Hey Terry, I apologize for jumping to conclusions after reading your first post, I should have known better, but it sounded like you were talking about some kind of reduction gear system.
I should also give you another 'sorry' for not reading posts that have been made while I'm typing a reply, it would save a lot of time if I checked what had just been said before I hit post myself; this is a bad habit I've got to get rid of.
Now, for this last one, I'm not trying to be funny or clever here, I actually thought this; look, I know that you're mechanically inclined and that you are well versed when it comes to this type of discussion, so I couldn't figure out what you were talking about, you had even originally supplied a drawing of this type of carriage to Zulu before he began this build, so you had to know how the wheels worked. Well, my brilliant answer for your misunderstanding was that the reason for it could be due to some potent meds that you were prescribed. I'm sorry, buddy, that is definitely
my mistake! Terry, maybe it would do me some good if I took something to clear the cobwebs out of my own attic.
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I have seen demonstrations where handspikes were used on other mounts to raise the rear of the carriage off the chassis. Perhaps this was the purpose of the handspikes in the photo?"
I agree; there was a good YT vid that had reenactors at a (I think) California fort manning a sliding carriage, and it showed them using the handspikes to lever the carriage forward from the rear. I've checked for this vid a few times now, and unfortunately I think its gone.