Help with Postwar Lionel Plastic Knuckle Couplers

The spring won’t break.  Just inset the knuckle in coupler, slide the rivet in, flip it over and expand the rivet with center punch.  Have installed about a thousand that way.  The spring will actually last longer if stored in the open position when not in use.

I wonder if @Tim Ring is referring to the type of all-in-one Delrin knuckle I have seen a few times in the past, part number 566-27. Instead of having holes thru the knuckle for a rivet to drop through, these had solid pivot points with dimples protruding on the top of the upper mount and on the bottom of the lower mount. The dimples would then just snap into the holes on the coupler body where the rivet holes are.

This part appears to be like seriously extinct - and probably not a very good replacement option just because they would pop out or break frequently. A better solution is one that Rob offered about 17 years ago, "For best operation(and durability), I replace the broken plastic knuckles with the standard 480-8 cast knuckle,  480-16 knuckle coupler spring, and the black TC-23 knuckle rivet available from some parts dealers."

This certainly provides a more reliable and smooth operating solution.

George

@GeoPeg posted:

I wonder if @Tim Ring is referring to the type of all-in-one Delrin knuckle I have seen a few times in the past, part number 566-27. Instead of having holes thru the knuckle for a rivet to drop through,..

Well, that's not the one he's showing, but based on his description the one I posted instructions for. I guess we'll have to wait for Tim to come back and see if he meant "replacement knuckles with integrated springs, and (replacement)rivets" or how I took it, as "replacement knuckles, with integrated springs and rivets".

Thanks guys for the help.  The replacement parts came with a stainless rivet.

After reviewing the post by GeoPeg,  these cars do come with the all Delrin knuckles that GeoPeg has described.

Between the two pivot points at the top and bottom of the coupler head, there is a very small spring-like bracket  with two prongs.  The prongs fit inside the bottom of the top knuckle hole, and the top of the bottom knuckle hole. The replacement knuckle has to fit between the two prongs which would then hold the replacement knuckle in place.  Therefore, the two prongs have to be spread apart to insert the replacement knuckle.

The plastic spring attached to the replacement knuckle (see my photo in original post) has to be squeezed against the knuckle in order to be inserted inside of the coupler.

I have not yet mastered the required technique in order to spread the bracket, and insert the replacement knuckle while squeezing the spring at the same time!

This style of coupler does not utilize a rivet to secure the knuckle to the head.  A rivet cannot be used because the spring-like bracket blocks the path of the rivet through the coupler head.   

Yikes!

@Tim Ring posted:

Between the two pivot points at the top and bottom of the coupler head, there is a very small spring-like bracket  with two prongs.  The prongs fit inside the bottom of the top knuckle hole, and the top of the bottom knuckle hole.

Well that rather solves the mystery.  Part of the old knuckle is still in the coupler, you need to remove that "small spring-like bracket" by snapping it out of the two holes & discarding.

Rob,

I compared the couplers with the missing knuckles to the other cars in the same set with the same trucks and couplers.  None of the unbroken operating couplers have a rivet. They all have the spring-like bracket instead.   

See attached photos of an unbroken operating Delrin coupler.

@Tim Ring  ... There are only 2 pieces of plastic in those coupler pics, the truck bolster with the coupler frame/chassis, and the knuckle, which includes the thumb, spring, and pivot all in one snap-in piece. Your intact coupler can be disassembled by squeezing the pivot nubs toward each other and sliding out the entire piece - there is no extra spring-like bracket - it is part of the knuckle and your broken one has half of it still in the coupler pocket with its nubs still holding into the rivet holes. You need to remove what's left of the old knuckle before the new one can be installed. Here is what the knuckle looks like as removed:


There were two versions of the integrated knuckle:

Be sure to dunk the end of the truck in hot tap water before you proceed, ….as hot as you can get it to run out the tap will be fine, ….this will allow you just enough wiggle room to get the old parts out, and the new part in,……Lionel spells that out in the instructions posted above by Rob, ……just wanted you not to omit that step,…..bad things can happen otherwise,…..😩😩😩

Pat

Good practice on all the couplers with the plastic springs is to leave the coupler in the open position when not in a train. The plastic takes a set with age and also becomes brittle. Leaving them open just extends their a life a bit.

Pete

Rob,

I was able to remove the piece of coupler as you described.  Attached are pictures of the removed piece.

Once removed, I was able to install the new knuckle using the rivet.  Now I have to go buy a center punch to set the rivet.

Thanks to you and to all who responded to help. I appreciate it.

Tim