Usage of worm gear

[blokespot]

I am trying to design a linear actuation mechanism using a worm gear. The target object to be pushed will be fitted with a rack and is meshed to a worm. The worm is connected to a motor driving the whole mechanism.

I understand that the worm power transmission efficiency is very low and I expect it to be between 25 to 50%.

However, what do this efficiency mean in light of the 90 degree change in motion (the rotary motion of the motor and worm is 90 degrees to the motion of the linear rack)? If I base it on torque, what does that translate to on the linear rack? How do I know the amount of load i can place on the rack (related to the previous qn)?

Would appreciate it very much if someone could provide some guidance.

[PinkertonD]

Hi,

As you have noted a rack and pinion is not generous with efficiency. Could you at all incorporate a lead screw system instead? Better yet a ball-screw lead screw and efficiency goes up quickly.

Maybe give us a better idea (plus sketch) of what you are trying to achieve and we can give a better idea on what might work to achieve that goal.

If you are going to stick with the rack approach, then some load figures, distances and speeds will be more useful here. It is impossible to asses issues when we may be talking about moving 17-ounces or 300 tons.

[jboggs]

Can you explain why you have chosen not to use one of the MANY commercially available worm-driven jack devices? There are many companies that make them for a wide variety of applications. Plus - added bonus for you - They are already debugged and proven! No need to swim around in intimate design details.