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3D model: Baikal MP-46M single stroke pump mechanism: piston linkages; not valve

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subscriber:
EDIT:  If you are in a hurry to see the objective motion study , click link below to take you directly there:https://www.gatewaytoairguns.org/GTA/index.php?topic=153475.msg155689447#msg155689447


A few days ago I had my 46M apart to increase its compression (velocity); by adjusting the piston "TDC". 

Then, I took a bunch of pictures and measurements of the cocking linkages.   While I tried to accurately capture all the functional dimensions, I did take some licence with the aspects that are somewhat arbitrary; such as the cocking handle shape.   

In order to understand the dynamics of this brilliant mechanism, I thought I would "quickly" model it in Solidworks.  About two days into it, and this is what I have - below.

For clarity, parts that would clutter the design were left out.  In fact, I simplified (?) the design, and eliminated the need for two of the parts - explained further down.   

Another EDIT:  The "guide" parts I left out of the design, do help to stabilize the compression tube, where it is cut into a "U" all the way to the front.  The barrel band clamps the tube down onto the internal "guides", and so improves the system integrity.  Thinking another way; the parts would not exist, if they had no value.  However, they are not critical to enable our understanding of the linkage dynamics...


Baikal IZH MP-46M SSP pistol:

subscriber:
Opening the charging handle to draw in a full charge of air.

Note that the pump handle makes contact at its outer surface against the forward intermediate connecting rod (not the one hinged at the piston).  In this phase of operation, the friction reducing rollers are idle and are not in contact with the rear side of the pump handle.

In my model, both the opening and closing surfaces of the pump handle are in contact when the full opening stroke is reached.  The actual piston has two extra parts that the hinge pins pass through that regulate the full open handle position.  These parts also determine the degree of over-center of the piston connecting rod. 

I have taken licence by simplifying the design; and "throwing out" the two extra parts:  There is a U-notch in the forward intermediate link that acts as a positive stop to determine the connecting rod over-center resting state.

subscriber:
Closing the pump handle to pressurize the valve.

Image number 12 in the previous post is the actual starting point for the charging (closing) stroke.  It is also the end of the opening stroke.  The actual pistol has a little travel between these states.  It also has a vent hole in the top of the cylinder that determines the 100 mm effective stroke length...

Note that the contact has shifted to the friction reducing rollers at the hinge point of the intermediate slider linkage...

Also, not that the piston connecting rod goes over center by one degree, or about 2 mm at the anti-friction roller surfaces.

subscriber:
Actual forward intermediate connecting rod, showing friction reducing rollers. 

Note piston dangling off to lower left, via actual connecting rod.  Two connecting rods are hinged together with a rivet; that also captures anti-friction rollers.

rsterne:
If I understand correctly how this works.... a simple scissors pumping mechanism like a Crosman 13XX would have the forward-most link rod extended past where the rear link lever connects to it as the pump arm.... This mechanism uses a changing leverage system, via the roller, to increase the mechanical advantage during the latter stages of the stroke....

Bob

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