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**Yellow Duck** · 01-12-2006, 04:07

Re: Rear Trim pulley, dimensions anyone?

Bill, I have almost a simular problem, but the front pully overhead at the crank. It slips constantly. I keep adjusting it. I keep thinking I may need to add tentison to the cable (?).

Suggestions here tribe ?

**mulwyk** · 01-12-2006, 05:46

Re: Rear Trim pulley, dimensions anyone?

Lee:
I believe Rob Lees has a special spring to hold tension on the trim

Bill:
I'll check my trim pulleys this afternoon, make a drawing and scan it in (I hope) this evening.

Bob Gustafson

**crispy critter** · 01-12-2006, 06:15

Re: Rear Trim pulley, dimensions anyone?

Graphite on the cable will help....also they must have a spring for tension to work properly, without the spring it doesn't allow the cable to change it's own length to allow for the difference when the elevators change positions. Never use penetratingoil or any type of wet or slick lube for the trim cables & pulley's...always use the graphite, otherwise you will never get it to stop slipping.

**Yellow Duck** · 01-12-2006, 06:19

Re: Rear Trim pulley, dimensions anyone?

Kevin, think that is where I messed up. Oiled the pulley shaft and must have gotten oil on the cable. Thinking about putting some paint thinner on a rag and wiping the cable then putting grafite on. Think that may help ?

**Sloanlow** · 01-12-2006, 08:19

Re: Rear Trim pulley, dimensions anyone?

Tribe

I just ordered and received a new rear trim pulley from the factory. It was diminsionally perfect and they sent a new locking pin with it. It was a measly 19 dollars I believe.

Jim Allison

**1948TCARTDRIVER** · 01-12-2006, 08:27

Re: Rear Trim pulley, dimensions anyone?

I had the same problem on my 48 when I first got it, my rear trim pulley was pretty chewed up. I made a new pulley out of phenolic, using the same dimensions as the old one, but I used a "v" groove down the center. I believe this gives the cable more bite. My aircraft also has a spring to maintain tension, it is located in the overhead aft of the baggage area. Another area to watch is the elevator control horns, if they are pulled in at the elevator cable attach they can drag on the trim pulley. It is a pretty simple system and works well if all the parts run freely. My system is now pretty trouble free, I'm careful not to get any lubricants on the cable at annual time. I also avoid using the trim unless the elevators are near neutral, other wise the trim cable will drag on some of the fairleads.

Keep em flying

**M Towsley** · 01-12-2006, 10:26

Re: Rear Trim pulley, dimensions anyone?

Lee,

When I first got my plane I noticed the trim was difficult to move, so I sprayed some lube up in that area. It was difficult to get to because of the headliner so I apparently got it everywhere. Everything moved really well after that, including the pulley over the cable. I had to clean, clean, clean and then regrooved the pulley so it would bite. The resin helped along with the regrooving and everything works, except it is still stiff. I will one day probably have to go into the elevator and clean that up, which I am guessing may be where the stiffness is coming from. I also found out there is a sweet spot on cable tension, not too loose, not too tight. Just experimented over time and so far, so good.

**hangarb7** · 01-12-2006, 10:40

Re: Rear Trim pulley, dimensions anyone?

Ditto on the sweet spot, Marty.

I needed to fix the trim cable guide in the tail which meant disconnecting the cable and then rethreading it back around the pulley.

The cable accidentally dropped over the side of the pulley at one point and picked up some lubricant from the shaft. After I got it put back to the exact spot where the cable was attached with the "bug" at the spring, it slipped like crazy. Started playing with the tension on the spring and at one point, it was working until is reached the extreme position then wouldn't come back, only slip.

I played and played with it and finally it works very nice, just like before. But it was all in the tension; of course after you are certain that it works freely and there is no lube to complicate matters.

I would play with the tension until it works OK, then add the antislip stuff.

Jack D.
N44057
'46 BC12D

**high time cub** · 01-12-2006, 10:58

Re: Rear Trim pulley, dimensions anyone?

Ok, all you rivet counters avert your eyes.
Feed some masking tape into the pulley groove (under the cable) as you crank the trim handle 1-2 turns. I did this to my 15000 hour Cub in 1978 and 1000 hours later, it's working just fine! Just the right mixture of paper, mastic, and phenolic dust to make the cable grab. I've suggested this simple fix to several T-Craft and Cub owners, and reports from the field indicate a high level of success. Keep in mind, these old crates are a flexible marriage of materials: glues, tape, wood, fabrics, steel, semi-dry varnish/ linseed oil, string, wax, cork, shellac, and so on. May as well add a few inches of masking tape.

**Forrest Barber** · 01-12-2006, 14:43

Re: Rear Trim pulley, dimensions anyone?

The NOS rear pulleys ( B12-461) here at Barber Aircraft or Foundation are $10.00 plus mailing..... $4.50 for two day or $1.00 in an envelope. always had them since Lock Haven days....all the other advice is good, keep em clean , keep the screw & bolts lubed. The pulley is really a V cut so the cable does not bottom out and slip...

**Robert Lees** · 01-12-2006, 17:34

Re: Rear Trim pulley, dimensions anyone?

There are some good pointers on this thread (the masking tape sounds a great idea!). My own pulleys have a sharp groove (to prevent the cable running on the bottom of the groove...running a mini hacksaw blade around the groove might help). And I use no grease, only Rosin, as already mentioned.

I also have my own drawings of both the fore and aft trim pulleys...I will try to scan in tomorrow & post for comparison.

Forrest has always been very kind to me with his pulleys, so go that route first, I suggest. Also, his comment about trim screw lubrication is always worth adding to...I have photos of the lube hole on one of my web pages here about 3/4 of the way down the page.

Incidentally, the tension spring referred to by Bob, is a new manufacture stainless shot-peened spring, manufactured by the same US company that produces springs for airbag triggers. I assume that they cannot permit a great failure rate!

Anyway, I have a few spare: to conform with FAA "owner produced parts" regulation, any purchaser would need to be involved in the "quality control" of said part...i.e. they would need to be satisfied it meets the same characteristics and does the same job as the original.

**Bill Weiser** · 01-12-2006, 17:55

Re: Rear Trim pulley, dimensions anyone?

Thanks for all the good input on the rear trim pulley. I have no head liner so all is exposed, so I know when the trim cable tension spring hits the frame stop, which is quite often these days. I also think maybe the threads of the mechanism in the left elevator may be gummy (winter months were always worse than heat of the summer). Unfortuately, the last one to recover, did not put in an inspection port. 1) Is the inspection port in the elevator in this area standard? 2) Is it usually top and bottom? 3) Does anyone have cicrle center line measurements for cutting a port in. Or, perhaps it is possible to clean and regrease this thread interface by removing the elevator (without the inspection ports)? Experience or thoughts out there.

**mulwyk** · 01-12-2006, 20:50

Re: Rear Trim pulley, dimensions anyone?

Attachment shows my trim pulleys measured with the aid of .093 and .062 drill bits. The groove looks like a radius at the bottom rather than a "V", probably due to wear.

Bob Gustafson

Attached Files

**flybikefarm** · 01-12-2006, 21:05

Re: Rear Trim pulley, dimensions anyone?

forrest; how about the other pulleys? i need four large and two of the small for the control system george

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Rear Trim pulley, dimensions anyone?

Rear Trim pulley, dimensions anyone?

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