Generating a back and forth movement of an axle

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    Axle Movement
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Discussion Overview

The discussion revolves around the design of a mechanism to achieve back-and-forth rotation of an axle using a motor that only rotates in one direction. Participants explore various mechanical solutions, including the use of cams, cranks, and eccentric mechanisms.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes a system involving two cogs and camshafts to create back-and-forth motion of the axle.
  • Another participant questions the initial description, seeking clarification on the axle's configuration and the nature of the desired movement.
  • A suggestion is made to use a crank linked to the motor to achieve a 90-degree rotation of the axle.
  • Further elaboration includes the idea of using a crank or eccentric on the motor shaft to drive a Pitman arm, which could engage a pinion gear to control the axle's rotation angle.
  • Participants discuss the analogy of pistons in an engine to describe the proposed mechanism for movement.
  • One participant suggests looking up existing mechanisms, such as washing machine transmissions, to find established solutions.

Areas of Agreement / Disagreement

There is no consensus on the best approach to achieve the desired back-and-forth motion, with multiple competing ideas and mechanisms being proposed and discussed.

Contextual Notes

Participants express uncertainty about the specifics of the axle's design and the exact nature of the required motion, indicating that assumptions about the mechanism's configuration may vary.

Lobotomy
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Goal: To have an axle rotate back and forth from one position to the other.

We have a motor rotating in one direction

How so solve this in a smart/simple way?

I'm thinking having
1. one cog on the motor axle, rotating the same way as the motor
2. a second cog connected to the above cog that would then rotate in the other direction.
3. having one "camshaft" each, roughly L-shaped part, connected to each cog. The cams will then rotate in different direction.
4. The axle that should rotate back and forth is roughly Z-shaped with an "offset" part that will be touched by the cams.
5. This will generate a movement back and forth when the cams, revolving in different direction touches the offset part of the axle.

See my extremely silly drawing attached =)

*will this work in principle?
*is there a better/simpler way to do it?

Would there for instance be a cleverly designed cam shape that can singlehandedly do the same job if just put on the motor axle?
 

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Lobotomy said:
Goal: To have an axle rotate back and forth from one position to the other.
I don't understand.
Does the axle have two wheels?
Are those wheels free to rotate on the axle, or are they driven?
What do you mean by "back and forth", aim in a different direction, or rotate the axle about it's axis, forwards and backwards?
Why ?
 
Baluncore said:
I don't understand.
Does the axle have two wheels?
Are those wheels free to rotate on the axle, or are they driven?
What do you mean by "back and forth", aim in a different direction, or rotate the axle about it's axis, forwards and backwards?
Why ?

No it has nothing to do with wheels. There's no purpose.
The axle rotates like 90 degrees in one direction, and then it should rotate 90 degrees back to where it began. Thats the "requirement".

Problem is that the motor only rotates in one direction, otherwise you could just drive the engine in one direction and then put it in reverse and drive it back. Therefore you need some kind of mechanism in betweeen
 
If you only want 90° then a crank on the motor, linked to a longer crank on the shaft will do that.

If you want more than 90°, maybe several turns, then mount a crank or an eccentric on the motor shaft, that pushes and pulls a Pitman arm.
A gear rack on the Pitman arm, is engaged to a pinion gear on the rotating shaft.
The throw of the motor crank, and the size of the pinion, sets the angle of shaft rotation.
 
Baluncore said:
If you only want 90° then a crank on the motor, linked to a longer crank on the shaft will do that.

OK, I am not really following, do you have an illustration, video or so on something similar in principle?
 
Baluncore said:

ok so somewhat like pistons in an engine: first "piston" goes up, and the other piston down, and pushes the axle one way. Then the second piston goes up and the first down, pushing it the other way?
The axle would have like a U-shaped horsewhoe at the end.
 
Lobotomy said:
The axle would have like a U-shaped horsewhoe at the end.
Not necessarily. The motor could have a simple crank, or an eccentric.
https://en.wikipedia.org/wiki/Eccentric_(mechanism)

Since shaft rotation is not beyond about 120°, the connecting link does not need to cut the shaft axis. A radius arm clamped to the straight shaft, would be driven by one end of the link.
 
Just Google washing machine transmission. No need to reinvent the wheel.
 
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