Thompson buffer stocks

[Bill Bedford]

Daft question: what stops the collar sliding around in use and dropping off?

There is an extension on the end of the collar that fits into the flange on the ram. It shows clearly on the first of the two drawings above.

[riley]

Thank you so much. These pictures and drawings are useful and educational. I had no idea that in extended position the buffer was held in place with a collar and chain and in normal retracted position the collar was clipped to the end of the carriage. I'm tempted to affix a bit of plasticard to the end of the coach (retracted buffer end) to illustrate the collar.

My model won't have a working buffer collar but it will have working buffers.

I'll post a picture of the full brake once it is finished.

[MikeTrice]

Daft question: what stops the collar sliding around in use and dropping off?

There is an extension on the end of the collar that fits into the flange on the ram. It shows clearly on the first of the two drawings above.

Yes I saw that, but I assume it depends on the buffer head staying in close proximity to the cover. I guess the tightened screw coupling ensures this, but what stops it rotating around to the bottom of the buffer shank? Is the rebate only on the top?

Addendum: I will answer my own question. From what I can determine from the drawings (which may not include the ones published here) there are actually an extension on both ends of the collar, one fits in the rebate in the ram, the other into a corresponding rebate in the buffer head. The buffer head rebate is only present at the top of the ram effectively stopping the collar from rotating out of position.

[Dave]

Mike
here is a part view of a buffer top...you can't beat a camera with a rotatable view screen for difficult shots.

[third-rail]

hanging well out the widow while on the move to take that picture

[Dave]

Third rail

Who said I was hanging out of a window ????
If you read the post it says rotating view screen on the camera held and pointed in the general direction....which was mentioned to stop glib comments like yours.

[sirbrian]

It should be mentioned in connection with retractable buffers that the buffer shanks are rectangular in cross-section, and fit in corresponding rectangular bushings. This arrrangement prevents the buffer heads from rotating in both the extended and the retracted positions.

Sir Brian

[2512silverfox]

Are you sure? Have another look at the drawing shown earlier!

[65447]

The buffer housings and buffer shanks were circular in cross-section on LNER standard carriages; do not be confused by statements to the contrary. And anyaway, how might an obviously semi-circular saddle fit on a rectangular shank?

The 1947 General Appendix etc. provides the following:

(1) CHANGING POSITION OF MOVABLE BUFFERS

(a) To change the side buffers from the "short" to the "long" position pull the buffers out as far as they will come and place the saddles on the top of the buffer spindles, taking care that the saddle enters the grooves of the buffer head and that the lugs of the saddle are placed towards the buffer sockets.

(b) To change the side buffers from the "long" to the "short" position remove the saddles and push the buffers back as far as they will go.

(c) When not in use the saddles must be hung on the hooks provided for them on the headstocks.

[Dave]

Both Sirbrian and 65447 are correct

The buffer shank is circular then changes to square section after the headstock.
See attached photo.

[65447]

I wasn't aware that the 'tail' was square section, so thanks for that. The drawing extract does show the groove in the underside of the circular stock and the cast guide fitted at the inner end of the housing that similarly prevents rotation.