I need a strong torque motor which move slow. However, I don't want to use gear train because gears will be damaged easily by the strong torque. Please give me some suggestion.

  • \$\begingroup\$ "strong" equates to how much force? \$\endgroup\$ – Kortuk Sep 11 '12 at 6:25
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    \$\begingroup\$ A gear train in your transmission moves your car, a gear train in a winch can lift tons. I'll reconsider the "gears will be damaged by the strong torque" :-) ... And there are worm drives... \$\endgroup\$ – Axeman Sep 11 '12 at 6:43
  • \$\begingroup\$ Gears would indeed be normal for this. In extreme applications there may be stronger alternate forms. Another thing to look at could be hydraulics, especially if your ultimate need is not rotary, though that is possible too. \$\endgroup\$ – Chris Stratton Aug 22 '16 at 14:21

The cheapest and most common thing you will find is a stepper motor. You can salvage a few of those from old printers and scanners. And if you use microstep control, you can make it very slow and accurate (below the fundamental step of the motor). The problem with steppter motors is that they consume lots of current regardless of speed.

In any case, there are gears that can take a lot of torque. The gearbox in your car does a good job, for instance.

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    \$\begingroup\$ Stepper motors generally don't have a great torque. Unfortunately microstepping generate a variable torque, and under load this can leads to big positioning error without a closed loop controller \$\endgroup\$ – Axeman Sep 11 '12 at 6:48
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    \$\begingroup\$ Ah, but they do have a large torque for low rpms, when compared to other types of electrical motors. If OP says he doesn't want to use any sort of gears, he's limiting his options. As for microstepping, sure, it has its downsides. But it doesn't change the fact that it does allow you to drive a stepper motor smoothly. \$\endgroup\$ – Jonny B Good Sep 11 '12 at 8:07
  • \$\begingroup\$ No other specs were mentioned, so I assume this is for a simple mobile robot project. Of course nobody would use a stepper motor when you need 10kW of power. But then again, if you need a professional application, you won't go around asking on a site like this. \$\endgroup\$ – Jonny B Good Sep 11 '12 at 8:13

Did you know about these motors :

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I think the industry name is direct drive motors or torque motors , these are AC or DC servo motors that are wound and designed for High torque and low speed . Their main purpose is replacing a geared motors ( higher efficiency , better inertia , faster response , zero backlash ) there main application is rotary tables in 5Axis CNC machines and anywhere slew drives where used previously.

Some manufacturers are :

  1. HIWIN
  2. motorpowerco
  3. kollmorgen

A gear reduction or pulley reduction would likely be your best option to get increased torque and reduced speed. However, this would restrict the working speed to the exact ratio between the input and output gears or pulleys. Therefore, the solution would be a variable pitch pulley that would provide a wide range of ratios to arrive at the desired speed. There are variable pitch pulley sets that use a belt or a metal belt. The metal belt would likely not be practical for a custom-made device, but there are currently variable ratio transmissions in some automobiles. Check out the transmission in a new Nissan

  • \$\begingroup\$ Most electric motors can have their speed electrically varied, and the electrical complexity of doing so tends to hold up better than the mechanical complexity of a variable belt drive. \$\endgroup\$ – Chris Stratton Aug 22 '16 at 14:23

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