Heli CYPD25:
mast lowering problem

5000lbs lift truck 3 stage mast. Free lift/carriage is lowering at twice the speed of mast channels/secondary cylinders.

Mast raises normal and has no problem lifting a load. When lowering from any height above free lift. The free lift will lower 1st and faster then the channels. If you release the handle to the neutral position the channels will continue lower and push Freelift up until the pressure is equalized. I have lubed the channels, have taken apart Freelift cylinder and resealed. Secondary lift cylinders have clear vent hoses at the top and there is no oil in the vents. At a loose as to what is causing this problem. I asked the customer if this problem just started with no warning or if the problem came on slowly....replied that problem just started out of the blue. I also chained up the carriage and lowered mast to see if the speed of the channels increased...only slightly faster.
Removed and disassembled a flow control valve that is in-line with supply line. Saw no obvious problems with valve.
  • Posted 25 Sep 2013 08:33
  • Discussion started by hellcat
  • Florida, United States
Showing items 1 - 1 of 1 results.
Sounds to me like there is a small "cushioning" valve in the bottom of the free-lift cylinder ram that has either gone bad or is leaking past or fallen out. You will need to pull the ram all the way out to see and change it. it is about as big around as your pinkey and about 1/2 as long and right in the bottom center of the lift cylinder ram.
  • Posted 25 Sep 2013 20:07
  • Reply by edward_t
  • South Carolina, United States
"it's not rocket surgery"

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