Excavator boom swings and drops too fast

   / Excavator boom swings and drops too fast #11  
Have no idea as I have a box of them on the shelf I bought years ago.
 
   / Excavator boom swings and drops too fast #13  
That works too and I've done that as well, so long as the ID of the cent will fit in the fitting. Way back when we used to put dimes in the front air lines on big trucks to disable the front brakes. That was before ABS came along. Front brakes on big trucks were an invitation for suicide on a wet or snowy road.

Nice thing about 'rolling your own' is you can start with a very small hole and work up for flow.
 
   / Excavator boom swings and drops too fast
  • Thread Starter
#15  
   / Excavator boom swings and drops too fast
  • Thread Starter
#16  
Because I'm inherently cheap, I make my own restrictors out of appropriate sized copper blanks and drill my own restrictor holes in them the copper acts as a seal too. You can use brass as well but copper is better.
Where did you get the copper blanks? What are they called?
 
   / Excavator boom swings and drops too fast #17  
Is it possible that someone replaced the pump, and substituted a larger pump?

If this machine is a simple open center hydraulic system, those restrictors can shorten the life of the pump.
On open center systems, when the hydraulics encounter a restriction, the oil must open the relief valve.

When the relief valve opens, ALL of that pump horsepower is converted to heat.

Too much heat,, something fails.

Can the engine throttle be reduced to resolve the hydraulics speed problem?
 
   / Excavator boom swings and drops too fast #18  
penny.jpg
 
   / Excavator boom swings and drops too fast #19  
The adjustable flow restrictor is a good option, you can have free flow one direction, restricted flow the other. They don’t have to be at the valve, you can install them at the cylinder ports or in-line if needed.

This is what I did on my Branson backhoe. I put them on the boom cylinder, set to restrict flow out of each port of the cylinder. It pretty much eliminated the up and down jerkiness. They're set to restrict the outflow on the theory that restricting inflow might cause cavitation. I'm not sure it would, or if it'd make a significant difference.

Between the piston end and rod end of the cylinder moving different amounts of fluid and gravity only working in one direction, the two restrictors ended up with different settings to get things just right. That's why I went with two instead of one.
 
   / Excavator boom swings and drops too fast
  • Thread Starter
#20  
Is it possible that someone replaced the pump, and substituted a larger pump?

If this machine is a simple open center hydraulic system, those restrictors can shorten the life of the pump.
On open center systems, when the hydraulics encounter a restriction, the oil must open the relief valve.

When the relief valve opens, ALL of that pump horsepower is converted to heat.

Too much heat,, something fails.

Can the engine throttle be reduced to resolve the hydraulics speed problem?
The pump is original based on the parts diagram from Case. There is a HUGE oil cooler on this machine and the old hydraulic valve body had three orifices in the ports, probably to eliminate exactly what is happening.
 

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