Film-Tech Forum ARCHIVE: Correct gear replacement Simplex XL

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Posted by Frank Angel (Member # 248) on 02-06-2007, 10:03 AM:

We had to have some gears in a Simplex SH1000 replaced because of an oil tube that was showing good oil level when actually there was none in the unit (the tube gets clogged -- simple thing but devastating if you're not aware). The brass gears stripped.

Anyway, when the unit came back from being refurbished, the fiber transmission gear (from soundhead to mechanism) makes a rather nasty whining noise. Another projectionist said that there were actually two different transmission gears, nearly identical, for that soundhead -- one to mate with the Simplex XL head and another for a Century. They look so similar that you can't tell the difference by looking at them. If they put the wrong gear in there, it will sing like the fat lady.

He said he's been in a booth where both projectors had the wrong gear and they ran them that way for the entire three years he was there and, aside from how loud the booth noise was, nothing bad happened.

In our case, you would think you would see some image vibration or possibly a wow/flutter in the sound given the nasty noise this thing makes, but everything looks fine, which kind of verifies my friend's experience.

Does anyone 1) know if indeed there are different gears for this soundhead and if so, what might be the part number for the correct gear for a Simplex XL head? And 2) how much damage, if any, can I expect from running with the wrong gear?

As you can see, the Simplexes seem to be conspiring to giving me noisy headaches this week.

Posted by Gordon McLeod (Member # 33) on 02-06-2007, 10:21 AM:

The only difference is the gear on the projector head ( a xl on a SH1000 compared to a XL on a RCA)
The gear on the soundhead is the same
I bet that it is a issue of gear mesh either it is misaligned or to tight (try back the machine towards the lamphouse by a 1/2 turn of the screw on the front) or that the mesh is not the same as it was and has to run in

Posted by Dave Macaulay (Member # 813) on 02-06-2007, 11:44 AM:

Well.
The SH1000 gear/pulley is always the same like Gord says.
A Century on an SH soundhead drives without any idler and the projector gear for it wouldn't work on an XL, so your buddy's story is a bit suspect.
The projector drive gear and the idler gear have to match the soundhead gear, which doesn't change on the soundhead to accomodate projectors.
The RCA and Western Electric soundheads that drive the XL pretty much the same as the SH1000 have various different gear pitches or angles, and you would have a problem if you used their idler and/or projector gears with an SH1000.
Normally when refurbishing a soundhead one wouldn't even see the XL projector drive gears since they're attached to the projector, did you have the idler or drive gear replaced?
The XL projector drive gear (on the projector shaft) for an SH1000 is PN P-1539. The XL/SH1000 idler gear is G-1826. The SH1000 large steel drive gear/pulley is SN-259.
You can find the drive kit parts listed in the projector parts book.
If either or both of the 2 projector gears were wrong - projector or idler - it would sound pretty bad I guess. Probably the fiber or plastic idler gear would get ruined in any case, the steel gears should be OK.
The most likely problem is too tight or too loose meshing of the gears. Loosen the projector head and push it away from the soundhead gear then set the idler mesh against the projector gear, there should be a slight play through a whole turn. The soundhead/idler mesh is set by moving the projector, same deal with a bit of play through the full turn. You can adjust it by sound if you're brave, set the hold-down bolts snug and tap the projector fore and aft gently until is stops whining from being too tight. If the adjuster screw is still there (rather too often it disappears) make sure it allows a bit of play, you can shift the projector one way with it if you so desire.
The SN-259 soundhead gear may have been damaged somehow too in shipping.

Posted by Mark Gulbrandsen (Member # 72) on 02-06-2007, 05:14 PM:

Frank,
When ever you trash a bronze gear by lack of oil or excess load be sure to also replace the pinion. If you examine the face of the gear teeth on the pinion that was run under those conditions you'll see they resemble tiny saw teeth.....

Mark

Posted by Steve Guttag (Member # 268) on 02-06-2007, 06:10 PM:

I do agree that too often the pinion is not replaced when it has sharpened and you get horrible life out of the next set of expensive bronze gears. Replace the whole set and keep it properly lubricated and they seem to have a near indefinate life. Use too thin an oil or leave a worn part in and it isn't too long until you are back cracking open the case again.

Posted by Frank Angel (Member # 248) on 02-07-2007, 03:05 AM:

Yes, we replaced the pinion as well. And he did tell me that once the teeth get sharp the whole thing can grind into a bronze powder in a matter of minutes. And I believe one, possibly two fiber gears in the projector head had to be replaced well because when the soundhead went, damage went further up the line.

And I misspoke -- it wasn't the Century soundhead but an RCA that he said would work but wouldn't cause serious damage.

We'll see -- today he called and said I could pick up the right one from him. I will check those numbers Dave (thanks) and make sure all the gears are correct and where they are supposed to be.

Posted by Louis Bornwasser (Member # 3063) on 02-07-2007, 08:46 PM:

Besides the gear mesh (sliding motion) it is possible that the projector is slightly twisted. Some xl's don't have the slight indentation which the bar drops into when you assemble the bar to the bottom of the projector. Barely loosen the two screws that mount to the xl bottom and reinstall. "Hug" the xl twisting slightly for min. whine; disassemble and tighten screws, then reassemble and set mesh.

Add this info to those rca/simplex thoughts above. Louis