Mechanical Brake Tracks & Rolling Pins

[H. L. Chauvin]

Hi Marco,

As Bob Johnson indicated above what some may think a mystery, front & rear mechanical brakes can be explained as:

1. The front & rear drums can be turned to be fairly accurately concentric with the axle.

2. If the shoes were not re-arched, all of the brake bands can be ground to be fairly accurately concentric with the axle. (Remember that the short distance from the outer surface of the brake bands to the tops of the rivets is critical "when", not "if" the brake bands wear).

3. The front & rear brake adjustment wedges (A2041) were & most likely are still are accurately positioned in a fixed position in the front & rear backing plates & cannot move.

4. The front brake adjustment shafts (A2042), & the rear brake cams, (A2230) can be fairly guaranteed to be of equal lengths if provided new; hence, maintaining a fairly accurate concentric position of the ends of the adjacent brake bands correctly positioned in the concentric drums.

5. The front brake operating wedges, if new, can guarantee that adjacent ends of the shoes remain fairly accurately concentric to the drum.

6. The front brake front to back positioning of the brake shoes can be equalized if one uses front brake floater (A2051F), which allows the brake shoes to be equalize as that of the rear shoes with the sliding cam.

7. Next, providing new roller pins, (A2045) & new adjusting shaft pins (A2740) in serviceable brake shoes can help achieve brake bands that are again fairly accurately concentric with concentric drums;

8. After achieving items 1. through 7. above, & possibly other tweeks, one can achieve very close to concentric brake bands that are fairly accurately concentric with concentric brake drums.

9. Then, here comes the Devil: (well noted in your reply no, 4 above): The new or "used" metal tracks, possibly not accurately positioned & riveted in "used" backing plates. (Mr. Les Andrews & others mention tweeking same up or down with a wrench)

10. Many tracks have been re-worked in every manner imagineable whereby the flat surfaces of the tracks are perhaps misaligned at an angle, or are installed while not having the proper dimension from the axle to provide concentric positioning of the brake bands in the concentric brake drums.

11. "If" the tracks were at any time improperly installed with re-worked rivet holes etc., the above flat surfaced pins accompanied with possible re-working of tracks could possible help to properly position the brake bands in a more concentric position.

12. These flat surfaces of the flat headrd pins, if lubricated, could extend the life of the track wear. As the tracks wear, as many do with round pins, the concentric bands begin to move slightly towards the tracks.

13. Realizing that flat headed pins may not be for everyone, & also that flat headed pins can be home made, do you know of someone who sells flat headed pins with incremental dimensions similar to those indicated in your reply no. 4.

And again, most sincere thanks for all that you do.