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Description
lego 40 tooth gear Technic Gear 40 Tooth | Part 3649Power Up Your Technic Builds Ready to elevate your mechanical creations? The LEGO Technic 40 tooth gear is a powerhouse part that delivers unmatched torque and control. As one of the largest standard spur gears in the Technic system, it's your go to solution for major gear slowdowns (also known as gear reduction), enabling powerful movements in your builds. Whether you're lifting heavy loads, powering a slow moving crane, or designing a custom
Power Up Your Technic Builds
Ready to elevate your mechanical creations? The LEGO® Technic 40-tooth gear is a powerhouse part that delivers unmatched torque and control. As one of the largest standard spur gears in the Technic system, it's your go-to solution for major gear slowdowns (also known as gear reduction), enabling powerful movements in your builds. Whether you're lifting heavy loads, powering a slow-moving crane, or designing a custom gearbox, this gear is a cornerstone of serious engineering.
Applications and Creative Uses
This gear is a builder's best friend for transferring power and motion with precision. Its large size makes it a perfect anchor point in complex gear trains and steering systems.
- High-Torque Gearboxes: Use it as the final gear in a reduction sequence to maximize turning power—ideal for vehicle lifts and heavy-duty winches.
- Turntables and Platforms: Its broad diameter is perfect for creating stable, slow-rotating platforms for cranes, excavators, or display builds.
- Precise Speed Control: Combine it with smaller gears to fine-tune motion and achieve specific gear ratios in functional models.
Start building your next mechanical marvel by combining this gear with other essential elements from our Technic gears collection, as well as Technic beams and pins and connectors.
Key Specifications
- Part ID: 3649 (Alternate ID: 34432)
- Tooth Count: 40
- Type: Spur Gear
- Compatibility: Fully compatible with all LEGO® Technic axles and gear systems.
A Little Piece of Trivia
The 40-tooth gear is more than just a part—it's a piece of LEGO® history. Introduced in 1977 with the original "Expert Builder" series (later renamed Technic), it appeared alongside the 8-tooth and 24-tooth gears. These foundational components made it possible to create real, functional movement in LEGO® models for the first time. Over four decades later, the 40-tooth gear remains a staple in Technic sets worldwide thanks to its unmatched versatility and performance.
Ready to take your build to the next level? Add this essential gear to your toolkit and unlock new possibilities in power, precision, and play.
LEGO® parts are intended for builders aged 4 and up. They may pose a choking hazard for children under 3 years old.
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Exchange/Return Notes
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4.2 ★★★★★
Based on 2034 reviews
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Product Reviews
★★★★★ 1
1 year review from a teleworker
Color: Grey
I purchased the Homall Office Chair in March of 2022, with high expectations of comfort and functionality. I liked how the chair looked, its price point, and it received positive reviews. Unfortunately, my experience with this chair has been underwhelming, to say the least. Several issues, ranging from poor quality to difficult assembly, have left me deeply dissatisfied with my purchase.
Let's start with the assembly process, which was an absolute nightmare. The instructions provided were not terrible, but not great either. It took me significantly longer than anticipated to assemble this chair, and I consider myself fairly handy. If you're not well-versed in putting together furniture, you may find yourself extremely frustrated.
Another significant issue I encountered was with the chair's hydraulic cylinder. It has already started failing, causing the chair to slowly sink, regardless of the adjustment settings. This rendered the height adjustment feature useless and made for an uncomfortable seating position. I expected a durable and reliable chair, but sadly, this was not the case.
The armrests were also a major disappointment. They started to deform and indent where my elbows and arms sit. The rest of the chair is fine. I can sit it in all day, so that is a positive. I mainly lean a bit forward and don't have time to lounge backward.
On top of all these issues, the Homall Office Chair proved to be quite noisy. Whenever I shifted my weight or made any slight movements, the chair emitted creaking and squeaking sounds. Not only was it an annoyance, but it also disrupted my concentration while working and is embarrassing on conference calls. Having such a distracting and low-quality chair in a professional environment is disappointing.
If I read this review I would have a couple of questions about the reviewer. I am 6'3" but well below the recommended weight. I review plans and specs as part of my job, so I am good with instructions. My hobby is woodworking which requires skill and a calm demeanor. Yes, I did retighten any connectors that became loose through normal wear and tear.
I should have spent more money on a quality chair since I am now looking to purchase a different chair 1 year later. I would advise others to take that into consideration. Spend a little more and keep less junk out of our landfills.
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Reviewed in the United States on May 26, 2023
★★★★★ 5
High Quality Rolling Chair
Color: Black/Silver
My son LOVES this desk chair. He has a drafting table to draw and do schoolwork on, and this provides him a comfortable chair to work in. It is sturdy and easy to clean. It does not fold, but it does roll easily. It was VERY EASY to put together. We were also pleased with the price. He will be able to use it for years to come.
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Reviewed in the United States on January 2, 2026
★★★★★ 5
The Greatest Chair I've Ever Sat In
Color: Black/Silver, Color: Black/Silver
When I was a boy, my first office chair that I used for PC and laptop work growing up was this chair. This was back before 2010 so it likely wasn't under the Amazon Basics brand but it was the exact same chair design. I've used that chair my entire life really and only had to buy this chair as a replacement as the leather started peeling significantly on my old chair after over 20 years of use. Even though the leather was heavily peeled, my old chair was still extremely comfortable and I would've kept on using it had I not gotten annoyed with having to pick up leather bits and pieces everyday from the peeling. I bought this chair as a replacement and the comfort is still as I remembered. No lower back pain, no butt numbness, no arm numbness, truly such a masterpiece of a chair where it lets you focus on the task at hand instead of focusing on the chair. Before I rebought this chair, I've bought & tried the Secretlab Titan Evo Nanogen, Furmax executive office chair, Neo executive office chair, RS high back gaming chair w/ flip-up armrests, Bestfair high-back office chair, FDW executive office chair, Herman Miller Aeron, and OFIKA executive office chair in search of a potential "upgrade" - every single one of these other chairs was inferior to the Amazon Basics high back office chair in one way or the other. The only thing I will note is that the pneumatic gas cylinder of the Amazon Basics office chair seems to be different from my original chair - it goes higher and has a higher minimum seat height. If you would like to perfectly replicate the original lower seat depth you will have to buy the S6124 extra short office chair gas lift cylinder from ChairPartsOnline - my only nitpick about such a phenomenal chair. In my attached picture I have the Amazon Basics chair w/ S6124 gas cylinder on the right next to the Furmax high-back office chair which although inferior is what I consider to be the 2nd best chair if for some reason you cannot get the Amazon Basics high-back office chair. To sum it up - I HIGHLY RECOMMEND THIS CHAIR!!!
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Reviewed in the United States on December 2, 2025
★★★★★ 4
Comfortable Office Chair
Color: Black/Silver
I have had several office chairs here in my office. Even though this office chair was a bit difficult to assemble, it appears to be a quality item. I was NOT impressed with the instructions - at all. More specific instructions would have been nice. Only time will tell if this was a good purchase and this chair is a good value. Not a bad price for the item as well.
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Reviewed in the United States on May 15, 2026
★★★★★ 5
All-around good chair, suitable for me at 6'6", comfortable and no issues
Pros:
The assembly is straightforward and doesn't require much strength; I would expect my mother to have no issue putting this chair together. If you're elderly or disabled, a relative or helper should have an easy and quick time of putting it together, and there is very little chance of making a mistake during assembly.
Sturdy at and slightly above the recommended weight limit. I peaked around 256 or 258lbs while using this chair, and it didn't show any signs of complaint then, and it hasn't shown signs of wear since.
Really comfortable. I'm an eight-hours-a-day user, almost without exception, and I have no complaints.
The leather holds up very well. I don't expect this to be true forever, but after approximately 1800 hours of use, there is no tear or warning sign.
It leans back super stably. That's the most important aspect for me.
It's tall enough to support my 6'6" frame. My back rests comfortably, so the odds are yours will fit, too. For the scary few who tower over me, and so you can search it easily, here's a height guide:
6'3" 6'4" 6'5" - The chair is good for your heights
6'7" - You should also be well served, unless your height is mostly in your torso.
6'8" - You're at the cusp. I think you will be comfortable in this chair, and alternatives that are built for our (mostly your) height cost so much more. I'd give it a try. I wish you luck.
6'9" 6'10" 6'11" - This is written for 6'9. For 6'10, 6'11, scale the significance of the caution. I think this chair will prove uncomfortable for you or encourage bad posture. I'd encourage you to look elsewhere.
Cons:
This is well covered in other reviews: the caps that cover up the screws on the side of the arms are poorly designed. One falls off every day or two. It's a minor inconvenience, but it's optional. You can toss the caps in the trash. The screws are not exposed. They sit deep within the plastic of the arm. Personally, I just push the covers back on when I notice they fell.
The armrests could be better for me, I think. I'm not sure exactly what my complaint is. I think they are a little too narrow for my liking, but I'm 6'6" with broad shoulders and long arms and unusual joints. The spacing seems fine for a typical user.
Notes:
I only sit leaning the chair back or sitting up straight at the edge of my seat. Some aspects of this review may not translate perfectly to locked-in-place, sitting back, upright usage.
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Reviewed in the United States on July 8, 2018
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