The main LEGO train systems are all roughly compatible. They all use a 6 stud gauge, so with a bit of fiddling, you can use all of the systems together. If you want to be most compatible with the current track offerings, you're better off with 9V and RC/PF track. This question discusses the specific compatibility issues in more detail.
There are several ...
I'd like to add my all-time favorite LEGO piece:
x870cc02, THE BLACK WHISTLE!
The white brick is a microphone. Attach it to your train's motor and BLOW THAT WHISTLE! Depending on how short (or LONG!) your whistling was, the train would go forwards or backwards.
Real-world use: Not only did it drive your train round the bend, but your ...
The Mario element has six switches on the front:
The inside of the pants in the power-up sets include six plastic ridges that can be either high or low. They interact with the switches on Mario's torso in much the same way as the cuts on a key interact with a particular lock. The torso reads the pattern on the buttons to determine the power-up state. Here's ...
Over the years the LEGO group has made a number of different springs, dampers and suspension components. The most widely known ones are the springs in the 731 series, such as the above mentioned 731c04 (Hard Spring) and its cousins 731c05 (Normal Spring) and 731c06 (Soft Spring), but there are other more specialized springs as well, such as 32181 (which ...
As it turns out, the answer is yes! Even though the wings are flat and can't generate much lift, I was able to get up to about 15ft of distance on a 10ft drop.
click to watch the video
Here's how I did it:
First, you're going to need 2 of the set, or at-least two copies of the sails and some common Technic pieces. This is because the sails in the set are two ...
I believe the main reason is so that the pieces are easy to identify in the instructions - as many LEGO sets don't have the Technic style "List of elements used in this step" it's always a fun game of "Spot the difference" to see what's changed:
If those pieces were all red, then the target audience (5+ on those sets for example) might find it very ...
Minifig accessory "shovel" can be used for dispensing minute amounts of a powder. Urban legend attributes such usage to drug dealers.
The fact that amazon lists digital pocket scale (0,1 g resolution, 100g max) and an airtight container as "frequently bought together" hints it's more than just a legend and LEGO shovels are indeed used in this way.
The holes in Lego Technic work very well as holes.
By which I mean, I have built very successful motor-driven cross slides for small machine tools using Technic pieces.
When paired with nominally 4.8mm metric ground rod (which tends to have a negative tolerance) the 4.8mm holes are a nice sliding fit. Imperial 3/16" rod at about 4.76mm also works, but is ...
These pieces are frequently used for decoration now, but they were originally used for sliding doors, particularly on train sets. Here's one of the first uses from set 7838 in 1983:
While they could be used in structures, these were frequently used for putting doors on the train cars themselves:
These parts can also be used to create tracks for other ...
I once published a paper in a peer reviewed scientific journal using data gathered using a remote translation stage constructed from Lego Technic.
I could only get ~ +-1mm accuracy out of it, where the proper stages were more like +- 0.1mm, but it was good enough for a proof of concept and the proper stages were on back order.
Of course many people would ...
With a few Power Functions elements and a pair of propellers, I was able to build a motorized boat similar to the alternate model.
1x: 8881 Power Functions Battery Box
2x: 8883 Power Functions M-Motor
1x: 8884 Power Functions IR Receiver
1x: 8885 Power Functions IR Remote Control
2x: 30332 Propeller 3 Blade 9 Diameter
See it in action!
click to watch the ...
Yes, "Cherries / Cherry Pair" has 3.18mm connection also known as "bar". This type of connection is in system and is compatible with large variety of elements, including two you have mentioned.
Couple of examples:
There are two variant of that, which look very similar:
Stud.IO lists them as:
Brick, Modified 2 x 4 - 1 x 4 with Recessed Studs and Thick Side Arches
Brick, Modified 2 x 4 - 1 x 4 with Recessed Studs and Thin Side Arches
These can be seen below, thick in red on the left, and thin in blue on the right in the top picture (not a valid colour):
It's difficult to tell exactly what part this fragment came from, but it looks like it is part of a broken Technic gear or pulley. It looks like it probably came from 3736:
Your fragment looks like it was probably once one half of the center axle hole of that part.
In terms of repair, I suppose you could try to glue this back together, but given that the ...
The Travis Brick is the 1×1 brick with studs on four sides.
The nickname arose amongst LEGO Space builders. It was nicknamed The Travis after talented Space builder Travis Kunce. He liked the part so much he had a tattoo of it.
The brick is especially useful in SNOT techniques as it has studs on all but the bottom surface.
Picture little blurry, but this is what I see... The builder attached the tiles to Part Number Forty-Seventy.
Part #4864a, the (black) window piece is really trans-black in color, but the way it's used here, with it being reversed and all, obstructs the proper identity of the white 1x1 bricks, causing some viewing tricks on the eyes...
For this experiment we're using the wheeled Duplo push and go motor block and red cabin from Set #10874.
The wheel width of the motor is the same width as a non motor base.
So, for this train to stay on the six stud track, the wheels need to sit either on the inside of the tracks or the outside of the tracks.
As the last picture shows, the wheels ...
The full-base 1x1 round bricks were produced from 1955 until 1963, during the period when LEGO pieces were made from cellulose acetate (CA) plastic, but were sold until about 1966. According to Gary Istok's Unofficial LEGO Sets/Parts Collector's Guide the solid-stud full-base 1x1 round brick was only ever made from CA plastic. After the supply of them ran ...
The web pieces made of flexible string are perfectly serviceable real-life webs, even if they are too small for most applications.
Of course the LEGO brand magnets are working real-life magnets as well.
Some sets have included large air bellows that could be compressed manually (i.e. hit) to supply a burst of air to launch a projectile or a racecar.
The specific part (870) is identified in the other answer, however it is part of an assembly with its own part number:
827 Vehicle, Tractor Chassis
870's page mentions it has extra parts that it is used with, and 827 is the complete assembly (steering wheel + mechanism).
This page ...
This is a Minitalia brick - Lego produced different bricks for a while in the seventies for Italy (per Gary Istok's latest information: because the original LEGO was deemed too expensive). Minitalia bricks have weaker plastic (which shows on the studs on your brick) and don't use the Tube system underneath the brick, but an older patent which has the X marks....
These are Lego parts.
The part on the left is a hose end (752). It is found on the ends of hoses like this:
The one on the right is 6221 (Peeron 424).
This part was most commonly found in older Technic sets as a spacer or crank handle:
According to the set designer for the Paranormal Intercept Bus set, Niek van Slagmaat, the released product contains 3 references in total, which he identified in a presentation at BrickFair Virginia 2019.
You can skip ahead to the 22:43 time to hear him talk about the sticker sheet and the references it makes, which are listed below.
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