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All Springer/NP/PCP Air Gun Discussion General > Engineering- Research & Development

Crosman 1400 valve improvement

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jackssmirkingrevenge:
For those unfamiliar with the model, unlike more conventional rifles the Crosman 1400 has a "blow open" valve that is held shut by the trigger assembly and opened by the chamber pressure.

Here is the "valve train" from a used example I picked up last year:



1) and 4) is the chamber body, with the check valve 2) being held shut by spring 3).  Air from the pump comes from the left of the image.

5) is a cup shaped piston that slips over the nipple on the right of chamber 4) keeping it sealed as long as the trigger keeps part 9) in place, locking it through rod 7).

When the trigger is pulled, 5) is free to move to the left of the image through cylinder 6), allowing the chamber to dump through the transfer port into the barrel.

Parts diagram for completeness' sake:



I've floated some ideas elsewhere on what can be done to improve the valve system and wanted to put some thoughts to pixels as to a practical way of going about it:



The idea is to replace the piston with a slightly unbalanced spool that would allow for much greater flow than the original porting (which at 1/8" is a mere 32% of the 0.22" barrel cross-sectional area) without adding too much stress to the trigger group.  At 1000 psi, the standard setup is pushing on the trigger with 28 lbs of force.  With spool end diameters of say 0.30" and 0.29", that force is reduced to a mere 5 lbs for the same pressure.

The air from the pump would flow through the endcap thread and the endcap o-ring would be floating to act as a check valve.

The spool apparatus cluttering the chamber will result in a smaller available volume of air, but I'm confident that the increased flow as well as the fact that much greater pressures can be reached without  making the trigger harder to press will result in a considerable net gain in performance.

AmBraCol:
Very interesting.  I'd never seen the innards of one before.  Is this something you're in the process of building?

jackssmirkingrevenge:

--- Quote from: AmBraCol on April 30, 2019, 09:38:54 AM ---Is this something you're in the process of building?
--- End quote ---

Right now all I have is a disassembled rifle, the intention is to rebuild it with an improved valve once I refine the design.

AmBraCol:
Sweet!  I look forward to following the build.   ;D

YEMX:
I was just thinking about something very similar a few days ago- kind of marrying the easy to open nature of the Cothran or SS valve with a 1400 to get higher velocities without sacrificing the trigger pull for the higher pressure...  Maybe even improving the trigger pull.

I'll be following with great interest!!

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