Transport valve settings

On a D-17 ser.3---To plow with 2 bottom SC plow,Do I turn knob out or in? I have misplaced my owners manual and the decal on the valve is worn off. Thanks for any help!!!  And what is the purpose of the transport valve? 

The purpose of the transport valve is to allow the use of the traction booster weight transfer system when pulling semi mounted snap coupler implements with their own transport wheels.  The obvious implements this would apply to are plows with a trailing wheel and ram and discs with transport wheels and a ram.  The transport valve prevents the flow of hydraulic oil to the implement's ram when the system is operating at the lower pressures at which the traction booster operates.  It only allows oil to flow to the internal ram so that weight is transferred via the lift arms to the rear wheels of the tractor.  When you move the hydraulic lever to the lift position, the lift arms lift fully, and then pressure rises sufficiently in the hydraulic system to force oil through the transport valve to the remote cylinder, thus raising the implement.  Working depth of the implement would be controlled by the adjustments on the implement itself.  The transport valve does not affect the working depth of the implement.
For your fully mounted two bottom plow, the transport valve is unnecessary. 
I can't remember off the top of my head whether the valve control needs to be turned clockwise or counter clockwise for the valve to function.  Turned in one direction, it's just like the valve is not even there, which is what you want for fully mounted implements.  Turned fully in the other direction, it will function as I described above.  You can check it as follows.  Raise the plow fully and place the hydraulic lever in the hold position.  Then, turn the transport valve control fully in one direction, then turn it fully in the other direction.  When adjusted to function for the semi mounted implements, the lift arms will leak down.  When adjusted the way you want it for your fully mounted plow, it will hold.  The valve control should be turned fully in one direction or the other during use.