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Since I'm new to Blender (I made the model and rigging with gMax), I find myself stuck trying to set up a linkage for the reverser of my steam locomotive. I was finally able to set the pivot point for the lifting arm using the iv constraint (reverser 1a).

Reverser 1a

When attempting the function the arm moved correctly but the bones disconnected and failed to raise the reverser arm. None of the constraints could remedy this (reverser 1b).

reverser 1b

Further attempts kept the bones together.

reverser 2a

However I was never able to keep the last bone attached to the linkage.

reverser 2b

Any help would be greatly appreciated. Have a great day. TOM

Addendum: I have been able to answer most of my questions through a lot of trial and error. I am trying to model this steam locomotive for use in TRAINZ.

lok

A short video of my progress can be seen on Youtube.

I was able to do the linkage with an armature starting at the reverser lever. Using IK constraints with limited chain length I could connect to various objects. Everything works great when running forward:

forwards

The problem is when shifting into reverse since the radius and valve rods are location constrained to the Y-axis of the expansion links pivot point, the motion is no longer correct.

reverse

I have tried everything I could think of, including the clamp to constraint, without success. I would be grateful for any ideas. Have a great day. TOM

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  • $\begingroup$ Do you specifically need bones for this? Have you tried with a constraints only solution? Might be easier to achieve what you want. See related blender.stackexchange.com/questions/78170/… $\endgroup$
    – Duarte Farrajota Ramos ♦
    Commented Jul 12, 2017 at 23:48
  • $\begingroup$ Sorry. Just got the notification of your reply. Thanks for the link. I tried using rigid body hinges but wasn't successful. Thanks again. TOM $\endgroup$
    – Thomas Frede
    Commented Jul 14, 2017 at 2:16
  • $\begingroup$ Here one of my attempts. I believe I set up the hinge correctly. The L-shaped arm is child of the lever base and can rotate on the x-axis which is the z-axis for the hinge. (image 1). $\endgroup$
    – Thomas Frede
    Commented Jul 15, 2017 at 6:41
  • $\begingroup$ Here one of my attempts. I believe I set up the hinge correctly. The L-shaped arm is child of the lever base and can rotate on the x-axis which is the z-axis for the hinge. (image 1) On the second picture you see that rotation of the l-shaped arm breaks apart the objects instead of bending at the hinge. I may try bones again. TOM P.S. Could not add pictures. control G failed to work. $\endgroup$
    – Thomas Frede
    Commented Jul 15, 2017 at 6:56
  • $\begingroup$ Could you include the name of the locomotive? $\endgroup$
    – Haunt_House
    Commented Mar 13, 2018 at 16:43

1 Answer 1

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I've been at it over a month. I have a 99% solution. The pictures show what I have done in Forward and Backward gear. The solution isn't perfect because the travel between gears is on a circular route. I posted a video on Youtube. The first 30 seconds are still photos and then the action starts. If anyone has an idea how to make a straight route let me know. Thanks. Have a great day. TOM

https://youtu.be/L5k6kLqcca4

FORWARD

BACKWARD

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