LEGO 2838: Native American Family

Ungeared, it has a high rotation speed and low torque, so for most applications it requires an external gear reduction. Geared down and quite efficient, this is the motor of choice for most applications.

Lego 2838

Performances are almost as good, and its weight is much lower. The innermost shaft hole is geared up by a 23/17 factor. Slow rotation speed, minimizing the need of external gear train. Its high speed may be also useful in some applications.But it’s efficiency at light load is pretty low (large current at no-load). An ammeter measures current flowing through the motor, a voltmeter monitors tension across. The 5292 also exhibit very high no-load current, here again caused by internal friction. This explains also the break in its speed/voltage curve. All train motors show similar no-load characteristics, especially a relatively high current. No-load current depends little on voltage.

Lego Technic Testing A 28 Year Old Vintage 2838 Motor

The motor is made in 1990, so the interiors rusted and it makes loud screeching sounds. It was bought on eBay for less than 10 …

Stalled torque is established from the maximum weight that can be lifted by the machine described below . Note that 71427 and 43362 motors, equipped with a thermistor , should be protected against frying (not tested though !!!). The train motors also contain thermistor limitations. Electrical power is measured with voltmeter and ammeter. Mechanical power delivered by the motor is evaluated from the time used to lift the weight by some height (5 cylinder turns – the first two turns are not counted to eliminate initial acceleration). Cylinder is directly placed on motor axle shaft, except for 2838 motor where a 1/5 gear reduction was used. Additionnal friction introduced may have somewhat impacted 2838 efficiency, but anyway this gearing is necessary for most applications. Torque displayed for this motor corrects gear reduction. A light sensor in front of a black and white cylinder reads the number of turns done by the winch, and the time needed to lift the weight. Because rpm/torque curve is linear a motor provides maximum power when load slows it down to half of no-load speed. When large current flows through the motor, self heating rises thermistance temperature and resistance value, so the current is limited by voltage drop across thermistance. A similar protection is integrated in 47154 motors, as can be seen on this photograph. Once current limitation is established (for example with a dead short), power dissipation in the driver is very high, and it quickly enters thermal shutdown mode. This is also the load where rotating speed is half of no-load speed (this assumes ideal conditions such as low internal friction, but according to load curves showed above, this is exact enough to be useful). Here are the curves showing mechanical power versus load torque for various motor combinations. The fake batteries where assembled from the sawed ends of old alkaline batteries, maintained at the right spacing with rods of hot melting glue. Open them at your own risk and only if you know what you are doing!!!

Micromotor 2986 is at its best when space or weight is at a premium. Minimotor 71427 is probably the best performer of the pack overall. The new 43362 is roughly equivalent to 71427, with slightly degraded performances. But its light weight can be a boon for many uses. Clear case 47154 provides a higher mechanical power than 71427, but at the price of a somewhat lower efficiency. Because of that, it also turns slowly and efficiency is somewhat reduced.

lego image native american falego technic testing y 1

Lego Technic Vs Ar Drone Why Lego Can’T Fly

Just a simple thrust comparison with pure, non-modified LEGO. Of course, you can run the RC motors at higher voltage, but it’s not …

lego image native american falego technic testing y 2

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