Can I Convert a electric recliner chair to manual recliner?

[Chris Pennington]

Really? I don't know. I am going to go look at it. It looks like new, but I am sure it isn't. Would an electrician be able to do that?

[Andy Burns]

A decade later, it's probably rusted away ...

[Brian Gaff (Sofa]

Yes but its the control part you need and some makers may not want to sell you conversion kits, even if they were still a current model. Brian

[James]

Can I convert my electric recliner into a manual recliner

[Roger Mills]

A car jack wouldn't be much use if the weight of the car caused it to close again when you let go of the winder! Any geared/screwed device which is less than 50% efficient is non-reversible - including the motorised struts used on recliners.

[Dave Plowman (News]

I was wondering about that - but is efficient the correct term? More than the ratio of the worm and nut? (I'm guessing you could make a worm and nut which could reverse the power flow - if you wanted to.)

[Roger Mills]

ISTR that that was what I was taught in schoolboy physics about 65 years ago, but that may be an over-simplification.

It's certainly friction related, as described in this extract from Wiki:

"Unlike with ordinary gear trains, the direction of transmission (input shaft vs output shaft) is not reversible when using large reduction ratios. This is due to the greater friction involved between the worm and worm wheel, and is especially prevalent when a single-start (one spiral) worm is used. This can be an advantage when it is desired to eliminate any possibility of the output driving the input. If a multi-start worm (multiple spirals) is used, then the ratio reduces accordingly, and the braking effect of a worm and worm wheel may need to be discounted, as the wheel may be able to drive the worm.

Worm drive configurations in which the wheel cannot drive the worm are called self-locking. Whether a worm drive is self-locking depends on the lead angle, the pressure angle, and the coefficient of friction."

[Robin]

My recollection of O level physics in the same decade is that efficiency is precisely the right test. Other things such as the pitch of the screw affect the mechanical advantage. But self-locking in a simple screw jack requires the friction to be more than the load. It follows less than half the work done is useful.

[Roger Mills]

Yes, having given it some further thought, I believe that the 50% efficiency maxim is correct.

If instead of a worm drive, you consider using a rope to drag a heavy weight up a slope. If the friction force is exactly equal to the component of the weight along the slope, the weight will be in equilibrium and will stay put. In order to move it up the slope, the tension in the rope needs to be equal to the weight component plus the friction - in other words, twice the weight component. The amount of work done is thus twice what it would be if you did a straight lift over the same vertical distance - so pulling it up the slope is 50% efficient. If the friction is lower - resulting in greater than 50% efficiency, the weight will move down the slope on its own - equivalent to reversibility in a geared mechanism. And vice versa.

[Animal]

I repaired a reclining chair. It did travel when sat on with the motor not connected. Whether these mechanisms do so depends on their gearing ratio & friction. Obviously car jacks have a ratio & friction level that does not do this.