I want to convert rotational motion to linear motion. Since available space is limitation in my project, I was planning to use screw jack mechanism as a lift. But screw hack has very low efficiency - about 15% to 20% only. The rest of energy is lost to friction.

So I was thinking about using worm gear to convert rotational motion to linear motion of worm by not allowing the worm to rotate.

Is this possible and will it have better efficiencies as the contact area between worm gear and worm is much less than screw jack mechanism ? I can use any other gear mechanism also as long as efficiency is high....

Also I need a quick release mechanism to dis-engage the worm gear from the worm. Can some one please guide me on how to disengage the worm gear ?

Thanks Deval

  • $\begingroup$ Have you searched on here for similar questions? Something very similar was asked recently, I think... have a look at : engineering.stackexchange.com/q/25569/10902 $\endgroup$
    – Solar Mike
    Feb 27, 2019 at 14:16
  • $\begingroup$ Thanks for the reply. Worm gears are helical in nature so disengaging it is a challenge I see... In the mean time I have come across this video on YouTube which does the trick....youtu.be/MXFlmvrsrrE... All I need to do is to have the gear moved rather then the worm... $\endgroup$
    – devalvyas
    Feb 27, 2019 at 16:20
  • $\begingroup$ Check out ball screws. $\endgroup$
    – Eric S
    Jul 29, 2019 at 1:31

1 Answer 1


Rightly, the screw jack is not efficient for the job. For rotation to linear conversion usually Rack and Pinion arrangement is used. (Restricting the rotation of worm can also do the almost same thing.) The efficiency of rack and pinion is also high as the linear motion is raised because of normal forces at contact points unlike sliding in Screw jacks. The efficiency can go as high as 80-90%.

For the disengagement, you can instead disengage the pinion from it's shaft as is done in gearboxes. Attach a sleeve to the shaft and pinion for engaging and disengage and a synchronizing ring for smooth operation. For this, you will need to lose the shaft from its power source also. Consider a clutch plate in case of a continuous power supply. Refer to manual transmission mechanisms used in vehicles.

  • $\begingroup$ Why not a Scotch Yoke? $\endgroup$
    – Solar Mike
    Feb 28, 2019 at 10:59

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