Caterpillar D6-9U Bulldozer (1952) Hydraulic Blade Control

We replaced the two turnbuckles on the 10-foot-wide bulldozer blade with two 4-inch hydraulic pistons. The pistons are controlled from the hydraulic valve up by the driver seat. The hydraulic pressure comes from a hydraulic pump being driven right off the PTO on the front of the bulldozer. This took a second to figure out, but the direction of the connections on the pistons is very important. The pistons are not run in parallel by the hydraulic lines, they are connected in series. By connecting them in series the pistons have to move in unison. For example, the left piston bottom connection (further away from the blade) has the inlet from the hydraulic pump, the left piston top connection (more towards the blade) is the outlet, the left piston top connection is connected to the right piston top and the right piston bottom returns to the hydraulic valve. As the left piston extends, the right piston contracts and the blade tilts clockwise as seen by the driver in the driver's seat. As the right piston extends, the left piston contracts and the blade tilts counterclockwise as seen by the driver in the driver's seat. This way the pistons are always being held by positive pressure by the control valve. The hydraulics were installed with the blade on the ground and the blade fairly level. The pistons allow air to bleed by the seals, so they were easy to fill with oil just by tilting the blade. Careful to recheck your hydraulic fluid level after adding any new pistons or servicing them. They are shipped empty and will fill up when used and drain your hydraulic oil reserve by a few to many quarts of hydraulic fluid depending on the volume they sweep. Also make sure to buy pistons that are strong enough to work for your blade. And also make sure they are rated for the hydraulic pressure that your pump can produce.
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[@mrneil962]

Thank you so much for making this video!

[@HarkeEstate]

You’re welcome! We were happy to do it! Let us know if there’s anything else you want to see.

[@mrneil962]

@@HarkeEstate do you happen to remember which rams you used or the length/bore? my '67 agriculture d6c with 10' toolbar blade has a dual pump so I'd use the rear implement valve. Thanks