Film-Tech Forum ARCHIVE: Century SA main drive shaft gear problem

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Posted by Mike Pennell (Member # 1692) on 05-31-2004, 09:51 PM:

I could use some help here guys. One of my projectors keeps on blowing out the main drive shaft gear. This will be my second one in the past year. What are some common reasons? Could it be a bad batch of gears? Or am i installing them wrong somehow? Thanks in advance [beer]

Posted by Mark Gulbrandsen (Member # 72) on 05-31-2004, 11:19 PM:

Mike,
Assuming that the machine isn't doing a jackrabbit start up which would definately cause undue wear on the main drive set I would replace both the fibre and metal gear together as a set. On any machine that gets alot of use or that is older this is pretty much S.O.P.. Its very likely that the metal gear at the bottom of the vert. shaft has some wear marks on it that are eating away at the new fibre gear in a hurry. This is also VERY COMMON in soundhead gearbox's that use the bronze gears.

VERY IMPORTANT.... ONLY USE AVEZZI GEARS in there... they are the best made and least troublesome by far.

While the vert. shaft is out I would disassemble it and make sure that all the wavy spring washers, cardboard washers and others are in good shape and on the shaft in the correct places. Can't tell you how many Century vert. shafts I've disassembled only to find a mishmosh of wrong washers on the shaft in the wrong places. If in doubt replace all of them as they are nickle and dime parts. Be sure all the bearings are also in good shape without excess wear and too much play. I would simply replace the main shaft bearings while you're in there.

On a second note be sure to lube them consistantly and on a regular schedule and only use SuperLube... its synthetic and holds up better than other types of grease. If you have been using something like wheel bearing grease then that may also be another cause of the gears quick demise. SuperLube is sold under the normal Century part number TU-235 by Wolk and others, its also available at any bearing supply house. The main drive gear set is the most neglected in the whole machine because you have to remove two thumbscrews to get at it..... lazy sorts and all ya know. BTW: If this projector is a hot running machine from being in front of a large xenon then lubing the main gear set every other day might be in order as the heat may be melting the grease away in a hurry.

Hope some of this helps you out......

Mark @ CLACO

Posted by Michael Schaffer (Member # 1204) on 06-01-2004, 01:12 AM:

Today I lost 2 of the fiber gears on the horizontal shaft (behind the pulley coupling it to the soundhead) on 2 Century SAs in the same location. I thought I had the correct replacement (Lavezzi GR-8). When I went to install it, I found that the horizontal shaft on our machines is thicker in the middle - the gear doesn`t go on it [Frown]

That shaft is thinner at the end where the inner bearing sits. GR-8 has the same inner diameter as the bearings. But the middle part is thicker, and the screws are bigger too.
There is no variation in shaft diameters documented in the manual. Which gear is the correct one?

Posted by Martin Risher (Member # 2453) on 06-01-2004, 01:51 AM:

i remember this one time, a guy i worked with was changing out the oil in the projector and 'forgot' to put new oil in ... didnt take long for disaster to strike like a jedi-son-of-a-bitch

Posted by Paul G. Thompson (Member # 655) on 06-01-2004, 03:23 AM:

Interesting. What are you using for lubrication of that gear, and how often do you grease it with Genuine Century Gear Lube? Is it lubed IAW the manufacturer's recommendations?

If you are using Lubriplate or some other off the wall garbage, then you will know why the gears fail.

In all honesty, the only time I had to change the gear is if some buttface forgot to lubricate it, or they used the wrong stuff. Sounds kind of harsh, I know. But lube it with the recommended stuff.

If you have been doing it, then I would like for a bind in the gear train that could be putting an excessive load on the gear. Also, as Mark mentioned, the "jackrabbit" start will really toast a gear quite rapidy.

Posted by Michael Schaffer (Member # 1204) on 06-01-2004, 03:37 AM:

Jackrabbit start?

Posted by Mike Pennell (Member # 1692) on 06-01-2004, 04:03 AM:

Everyone thanks for the replies and the help. As it turns out it wasnt the gear that the manager swore up and down was out. Nevertheless after 230 miles roundtrip to Phoenix it turned out to be a damn loose belt to the soundhead [Mad]

The moral of the story is dont spend all day working on your yard in 100+ degree heat and field problems over the phone with people who dont know the difference between a focus knob and a framing knob. Just about as bad as driving from Sacramento to Reno to change a fuse.

Michael I had that same problem a while back. I believe the gear you are looking for is the GR-302 fiber. [beer]

Posted by Michael Schaffer (Member # 1204) on 06-01-2004, 04:14 AM:

302 certainly looks like the right one (http://www.lavezzi.com/Century.html). Unfortunately the description is rather vague, and there are no dimensions given.
Basically the same as to you happened to me: I emailed a diagram of the non-operator side, tried to talk the lady on the phone through turning the individual parts by hand to indicate which is stuck or turning freely. Based on her testimony, I ordered a rebuilt intermittent, only to find it was the horizontal gear. Then I went to another location which had Century parts, took the GR-0008, only to find it wouldn`t go on the shaft... Sometimes life is simply against you.

Posted by Mark Gulbrandsen (Member # 72) on 06-01-2004, 05:42 AM:

Michael,
No, Life is NOT against you at all, life is what you make of it.

First, What you need is a dealer that knows, not that guesses at what your parts needs are and can help you over the phone in an accurate and timely manner. Secondly, you also need to get all the varations of manuals for all the equipment that you have and keep those manuals with you in your service van. I seem to recall you having similar problems with the 5 Star a while back..... Once you have all the manuals then figuring out what gear is on what machine will be quite easy. There are three distinct possibilitites for that particuluar gear depending on if you have standard drive, direct drive, synchronus or not.
Had I taken a job in Germany much as you have done here the first thing I would have done is to collect and at least somewhat studied all pertinent service data on what I would be repairing. That helps alot!!

BTW: Jackrabbit start up means to come up to speed instantly. Some older Centurys have but a small handwheel on the drive motor instead of a heavy flywheel. These particuluar Centurys can and will go through gears from this rapid start up if not corrected.
Mark

Posted by Steve Guttag (Member # 268) on 06-01-2004, 06:34 AM:

There are 5-6 varients of the Century main drive gear sets. The most popular are with the horizontal gears of the fibre variety and there are four varients of those. Two are for direct drive and two are for standard drive. The later versions do indeed have substanitally larger bores.

Steve

Posted by Jack Ondracek (Member # 1466) on 06-01-2004, 11:42 AM:

quote: Mark Gulbrandsen was the last to post
Jackrabbit start?

What happens when a Century sits on top of a Motiograph SH7500 [Razz]

...though I've seen that setup in a couple of places... no apparent problems.

Posted by Michael Schaffer (Member # 1204) on 06-01-2004, 05:10 PM:

quote:
Michael,
No, Life is NOT against you at all, life is what you make of it.

First, What you need is a dealer that knows, not that guesses at what your parts needs are and can help you over the phone in an accurate and timely manner. Secondly, you also need to get all the varations of manuals for all the equipment that you have and keep those manuals with you in your service van. I seem to recall you having similar problems with the 5 Star a while back..... Once you have all the manuals then figuring out what gear is on what machine will be quite easy. There are three distinct possibilitites for that particuluar gear depending on if you have standard drive, direct drive, synchronus or not.
Had I taken a job in Germany much as you have done here the first thing I would have done is to collect and at least somewhat studied all pertinent service data on what I would be repairing. That helps alot!!

We have a really good dealer who always orders the correct parts and I do have all the documentation (or most of it, there`s always something you don`t have). They also have most of the parts in stock. The problem we had on this weekend wasn`t that I ordered the wrong part or the dealer sent the wrong part, it was simply that it was Saturday late at night, I knew we had a couple of spare gears in one location, it was just bad luck that those were the other gear.
Since we have an enormous variety of equipment - it is a young company formed from locations taken over from other exhibitors - it is quite impossible to stock all the parts we might need. I have most of the parts commonly used on our equipment, but there is always a situation where others go out.

BTW, I don`t see the various gears documented anywhere in the Century parts catalog. Did I overlook it or is it simply not documented? I remember I went through the catalog and wanted to order these gears as spare parts because they are fiber. But it looked to me like there is only one version and since we already had some of the gears (the GR-0008), I decided against getting more.
The problem I had with the 5Star soundhead idler was also something not documented in the parts catalog. Once we had figured out what parts to order, Strong sent us the wrong parts in the first shipment, incomplete parts in the second without marking them as backordered. It wasn`t the dealer`s fault - I saw that he had ordered the correct parts.

Posted by Mark Gulbrandsen (Member # 72) on 06-01-2004, 07:20 PM:

Michael,
There are a number of different SA manuals available and they do cover the differing drive arrangments. Best to call your "Dealer" and get them from him, he ought to know. Now that you know the differences in the machines somewhat you can go through these manuals and order the correct spares. Its a good idea for you to stock at least one of each gear in your own spares kit and perhaps one or more in strategic locations so you can get to them in a hurry. The other option is to convert them all to one type of drive setup, a bit pricey but it might save some down time on a busy weekend and allow you to make money instead.

Mark

Mark

Posted by Michael Schaffer (Member # 1204) on 06-01-2004, 11:16 PM:

I`ll rather stock the different gears. We only have 4 Monees and 7 Centuries anyway, the former use the small bore gear, the latter the large bore.
Just out of curiosity: where in which part manual are the different shafts reflected? I actually looked through all the manuals for all the different equipment we have before coming here, especially in order to be prepared for such pitfalls. But I never found the different shaft sizes of the Century listed anywhere. I also never found a crossreference list for original and Lavezzi parts anywhere.

Posted by Paul G. Thompson (Member # 655) on 06-02-2004, 12:14 AM:

Jack, you should see that Cinecita start up that is in one of the houses in Post Falls. MAN! It starts with a WHAM!!!

I am amazed that the gears are not laying on the floor yet.... [Big Grin]