Not Orange... but FooBert started this....any Heavy Machine Operators out there??

GeoHorn

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Equipment
M4700DT, LA1002FEL, Ferguson5-8B Compactor-Roller, 10KDumpTrailer, RTV-X900
May 18, 2018
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Texas
In another thread, Foobert gave an excellent summary of how an HST system operates. This has provoked me to see if anyone can offer insight to another HST powered machine which is “yellow”.


I have a ‘87 Ferguson 5-8B Compactor/Roller which was surplus-ed off by the Tx Dept of Trans (highway dept) probably around 2008 when it was 20 yrs old and picked up by some company down in San Antonio, subsequently sold off to a smaller company who sold it to me. No records exist on this thing and it’s been a learning experience because the hydraulic opertional-recommendations are not fully explained. (THANKS FOOBERT for the HST summary.)
There’s a “water faucet/valve” type of by-pass which no one (including the phone-answerer up at Ferguson, who still mfr’s this same machine with minor changes of engine, etc.)... no good explanation of what to do with this valve. If I “close” off the valve when idling-but-stationary... a progressively-louder HST-whine occurs.... so I stopped closing that valve. If if close it partially the “pedal” (a lever actually) becomes Much more authoritative and loads the engine much sooner.
If I keep it almost fully “open” the go-lever is less sensitive...

The manual I’ve found for this thing on Ebarf is for the same model but different engine (no problem there) but it also does not provide good guidance on what to do with this valve. The manual says to “close” that valve, but doing so causes the system to “shriek” so loudly ...it CAN’T be good..... So I’m operating it at a mid-point and seeming to have no particular trouble.

Any heavy equipment operators familiar with this sort of machine?
 

ruger1980

Active member

Equipment
L4310 w/La682, L225
Oct 25, 2020
395
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CNY
Do you have the hydraulic schematic for the machine? Most likely Eaton or Sundstrand hydrostatic drive but who knows what the OEM could have done to change the operation. Pics may help as well
 

foobert

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BX2380
Mar 25, 2021
112
111
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Washington
Based on your empirical observations, perhaps this system has a constant displacement pump and your valve in question is modulating the bypass fraction. You could test this by fully opening the valve, set the direction lever to full speed, and observe if there's any increase in speed after closing the "faucet" valve?

Edit: If my suspicion is correct, it shouldn't make a terrible whine while moving, but, you'll want to open it back up some before returning the direction lever to "neutral".

Also, thanks for the kind words -- glad someone found it interesting (y)
 
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