[R-390] need help with intermittent gear aka Geneva gear

Norman Ryan nnryann at yahoo.com
Sun Jan 12 23:06:01 EST 2014 

Hi, Phil,

Glad to learn the bearing is there and eliminated as a problem.

Roger's advice should help get you squared away.  Can't imagine this list functioning as well as it does if it weren't for him.

Getting the contacts to make properly involves treading a fine line.  There is lost motion in the bandswitch wafers, so you have to check in both directions; i. e., going up past the band, then going down past the band to see if you've got it right.  Slack needs to be taken up at one of the pinions that is adjustable for that purpose.

It's important that the gear clamps be snug enough.  However, there is a danger of breaking the clamp's splined bolt or the splitting the clamp itself from over tightening.  Clamps gripping surfaces should be clean of oil or grease, but the teensy bolts will tighten with less torque if you put the smallest amount of oil on the bolt shoulders and the thread where the nut goes.  

It's really hard to know how far to tighten the clamps, but the above oiling tip makes a difference.  Mobil One synthetic SAE 90 works for me -- it behaves well and tends to stay where you put it.

Getting this RF deck problem sorted out will qualify you for a black belt in R-390/R-390A overhaul.

Carry on!

Norman





On Sunday, January 12, 2014 5:59 PM, Roger Ruszkowski <flowertime01 at wmconnect.com> wrote:
 

>Phil,
>
>Knowing when and where you need the  intermittent gear aka Geneva gear
>to move is half the problem. Once you understand when it needs to move
>and to what band position it needs to move to , Getting it aligned is easy.
>
>There were some other post pointing to some other tings to also look for.
>If you are not finding the proper intermittent movement you may need to follow up on
>those points. If the intermittent movement is just at the wrong place as you dial through the 
>Mega Hertz then that's an easy adjustment. 
>
>Ten turns on the Mega Hertz shaft gets you from end to end on the counter dial.
>It drives a set of cams through their travel range.
>It drive the intermittent gear aka Geneva gear through it range.
>Setting and timing the intermittent gear aka Geneva gear is like setting a cam shaft alignment.
>But you do not get a timing mark. You do have to watch the operation of the RF band switch.
>You want that switch to move as you change the Mega Hertz shaft between mega hertz.
>You want the RF band switch to complete its operation as the Mega Hertz shaft drops into a detent position.
>You want the RF band switch to complete its operation while tuning up or down one Mega Hertz and at the proper change points.
>
>Roger 
>
>
>
>
>Roger,  thanks for the reply.
>
>Your info on getting the mega heartz detent set so that
>it is between bandswitch changes is something that I
>did not know about.  I will have to think about how to
>accomplish that as the planetary gear is the last thing
>I put in place before putting the front plate on.  At this
>point, I'm not even sure I'm getting the Geneva gear to
>go through six changes but I will look into that.
>
>As for aligning the bandswitch itself, that is no problem
>for me as I've done it before and it is clearly illustrated
>in the gear rebuild tutorial in the Y2K manual.
>
>thanks again, Phil
>
>  
>----- Original Message ----- 
>  
>From:   Roger Ruszkowski 
>  
>To: pmills7 at comcast.net 
>  
>Sent: Sunday, January 12, 2014 2:06   PM
>  
>Subject: Re: [R-390] need help with   intermittent gear aka Geneva gear
>  
>
>
>  
>Phil,
>  
>
>  
>Pull the RF deck one more time and do not put it back in until you get it   aligned.
>  
>
>  
>Stage one of two.
>  
>You want to see the intermittent gear move the band switch as the Mega   Hertz shaft is rotated.
>  
>Going up the range you need a shift from .5 to 1, 1 to 2, 3 to 4, 7 to 8,   15 to 16.
>  
>Five shifts for six octaves. 
>  
>Going down the range you need a shift from 16 to 15, 8 to 7 , 4 to 3, 2   to 1, 1 to .5
>  
>
>  
>This will be right or wrong. 
>  
>
>  
>Start in the mid range to avoid the bottom end stop on .5
>  
>As you change the Mega Hertz shaft and move the dial counter between 7   and 8 you need the band switch
>  
>to shift positions.
>  
>You need a nice clean start, shift and rest of the switch as the shaft   goes from detent stop to detent stop.
>  
>
>  
>The R390A TM and the Y2K manual show the same gear train drawing and part   numbers.
>  
>
>  
>Looking in from the bottom of the RF gear train right behind the dial   counter is a short shaft.
>  
>From front to back is a small gear a big gear (66) a clamp (71) and   small gear (79).
>  
>
>  
>If the switch is not moving at the right time and centered in motion   between the Mega Hertz detent stops.
>  
>If the motion is not quite centered going both up and down at all the   switch points, turn the Mega Hertz shaft
>  
>until the intermittent gear completes its motion. Then loosen   the clamp (71) on the small gear. Dial the Mega Hertz shaft
>  
>over to where it needs to be in a detent stop and tighten the clamp.
>  
>
>  
>You may need several shots at this to get the operation smooth and well   centered at all five of the switch
>  
>points going both up and down the range of the gear train.
>  
>
>  
>This adjustment is just to get the  intermittent gear switching   at the correct points.
>  
>
>  
>Stage two of two.
>  
>Adjusting the band switch position.
>  
>The band switch has 8 wafers with 6 positions each this is 48 contacts   that must make well.
>  
>
>  
>There is a spot between the band switch gear and the band   switch shaft where all is well.
>  
>This is an eye ball value. Do it by sight and not with a meter like   it says in the TM.
>  
>Each wafer and contact will be a bit different and not exactly   center.
>  
>
>  
>Run the gear train from end to end both up and down. Watch the switch   settings as the  intermittent Geneva gear 
>  
>settles after a shift. You may need to loosen the switch shaft gear clamp   and nudge the shaft a bit one way or another to better
>  
>ensure each switch wafer contact makes at all the points. You will eye   ball 48 contacts coming and going and then try for a best fit where 
>  
>every thing works when needed. 
>  
>
>  
>Once you get the Geneva gear moving at the right octave change points and   the band switch shaft timed for good switch contacts on
>  
>each wafer point your good on this part of the alignment.
>  
>
>  
>Phil, Just because I think this reads well does not mean that it   does.
>  
>If you have questions please put up another post.
>  
>
>  
>Roger AI4NI
>  
>
>
>  
>  
>I just can't seem to get this one right....I've got all the rest of
>the gear train set up and aligned but I can't seem to get the
>intermittent gear on the bandswitch to work correctly and the
>drawing in the manual is not much help.  I know that some of
>the teeth on the little gear between the intermittent gear and
>the bandswitch gear are longer than others and I suspect that
>these are not in sync with whatever on the intermittent gear.
>I have been told that these longer teeth are supposed to run
>up/down with the bandswitch in the 7 mc position but I've
>tried this in conjunction with what I think is the correct setup
>for the intermittent gear according to the manual drawing.
>
>I've been working with this so much that I can go from complete
>rf deck on the bench down to the intermittent gear and back 
>fully reassembled in less that 15 minutes which shows
>that I've had a lot of practice :-)
>
>Can anyone offer any help or instructions on how to get these
>gears positioned so they work correctly?
>
>thanks, Phil   W5BVB
>
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