Rotating and stationary shaft need to be engaged without slip

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Discussion Overview

The discussion revolves around designing a mechanism to engage a rotating flywheel shaft with a stationary shaft without slip, specifically focusing on the requirements for instantaneous torque transfer during a brief engagement period. The context includes considerations of mechanical design and potential devices suitable for this application.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests using a clutch for engagement, noting that clutches typically have some slip.
  • Another participant proposes a dog clutch, which interlocks two pieces to prevent slip, but raises concerns about its effectiveness at higher speeds.
  • A later reply questions the specifics of the RPM, energy transfer, and torque calculations, indicating a need for more precise requirements.
  • One participant mentions the Geneva mechanism as a potential solution, depending on the required rotation of the stationary shaft.
  • Another participant suggests a hydraulic system, describing a setup with a gear pump and hydraulic motor, including a mechanism to prevent early shaft movement.

Areas of Agreement / Disagreement

Participants express various suggestions for mechanisms, including clutches and hydraulic systems, but there is no consensus on the best solution. Concerns about the suitability of dog clutches at higher speeds and the need for precise specifications indicate ongoing debate.

Contextual Notes

Participants have not fully defined acceptable slip levels or provided detailed calculations regarding torque and energy transfer, which may affect the choice of mechanism.

Who May Find This Useful

Engineers and designers interested in mechanical coupling systems, particularly in applications requiring rapid engagement without slip, may find this discussion relevant.

koolraj09
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Hi guys,
So here's one thing which I want to design and this thing involves a flywheel rotating at about 1000 rpm. I need to transfer this energy to another shaft which is stationary with a mechanism. The mechanism has to be actuated for only a second, and then disengaged. During engagement, the two shafts - driver and driven shaft have to be coupled but without slip (positive engagement as we call it).

Is there any mechanism by which I can do this?
Thanks
 
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A clutch.
 
Use a Clutch. It is meant for this purpose.
 
Clutches do have a limited amount of slip and if the engagement period is short, that might be material.
The OP does not give any guidance as to how much slip is acceptable, but it may be that he needs something else. He needs to specify his requirements more precisely.
 
Hi again.
Sorry if the requirements seemed incomplete. But what I do need is a positive drive without slip. The torque (& power) has to be transferred to driven shaft almost instantaneously (order of milliseconds or less to get full torque).
Also the input is continuously rotating while the output has intermittent (single or half revolution) motion.
Is there a specific device which does this?
 
I think you are looking for a device called a dog clutch. This has two interlocking pieces, and when activated the two shafts are locked together so they can't slip.
 
What is the final RPM? How much energy is transferred and how fast? Have you calculated the torque that generates?
 
Thanks phyzguy and Russ...
Dog clutch is actually a good suggestion...but from what I know is that dog clutch operate at low speeds...
The speeds that I want to operate the mechanism is roughly 2000 rpm. The energy involved is around (roughly) 9500J. This is the flywheel energy and flywheel speed. This speed would be geared down, but the this energy has to be transferred in a fraction of seconds..say 0.5 or 1 sec to the mechanism.
Any more suggestion, guys?
 
Sounds like a Geneva mechanism might work depending on how much you need the stationary shaft to rotate.
 
  • #10
You could use hydraulics. A gear pump on the flywheel could circulate fluid through a hydraulic motor attached to the shaft. A shunt between the two hydraulic lines would idle the system. When the shunt is blocked by a sliding spool valve, (for one second), the pump will couple directly to the motor.

If early shaft movement is a problem then a sacrificial shear pin through the shaft would prevent any rotation prior to complete obstruction of the shunt.

The gear pump on the flywheel could also be used as a motor to spin up the flywheel by using a constant pressure hydraulic power pack.
 

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