My 685 has Aux hydraulics. Is it supposed to be a self centering valve spool? My lever is stiff and I'm not sure what way is off or on. No rpm change like its setting a relief off if i move it either. I just want to make sure its "off"
You're right! The 685, along with most of the Hy Hoe line (not the 6000), usually came with an auxiliary hydraulic circuit (minus the plumbing) available to plumb in to. It was in the swing valve circuit. There are 3 plungers in the swing valve. The outer plunger is for the swing circuit to the swing motor. The inner plunger is for the boom assist. The center plunger is the one that is available, to be used (tapped into) for auxiliary functions (hammer, compactor...). If not used, it may stick. Cable controls tend to stick/seize up, more than mechanical. If not used, just disconnect it. Check your linkage for uneven wear points, like on air brakes.
Also, if you don't like the drift of the free swing & you're not using the aux. circuit, swap the plungers. the swing plunger (unless it's been changed) will be drilled at a right angle to the plunger to help to cushion the swing & the aux. plunger will be solid.
Unless the spring at the rear of the plunger is broken, or there is a burr or corrosion in the plunger bore or the plunger itself, the sticking is probably in the linkage or cable (they used both). The way the plunger is designed,
it is self centering, by virtue of the spring. When you let go of the control, no oil should flow through it. You should notice no bogging down or change in rpm.
You may notice a 'sticking' problem with the boom assist, as few people ever used this function & the control linkage tended to seize up, stick, below the plate under your foot. The way the boom assist works, is, when you pull or push the control for the boom, if you want more flow you go right or left with it (up or down for boom), you would divert 1/2 of the flow from the swing circuit to the boom cylinders.
Really increases the lift speed when lifting out of a deep hole, or clearing the edge of a ditch.
Standard also was a regenerating valve to help cut the lag time on the dipper, to keep the stick moving when it is at 90 degrees to the boom. The valve was mounted behind the dipper cylinder on top of the boom. It channels (re-uses) the return oil from the cylinder (in or out) to the chosen direction of flow. Without it, or if it is worn, the dipper will slow right down, or even pause, for a moment. Hy Hoe called it a 'Hy Hoe exclusive'. When I bought my Case machines I asked them if they could install this feature along with the extra valve on my new machine. They wanted $20,000.00 extra!! So it didn't happen.
The new hoes get past this lag by decreasing the size of the cylinder barrel (the rod is usually the same size, or it will bend). Reduced area to fill with oil = faster speed = less power pushing away. You still have good breakout force, as they also increase the p.s.i. but it will stall when you push the stick away, against a stump or pile of dirt.
Hope that's not too much info.
TT beside the 685 B
