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Join Date: Mar 2011
Posts: 34

Continuously Connected - How Is It Done?

11/26/2017 3:05 AM

Hi all,

We have this handwheel in our plant, and until now we use it only for limiting the higher position of the travel. But according to the operation instructions (page 7), paragraphs 2+3, the handwheel is continuously connected to the actuator stem, and by turning the handwheel to the right (or left) the actuator stem moves downwards (or upwards).

The process does not allow for a blank test, at least not in the next months.

When the handwheel stem is in neutral position (e.g the top of the screw alligns with a red line visible through the cap), then (as I understand) the handwheel is disengaged from the actuator stem, and no more continuous connection is possible.

In paragraph 5, it says that any other (than neutral) position, provides only a limiting function, limitiing either opening or closing.

Question1: How can paragraph 5 be true (provide only limiting function), and paragraphs 2+3 be also true (continuous connection between handwheel and actuator stem) ?

Fig. 3 (page 8) shows the following:

the angle gears iside gear operator (item 393). The angle gears transmit the rotation from the handwheel to the handwheel nut (handwheel nut is not clearly indicated, but it is located between the two axial bearings)

the handwheel screw (item 388). When handwheel nut is rotated, then handwheel screw moves up or down. So far we have a continuous connection.

the handwheel stem (item 380)

the stem key (item 373)

Question2: Does the stem key allow a linear (up and down) relative movement between the screw and the handwheel stem? If yes, then what causes the handwheel stem to move up and down?

Question3: Does the rotation of the screw (when someone turns the handwheel) passes (through the stem key) to the handwheel stem, or not?

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Pathfinder Tags: handwheel linear actuator
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#1

Re: Continuously connected - How is it done?

11/26/2017 8:31 AM

Gee, it's too bad we don't have the picture in front of us.

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Associate

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#2
In reply to #1

Re: Continuously connected - How is it done?

11/26/2017 9:52 AM

Let me try upload the fig.3

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#3

Re: Continuously Connected - How Is It Done?

11/26/2017 10:01 AM

To return the valve to automatic control, return the handwheel nut to 'neutral' as shown by the hand-wheel position indicator and set the three-way bypass valve to 'auto.' The neutral position is indicated when the top of the screw aligns with the red line on the cap liner. 5. Adjusting the handwheel nut to a position other than neutral provides a limit stop function, either limiting opening or closing.

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#4
In reply to #3

Re: Continuously Connected - How Is It Done?

11/26/2017 10:32 AM

So that is why I ask my question1, ( and then my other 2 questions)

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#5
In reply to #4

Re: Continuously Connected - How Is It Done?

11/26/2017 11:01 AM

1. The hand wheel stop prevents mechanical damage to the mechanism or valve by limiting the valve movement. The mechanical advantage of the screw/gears would allow a careless operator to damage the mechanism if not equipped with stops. The actuator system does not produce sufficient force to cause damage to the valve,

2 Gears

3. Yes

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#6

Re: Continuously Connected - How Is It Done?

11/26/2017 12:33 PM

Thanks lyn.

After reading your answer I realised that I have to delete my question 3. The screw does not rotate, it only moves up or down. Only the handwheel nut rotates, causing the screw to move up or down.

And as the screw moves up or down, it causes (through the stem lock nut) the handwheel stem to move up or down.

So, from the gears, the rotational movement is being transmitted to the handwheel nut, and from the nut the movement is transmitted to the screw, which moves only up or down (no rotation). From the screw, through the stem lock nut, the linear motion is transmitted to the handwheel stem, and from the handwheel stem, through the stem pin, to the actuator stem.

Ok, there is continuous connection, unitl now.

What happens in the neutral position, and the handwheel stem provides only a limiting function? Which part of the above description of coninuous connection is disengaged, and how?

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#7
In reply to #6

Re: Continuously Connected - How Is It Done?

11/26/2017 1:21 PM

"What happens in the neutral position, and the handwheel stem provides only a limiting function?"

It doesn't.

From the manual:

"Adjusting the hand wheel nut to a position "other than neutral" provides a limit stop function, either limiting opening or closing."

Your assumption that the gear assembly can transmit rotation to the hand wheel is also incorrect.

You seem to me to be worried about a very small, unimportant detail!

Do not over think a properly working valve!

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#9
In reply to #7

Re: Continuously Connected - How Is It Done?

11/29/2017 11:29 AM

Thanks Lyn.

I am still trying to understand the connection of the various components in "neutral position" of the handwheel.

English is not my spoken language, so what sounds normal plain English to you, may need some explanation to me.

I would aprreciate if someone describes the various parts position in the neutral position, using (and correcting or adding ) my explanation "So, from the gears, the rotational movement is being transmitted to the handwheel nut, and from the nut the movement is transmitted to the screw, which moves only up or down (no rotation). From the screw, through the stem lock nut, the linear motion is transmitted to the handwheel stem, and from the handwheel stem, through the stem pin, to the actuator stem."

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#11
In reply to #9

Re: Continuously Connected - How Is It Done?

11/29/2017 4:17 PM

You said originally, "In paragraph 5, it says that any other (than neutral) position, provides only a limiting function, limiting either opening or closing."

You have misread this sentence. The manual does not say "only"!

It says, "Adjusting the hand wheel nut to a position other than neutral provides a limit stop function, either limiting opening or closing."

As I labored futilely to explain earlier, normal (non-hand wheel) operation of the valve is self limiting.

Here's another (humorous) explanation.

Adjusting the hand wheel nut to a position other than neutral causes a miracle to happen and the valve can then be operated by the hand wheel. The same miracle also provides a limit stop function, limiting opening or closing to prevent damage to the valve by the mechanical advantage of the hand wheel gear torque multiplication.

Unless repair, periodic maintenance and adjustment of this and other valves is your primary responsibility, just go with the explanation above and find something, anything, more productive to do.

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#12
In reply to #11

Re: Continuously Connected - How Is It Done?

11/29/2017 4:53 PM

This miracle must be hard for you to descibe! Unless you want to give a helpful answer, please don't waste your time advising me what to do.

The manual does not say "only". You are right. Does this mean that it provides limit function as well as continuous connection?

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#8

Re: Continuously Connected - How Is It Done?

11/27/2017 1:16 AM

Is there a problem with the valve?

If there is a problem with the valve, why not contact the manufacturer/supplier?

Have you called the manufacturer/supplier?

If you just want to know how the valve works, why not contact the manufacturer/supplier? They have more literature.

Have you called the manufacturer/supplier?

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#10
In reply to #8

Re: Continuously Connected - How Is It Done?

11/29/2017 11:37 AM

Thanks Mikerho.

No problem with the valve. As you say I am trying to understand how the valve handwheel works. The manufacturer has given the instructions in the manual, but I seem to miss some important detail. I think CR4 members would easily explain this.

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cosv001 (6); lyn (4); Mikerho (1); Tornado (1)

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