with 8 Teeth Wide, Notched and No Friction" ?
2
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1answer
229 views

Parts/Step not fitting ( technic / gear not aligning)

working on Lego Technic; Recovery truck. Reached Step 27(book 1)....fixing the rope spool. and found that the white gear wheel is not fitting in. i.e., i have the white gear fixed on the shaft with ...
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2answers
515 views

Gearing down a PF XL

I'm looking for the best way to gear down a Power Function XL. I need to achieve a very slow output RPM (less than 1-2 RPM). I've tried a 625:1 gear (trough 40:8 gear). Can someone link to a well ...
8
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2answers
783 views

Any way to create a gear+chain, like for a bike?

I would like to create a LEGO bike. I can imagine how most of it would work, but i'm stuck at the chain. I need a way for the turning pedals (at one spot) to cause the wheel (in the back) to spin ...
12
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1answer
1k views

What's the purpose of the clutch gear in Power Functions set?

I have just bought this set and wonder the purpose of the white gear in the middle: How can you use it in your Lego Technic projects? Is it available in other sets?
13
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1answer
498 views

What is the difference between these hole shapes?

I purchased an assorted bag of LEGO Technic pieces. There are pieces with axle holes, but what puzzles me is that the holes are different from what I am familiar with. There's a piece with an ...
14
votes
1answer
2k views

How can I make a precise one-way clutch using Technic elements?

I need a mechanism so that if a (NXT) motor rotates forward, it moves one gear, but the other stays still, but if it rotates backwards, the first gear does not move, but the second one does. I found ...
4
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1answer
3k views

How can I controll the speed of motor using gears?

Can anyone tell me how to use gear wheels to modify the speed of the motor in the Power Functions set 8293? I know I could use the remote control unit, but I need to have a fixed slow speed on a ...
6
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1answer
981 views

Pre-Technic gears?

I have this set of LEGO gears. I remember seeing them first at my grandparents in the mid 80's. They predate my first Technic sets (~84 or 85). I have fond memories of my dad building a 3-speed ...
4
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2answers
823 views

What is the difference between 8T gears “Type 1” (3647) and “Type 2” (10928)?

On Bricklink I can see that there are two types of 8-toothed gear - a "Type 1" (3647) and a "Type 2" (10928). It's obvious these parts are not the same, but what is the functional difference between ...
11
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3answers
2k views

What are the torque limits of gears?

I am using Lego in the classroom to introduce students to geared machines. As part of this I am asking them to design a winch, using a small 1.5V DC motor and a collection of the common Lego gears, i....
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2answers
6k views

How can I transmit horizontal torque to vertical?

I have a setup where I have a step motor which I am attaching a gear onto. The motor will make the gear stand horizontal in a small vehicle. Is there any good gear combinations of LEGO gears that can ...
11
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4answers
7k views

How to make a conveyor belt with LEGO parts?

I am making a small robot with an Arduino and Technic LEGO powered by stepper motors. I am planning on moving small rocks throughout my machine. Does anyone have an idea of what kind of Technic LEGO ...
8
votes
1answer
1k views

Strongest gear configuration

I'm building a (what I hope to be) high-speed car using two PF-XL motors together and some gearing up. However, there's a point where I have to rotate the axle with power (that comes from the 3 speed ...
15
votes
4answers
438 views

How can I fix a flattened gear?

I have an old small gear that somehow got flattened to an oval shape. The axle hole is too narrow to slide a bar through, although it is not completely closed shut. How can I repair this gear?
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2answers
2k views

Are Samsonite gears compatible with modern Technic gears?

Do the old Samsonite gears (above) work with current Technic gears (below) LEGO bricks tend to be backward compatible with older bricks, but since I don't own any Samsonite gears I cannot tell. ...