Is there a preferred solution to the problem of driving parallel rotary shafts from a single motor?

I have six shafts that I want to drive from one motor. The shafts are all:

  1. rotating the same direction
  2. parallel
  3. planar (although this is not a hard constraint)
  4. low speed and moderate torque (~100W/0.1HP)

If I were to wrap one timing belt on pulleys around each shaft, most of the shafts would have very low contact angles and would likely slip. Running six timing belts, one from each shaft to the motor, is ungainly and expensive. Gearboxes would be difficult to align, have low efficiency (40-80% from my research), and require frequent maintenance (lubrication).

This seems like it must be a solved problem, but none of the solutions I can find seem very elegant. Any suggestions?

  • $\begingroup$ Check out flat belts : lots of workshops did this sort of layout to drive many machines before electric motors became small and cheap (relatively). One drive belt drives a driveshaft and the others derive from that. $\endgroup$
    – Solar Mike
    Oct 27, 2017 at 6:07
  • $\begingroup$ There isn't one solution. There are numerous ways to accomplish this. It depends on what your design requires. Efficiency loss will always be a thing, so you have to adjust your design for your efficiency loss as well. You may find that 6 motors might be the best solution. What torque do you need? What output rpm do you need? What's your budget? What kind of load-static, dynamic, shock? $\endgroup$
    – GisMofx
    Oct 27, 2017 at 17:08
  • $\begingroup$ A diagram with dimensions would be helpful $\endgroup$ Oct 27, 2017 at 17:24

4 Answers 4


Consider a single large gear connected to the motor.

Smaller spur gears can be arranged around the central gear to drive as many shafts as the geometry allows. Each shaft will rotate in the same direction, but opposite to the central gear.

The ratio of the size of the central gear vs. the outer gears will determine the speed and relative torque of each driven shaft.

Designing the system to account for torque, inertia, shock loading etc is a much more complex problem.


Connect a belt from each shaft to the next. Space taken up is twice the width needed for a single pair connection. There may be a bit of slack introduced that way which can be reduced by doing a binary split so each shaft powers 2 others which will need up to $\log n$ belts on the first shaft.

Or you add a single smaller gear between each shaft that they couple onto.

You can also use tension wheels to push the single timing belt into the gears to increase contact pressure and area.


I was thinking about a chain kind of timing belts which any shaft has an input pulley and an output!pulley to the next shaft!!🙏😂


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