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One Way Bearing Usage

10/22/2016 2:53 AM
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I am developing a motorized cable reel. I am using a geared DC motor to drive central cable drum on which the cable rests. This cable reel is only used to automatically retract the cable back once the cable is pulled out. The cable is pulled out manually by hand from the cable reel.

I am using a one way bearing coupled to my DC motor shaft to make it easy to pull out the cable manually. The one way bearing housing is in turn connected to a small sprocket. The small sprocket is connected to the bigger sprocket (attached to the cable drum) via a chain.

Now, the problem that I am facing is that the whenever I power on the motor, the entire assembly rotates in the direction that the one way bearing moves. But what I need is the assembly needs to rotate in the direction opposite to which the bearing moves. On the side where the bearing rotates freely , I pull the cable out manually (as the bearing makes it easy to pull cable out), and I dont turn on the motor in this case. In the other direction where the bearing doesn't move, I need the entire assembly to rotate in order to pull the cable in, but what happens is that just the motor shaft rotates, the bearing, bearing housing, sprocket, etc dont move.

What modifications should I make to achieve my goal or any other alternatives for this ? I cannot use an electromagnetic clutch here.

Also, below is the link to a video where I explain the problem I am facing. problem explanation video

Also, the one way bearing is connected to the motor shaft via a keyway slot on the bearing and a key on the shaft. I am trying to use the same cycle chain and sprocket concept here and I am trying to understand where I am going wrong here.

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Pathfinder Tags: bearing gears motor torque
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#1

Re: One way bearing usage

10/22/2016 4:01 AM

If you're playing tug-o-war and the other guy (or machine) is stronger than you are, the only way you can win is to get the other guy to let go of the rope.

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#2

Re: One way bearing usage

10/22/2016 8:57 AM

I believe you have your thinking muddled here.

A free-wheel mechanism will never work as you want it to in this application.

Consider a bicycle - when power is applied to the pedals, the bike moves forward - this is analogous to driving the motor and spooling the cable off the drum.

When the pedals are held stationary, the bike continues to move forward - this is analogous to stopping the motor and pulling the cable off the drum.

In either case, cable comes off the drum.

With a normal free-wheel mechanism, no amount of pedaling backwards will make a bike go backwards.

I think a slipping clutch would be more appropriate in this application.

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#3

Re: One way bearing usage

10/22/2016 8:58 AM

An over-running clutch (which is what your 'one way bearing' is won't work for what you're trying to do.

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#4

Re: One way bearing usage

10/22/2016 10:09 AM

What you need is a pawl and ratchet assembly...

https://www.google.com/patents/US6431525

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#5

Re: One Way Bearing Usage

10/22/2016 11:53 AM

Save yourself lots of headaches.

Keeper 0.7‑Hp 2,000‑Lb ... $85.31 Lowe's 12 Volt Utility Winch ‑ 2000‑... $62.99 Northern Tool (63) Arksen© Electric Wire ... $239.97 Jet.com Cabela's Electronic ... $89.99 Cabela's Special offer

Trac Electric Anchor Winch ... $102.13 Walmart (38)

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#6

Re: One Way Bearing Usage

10/23/2016 11:48 AM

Isin't that like the spring powered hose reel the guy at the filling station uses to fill up your tires ?

Since the present one doesn't require a motor or electricity for operation, why do you think someone would want one that they would have to plug in ?

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#7
In reply to #6

Re: One Way Bearing Usage

10/23/2016 4:01 PM

No plug in - it will be cordless - just like everything else is today.

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#8

Re: One Way Bearing Usage

10/24/2016 12:35 PM

http://www.trci.net/products/shoreline-reels/cord-reels-rv-marine/50-amp-rv-power-cord-reels-rh54-rl54

I have something like this in my RV. I manually pull out the cable and it freewheels off the drum and then to retract there is a momentary contact switch that powers the return.

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#9

Re: One Way Bearing Usage

10/24/2016 8:09 PM

Sounds like you need to turn the 'bearing' 180 degrees in the shaft so it clutches in the opposite direction....

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#10
In reply to #9

Re: One Way Bearing Usage

10/24/2016 9:24 PM

That would just defeat movement in the other direction. The cable needs to go in both directions, which a one-way bearing cannot accommodate, unless there is a clutch or some other mechanism to allow operation in the other direction.

Post 1 was right on target, but was somehow voted OT.

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#11

Re: One Way Bearing Usage

10/24/2016 9:53 PM

Hint: Coaster brake.

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#12

Re: One Way Bearing Usage

10/25/2016 8:25 AM

A centrifugal clutch on the motor?

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#13

Re: One Way Bearing Usage

10/25/2016 2:28 PM

No. go buy an actual motorized cable reel. What you have is balderdash.

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#14
In reply to #13

Re: One Way Bearing Usage

10/25/2016 4:04 PM

You forgot "bunkum".

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#15
In reply to #14

Re: One Way Bearing Usage

10/26/2016 10:34 AM

Oh, thanks for the reminder. Bunkum is seriously the correct word for trying to southern engineer a contraption when Harbor Freight even has a better one to purchase for $59.95.

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