Neil, I connected the cylinders separately and off of the blade and worked them back and forth, leaving one fully extended and the other retracted. Then coupled them together and worked them, cracked the fittings to try release the air, then separated and repeated the process another time or two. I think you are referring to blade pitch. These angle blades don't allow for the blade to be pitched forward or backwards.

By driving one cylinder only and using it to drive the other one, you actually reduce the force available by half and double the speed, over a conventional system using the head end of one and the rod end of the other cylinder together. A system like this, used in steering Catamarans with twin rudders has the 'dead' circuit teed into the live circuit with valves in it to separate the two once the 'dead' side is charged with oil.

I can't seem to find a two tilt cylinder arrangement on an angle blade Cat tractor but apparently it has been done on John Deere. Maybe an investigation of their plumbing arrangement would be helpful.

The JD tilt system pictured in OM's post is plumbed so that the rod end of the left cylinder is connected to the head end of the rh tilt cylinder. the rod end of the rh cylinder is connected to the head end of the left cylinder.

following pascals law, one cylinder will not move before the other in this arrangement.

the newer (2004 an up) leibher/jd large crawlers with a straight bulldozer blade had an electric over hydraulic switching valve that would allow you to tilt the blade, but you could also press a button and move the same lever that controls the tilt and it would adjust the pitch of blade.

I once looked after a fleet of D6D's with tilt cylinders on angle blades, meaning tilting the blade side to side, they did not tip the blade backwards and forwards, they were connected head end one side to rod end the other, if both rams were disconnected and one had a new set of seals, the other would travel full stroke before the resealed ram would move. this is the correct way to pipe up tilt rams.
By using oil from one ram to drive the other, the pumped oil is only going into one ram, so hydraulic effort is reduced by half as only one ram is being used and the speed is being doubled over the conventional twin ram circuit. Conversely, the effect of external force on the blade is being doubled back through the hydraulic circuit because only one cylinder is trying to resist the external force.

I have used the machine for a couple of days now and am happy with how it has worked out.
I realize that I have only the force of one cylinder working but it is enough for the application.
I have seen a few angle blades fitted with a single cylinder, and either the stroke is too short to allow for much tilt or else the center pivot has become butchered. If they had a ball setup to allow the center pivot to move on three axes I believe it wouldn't be so much of a problem.

Glum--i am a little confused now--looking at your schematic when you pressurize p1 on the piston end it pushes that rod out---the oil in the rod end is then pushed to the rod end of the other cylinder pushing that rod in---it seems to me you have force pushing one end of the blade up and force pushing the other end down---as long as there is provision to relieve the pressure on p2---and then vice-versa for opposite tilt.

Dan, my terminology is probably a little off. P1 and 2 are just the two pressure lines coming from the control valve. Both will dump back to the tank.

dpendzic - I'm far from an expert, but I believe what glum is referring to is force, not movement. The way he has them plumbed, both cylinders will move, one in and one out, whenever hydraulic flow is applied by movement of the lever. Move the lever one way and one will go in and the other out, move it the other way and the first one will go out and the second one in.

I believe what glum is referring to with his comment ". . . I only have the force of one cylinder . . ." is the effort applied by the system. If the cylinders were plumbed more conventionally, with a separate and isolated connection to the system for each cylinder, the two collectively would exert twice the force as they do the way he plumbed them. In other words if, say, 1,000 PSI is applied to the system the way he has it plumbed, the two rams will exert a certain push on the corners of the blade, one in and one out. Let's say that force could be measured and the collective value was 750 PSI, for example.

If that's the case, then if you replumbed the exact same system so that each cylinder were connected separately to the system and applied the same 1,000 PSI of hydraulic pressure, your collective value of force applied to the blade corners would then be 1,500 PSI.

This happens because the way Glum has the cylinders plumbed, the pressure of the hydraulic system is acting on only one face of each piston, cutting the applied force in half. If the system is applying force to both sides of both pistons, the applied pressure is twice as high.

Glum points out that there is plenty of force with the available hydraulic system to hold the blade against any pressure the tractor can apply, so the diminished hydraulic force doesn't matter in this application.

I hope I've got that right.

Pete.

You got it right Pete, just like I said twice before, it will work, the biggest problem is filling he 'dead' side of the circuit with oil, this can be done by fitting a tee an shut-off valve into the live side to feed and bleed the system. This will also make the blade more solid, air compresses remember. an air lock could even cause an explosion if it was compressed enough.