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I'm wondering how this valve operates. What I don't understand is how the valve operates with only one oil inlet. Does the rear pump simply OVERWHELM the inner spring and the first exhaust port thus moving the valve to engage the outer spring? At this position fluid is routed to the front pump relief valve which idles the front pump. Pressure greater than 93 PSIG exits the front pump exhaust port achieving regulation at 93. What is the purpose of the first annular groove?

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There is a good description on how the valve works starting on page 16 in the original Ultramatic training manual.packardinfo.com/xoops/html/downloads/UltramaticTrainingManual.pdf

I've read that multiple times. I read it again. I believe the valve is shown in its initial position which allows oil to the front pump relief valve. I would have thought that the first exhaust port and the inner spring would have regulated the pressure to the converter inlet valve. I guess the rear pump pressure is so much greater than this regulated front pump pressure such as to overwhelm the first exhaust port and continue to move the valve inward. It makes sense that the flow rate of a liquid through an aperture would have a point of non-linearity verses pressure. I believe the front pump is regulated at 85 and the rear at 93, pretty close. Also, the purpose of the first annular groove is not explained.