SKU: 29578013213
gear linear

gear linear Technic Gear Rack 1x4 | Part 3743

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Description

gear linear Technic Gear Rack 1x4 | Part 3743From Rotation to Straight Line Motion The LEGO Technic 1x4 Gear Rack is a fundamental component that translates the spinning motion of a gear into precise, linear movement. This simple looking part is the key to unlocking a huge range of functions, from realistic vehicle steering to complex automated mechanisms. If you need a part of your creation to slide, extend, or steer, the gear rack is the essential link between your motor and the final action.

From Rotation to Straight-Line Motion

The LEGO® Technic 1x4 Gear Rack is a fundamental component that translates the spinning motion of a gear into precise, linear movement. This simple-looking part is the key to unlocking a huge range of functions, from realistic vehicle steering to complex automated mechanisms. If you need a part of your creation to slide, extend, or steer, the gear rack is the essential link between your motor and the final action.

Creative Applications & Uses

This versatile part is a cornerstone of mechanical design, enabling you to build sophisticated functions with ease. It's the go-to solution for any builder needing to create a **LEGO linear actuator**.

  • Rack and Pinion Steering: Combine it with a small pinion gear to create a classic **Technic steering rack**. As the gear turns, it pushes the rack left or right, steering the wheels of your car, truck, or rover with precision.
  • Sliding Mechanisms: Use gear racks to engineer smooth-sliding doors, retractable platforms, or extending arms for your MOCs.
  • Lifting and Actuating: Drive the rack with a worm gear or a standard spur gear to create powerful and stable lifting systems or custom actuators for industrial machinery.

Unlock its full potential by pairing it with parts from our Technic gears collection and integrating it into your builds with Technic beams and pins.

Key Specifications

  • Part ID: 3743
  • Dimensions: 1x4 Studs
  • Function: Converts rotational motion to linear motion.
  • Compatibility: Designed to be driven by any standard Technic spur gear or worm gear.

A Little Piece of Trivia

The 1x4 gear rack has been a staple of the Technic system since its introduction in the late 1970s. It first appeared in some of the earliest "Expert Builder" sets, most notably in the iconic 853 Car Chassis from 1977, where it was the centerpiece of the first-ever functional LEGO rack-and-pinion steering system. This innovation was revolutionary, and the part has remained a fundamental component for vehicle builders ever since.

Ready to add precise linear motion to your build? Get the Technic 1x4 Gear Rack and steer your creations in the right direction!

LEGO® parts are intended for builders aged 4 and up. They may pose a choking hazard for children under 3 years old.

Shipping Notes
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
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SKU: 29578013213

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J. Niederer
Whiting, US
★★★★★ 5
Impressive suit for the price
Size: X-Large, Color: Navy Blue
Order suit in my normal size (44R) and it fit perfectly. I’m 6’1” and the pant length set at the correct level. Quality fabric and stitching is well finished. Pants are comfortable at the waist with enough flex to be forgiving. Very good deal for the price…suit, vest and tie.
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Reviewed in the United States on May 22, 2026
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T. Hoffmann
Fort Morgan, US
★★★★★ 5
Great for tall, slender teenager!
Size: Small, Color: Light Grey, Size: Small, Color: Light Grey
Finding a suit for a tall, slender teenage boy is about as hard as climbing Mt. Everest. Until I found this one!! I was so pleasantly surprised that this suit fit my 15 year old son like a glove. He is 5'10'' and 140 lbs so he needs pants with the proper length and smaller waist. While the waist was slightly big, he didn't need a belt and the pants fell perfectly with a pair of Nike tennis shoes. I ordered a size small and would say the pants were a 32x32 but waist was probably more like a 31. Jacket and vest were a great fit as well. High quality and easy to steam to get the shipping wrinkles out.
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Reviewed in the United States on May 25, 2026
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IrishPuterGeek
New York, US
★★★★★ 4
Fantastic suite for the price!
Size: Large, Color: Khaki
I purchased the gray version to evaluate the suit. I ordered a size up based on other reviews and was pleased to discover everything fit well. The jacket fit well around the arms, chest, shoulders, and even my seemingly ever-growing gut. The vest was the same. The pants also fit well around the waist (thanks to the expanding waistband) butt, and thighs. The only problem was the pants were about 2 sizes too long. Considering the price point, I was felt I was still way ahead after paying to have them altered. After a couple week's worth of wear, I purchased 4 more (gray, black, blue and tan). All fit the same way and were easily altered too. The tailor even had the cashier ask me where I purchased these as he was impressed with the quality. A couple months in and I'm still pleased, although I've had a few issues. My right pocket on my blue pair has ripped it's seam twice, as has the same pocket on one of my gray pair. Considering it's the same pocket, I would suspect I am just heavy handed but this is not a common problem with any of my other clothes. The pants are a bit on the tighter side when I am sitting down so perhaps the stitching is just not strong enough. I have asked the tailor to give me a super stitch in this area and am just about to pick up the gray pair with this new stitch. I'll try to remember to update later on. Overall, I feel I have really gotten my money's worth out of these suits, especially considering the prices of others. I have been wearing these daily since June and have gotten many compliments.
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Reviewed in the United States on December 3, 2024
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CC Moon
Charlottesville, US
★★★★★ 5
Happy teen for prom. 6'1" 170 lbs medium perfect fit
Size: Medium, Color: Black, Size: Medium, Color: Black
This ended up being a great purchase. My son chose this suit for prom. He made sure to check the reviews and size chart and was very happy with the fit, quality and overall look. He's 6'1", 170 lbs and got a medium. It was perfect.
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Reviewed in the United States on May 10, 2026
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didibling
Lexington, US
★★★★★ 5
Great suit at a great value
Size: Large, Color: Black
I have ordered several other suits from the seller for my three boys over the last several years for either their prom, special events and graduations. The fit and value are wonderful. I would definitely recommend this suit if you want something that is classy looking, but won’t break the bank
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Reviewed in the United States on April 8, 2026

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