Film-Tech Forum ARCHIVE: Brenkert Binding

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Posted by Mike Lauber (Member # 1486) on 08-07-2003, 03:08 AM:

I am having trouble with a Brenkert projector suddenly binding up. Everything is oiled properly. When I start the motor, it has to struggle to get the projector moving, but once it's moving, it runs fine. The projector even continues to roll freely for several seconds like normal once the motor is turned off. It also is difficult to advance the projector manually. I separated the soundhead from the projector, and the motor and soundhead ran just fine, so I know it's a problem in the projector. Any ideas of what I should try?

Posted by John Anastasio (Member # 607) on 08-07-2003, 06:25 AM:

What kind of soundhead are you using? Does the motor get excessivly hot while the machine is running, or does this problem only occur at startup? Is there a lot of free play in the soundhead gear train? Despite the wonderful oil bath on the drive train, the sprocket shafts on the operator side need to be lubricated or they'll get gummy, then free up a bit when things get warm. I've got a BX80 and a BX60 and have never had one bind on me, but have had trouble with the drive gears.

Posted by Barry Floyd (Member # 385) on 08-07-2003, 09:28 AM:

If you've recently pulled out the main drive gear and shaft on the projector, it's possible you may have not got it seated properly back into place. That happened to my BX-60. The shaft has a flat spot on it that corresponds to a set-screw that is acessed from the rear of the machine (under the shutter housing).

My set screw had worked loose, and the damn shaft and gear kept coming out of the machine while running, disengaging it from the soundhead. When I first put it back in, I didn't get it set right and the projector was a little stiff to turn over by hand. My other BX-60 just glides like butter. Once I re-installed the shaft with the flat spot properly lined up... the problem went away.

It's worth checking out anyway....

Posted by Tim Reed (Member # 137) on 08-07-2003, 01:37 PM:

Mike, did you just change the oil in it? Brenkerts don't like anything thicker than transmission fluid.

Posted by Paul G. Thompson (Member # 655) on 08-07-2003, 06:28 PM:

BX-40, BX-80, and BX-100:

Make a comparison. Manually advance the machine with and without film in the trap. If you feel a significant change, loosen up on the film trap pressure pads. I have seen some so tightly screwed down that the intermittant sprocket shreads the film.

Reset your frame knob to center. Sometimes the big thick gear that slides on the shaft of the bevel gear will cause some binding. Check for binding in the compensator, also. And, naturally, the intermittant movement. Yank the movment out of the machine and see if the binding goes away.

It is just a matter of isolation. Yes, what kind of oil are you using, and is it clean? If you have a BX-60 and the oil is black, the intermediate gear bushing failed.

If you like, you can start the machine for testing for binding. However, put the gearcase cover back on before you do that unless you desire an "oil bath." [Big Grin]

Posted by Phil Hill (Member # 371) on 08-07-2003, 06:37 PM:

What type of motor? Sync type? Induction type?

It may be a problem with the motor's starting circuit/centrifugal switch/starting capacitor rather than a mechanical problem.

It may start OK under the light load of the soundhead, but with the projection head adding to the load, it may have a difficult time to start that additional load.

>>> Phil

Posted by Paul G. Thompson (Member # 655) on 08-07-2003, 06:44 PM:

Another thing to check is the possibility of a very badly worn gear in the soundhead (RCA or Simplex). The gear that usually fails is the one on the constant speed sprocket. If there is a load on it from the projector, the soundhead pinion shaft will probably climb the gear and cause a nasty bind. Without the projector loading, it just might spin just as free as can be.

Check your soundhead oil. If it is black, your bronze gears are shot and might cause the binding under load. Drain the oil from the soundhead and check for bronze contamination in the form of chunks. Stick a long "Q" tip in the drain hole to get a sample of the sediment in the gear box, and look for gear teeth imbedded in the Q-tip end.

Posted by Bob Peticolas (Member # 328) on 08-08-2003, 03:09 PM:

We had this exact same thing happen after an oil change. It was a brand new can of Brenkert oil. But the viscosity was wrong, very wrong. We had to "warm up" the projector for about five minutes before the show to get it to run smoothly. Once warmed up it ran fine.

The solution was to drain it completely and refill with the correct oil. The distributor said that the mfg. of the oil goofed and shipped the wrong oil in the right cans. Once the oil was changed, everything was back to normal.

Posted by Sam Hunter (Member # 1119) on 08-08-2003, 03:35 PM:

Bob, where did you get that oil from and what kind of container was it in?

Posted by Paul G. Thompson (Member # 655) on 08-08-2003, 10:42 PM:

We had someone try to dump a quart of soundhead oil in a theatre up here. Turned out to be EP-90 gear oil. I suppose that can happen with projector oil, too.

Besides, for the Brenkerts, go get a 5 gallon bucket of Chevron Anti-wear high speed hydraulic oil ISO 10. It is the suggested replacement for AMOCO Spindle Oil "A." It only costs about 35 bucks. The orginal Brenkert Oil I think was Mobil ISO-10, which crossed to Amoco Spindle Oil "A".

Posted by Bob Peticolas (Member # 328) on 08-10-2003, 11:17 AM:

Sam,

It came from my supplier in a one gallon can with Brenkert labels on it. By that I mean the label said "for use in Brenkert projectors". My supplier said it was a manufacturer's mistake, the replacement can was exactly the same, but it contained the correct oil.

If you're interested, I can get you exact details when I go to the theatre later this morning.

Posted by Bob Peticolas (Member # 328) on 08-10-2003, 03:08 PM:

Here are pictures of the can with the supplier's label and the manufacturers's label (after I peeled off the supplier's label).

I tried cross-referencing these oils and got lost in an oil field of brands, viscosity's, and cross references that didn't match each other.

We change oil every six months or so thus our needs aren't that great. A gallon lasts about four years at one pint per oil change.

Can with distributor's label

Supplier's label

Posted by Paul G. Thompson (Member # 655) on 08-10-2003, 11:58 PM:

I would guess you had the right oil. However, I don't have my petroleum manual handy to see what viscosity it is. Since it is hydraulic oil, it is probably ISO 10, maybe 15. If you shake the can up, it'll sound like kerosene sloshing around in it. That is usually a good sign.

Posted by Steve Kraus (Member # 476) on 08-11-2003, 07:01 PM:

At least they're not making any secret as to what it is. Unlike the dealer who would buy a single drum of oil and transferred it to small cans labeled Simplex, Century and Ballantyne. One for all and all for one.