Testing out the hydraulic flow limiters

When we finished building the excavator a while back, it worked fine but seemed to move a bit too quickly on some of the directions. At best, I had to be very careful to barely open the valves, but at worst it was dangerous to anyone or anything nearby.

So I read up on hydraulic flow limiters which can reduce the flow rate of the hydraulics without reducing the force. Having more familiarity with electronics than fluid dynamics, I think of it like an electronic resistor, which reduces current (flow rate) while not affecting voltage (pressure) at low current.

Here are some close-up pictures of the flow limiters installed on the left and right side of the control valves:

Front

Back

(The bottom picture is not so good, but the ground was muddy on the other side so I was too lazy to go around. Sorry.)

Each flow limiter has a brass screw to adjust the flow rate. You can see from the top picture that they come in pairs, one for each direction of the hydraulics. We have one pair for the side-to-side motion of the arm, and another for the “shoulder”.

As for the results…
They seem to work quite well for the side-to-side and the up motion of the shoulder. The down motion seems unaffected, though. At first I thought this might be due to the force of gravity somehow. But when I tested it pushing down against the ground (to lift the front of the excavator off the ground), it didn’t seem to limit speed then either. I am now suspecting that one is defective. The next test will be to switch it with the other one and see if the problem occurs on the upward instead of the downward motion.

In any event, even the 3 out of 4 improvement feels like it makes handling the machine much easier.