Blockoff plate on C hydraulics

What does the plate that goes between the hydraulic lines and the rocker box on a C Farmall consist of? Is it just a place to hook hydraulic lines or is there some sort of valving in there. If its just a block, why couldn't I use the holes in the plate on the end of the hydraulic lines to hook up the external cylinders? Thanks for any info Bernie Steffen

First off I'm assuming that you're talking about an add on by-pass block rather than the valve used on the Super C etc to control the fast hitch cylinder.

The plate I believe you are referring to does not contain any valving and does provide a place to hook at least one hose into. HOWEVER that's not all it does. It is really a diverter plate.

In the factory setup for a C, the hydraulic fluid flows from the touch control to the pump, and from the pump back to the touch control. No pressure is developed until the touch control is operated and then it only develops what is required.

When you add in the bypass block instead of the oil returning directly from the pump to the touch control it now passes through your added OPEN CENTER hydraulic valve. This means that you new valve is upsteam of the touch control and when you operate it pressure will be developed (pressure is simply resistance to flow) until it is sufficient to operate the funtion you have selected.

If you didn't have the bypass block and you operated your hydraulic valve nothing would happen as no pressure would be developed because the fluid would take the path of least resistance and return directly to the touch control.

Hope that was helpful,

Sam

Sam That was exactly what I was lookin for. Guess I have to buy a blockoff plate. If I knew how it was configured I probably could make one. Oh well its ony 50 dollars. Thanks for the info Bernie Steffen

They are simple enough to make (says he who was considering buying one himself if you have the gear. The basic layout is as follows (wish I had a pic but maybe you'll follow).

I'll leave you to determine the actual size of your block but it needs to be larger on the 'flat' sides than the gasket between the pipes and the touch control (probably obvious). The thickness is determined by the size of the pipe fittings you'll use (more on that later) but you want it as thin as possible (to minimise the distortion of the steel pipes) while maintaining adequate strength. You then need 3? holes for the mounting bolts to pass through.

Now the really important bit.

If you closely observe the two steel lines you'll see one slightly larger than the other. This is the return line, drill your bypass block straight through at this point (simple enough). Now for the other line. In line with the pressure line (the smaller of the two) and starting from what will become the touch control side of the block drill 1/2-3/4 of the way through your block. Now drill in from the nearest (or most convenient for later hookup) edge to meet up with your last hole. Then tap for the hydraulic fitting of your choice and install.

The supply line for your open center valve should be plumbed into the pipe plug in line with the pressure line on the original manifold (at the end of the steel lines) and the return line is plumbed into the block. You may wish to consider adding a pressure relief valve as your add on system is upstream of the one already in the touch control and so it would be possible to 'dead head' the pump (1100-1500psi would be suitable). Hope some of that made sense, Sam

I made my own at work. For $50, Buy it.

Yes, the bypass blocks are a "fun" machining project. There's a guy on ebay who sells them for $40 plus shipping. Nice work. I've got one each of his Super C and Cub plates.