1980's 60' boom lift hyd. control troubleshooting - same as tractor hydraulics?

dfkrug · Oct 18, 2013

oldryder said:
I do have a set of elec and hyd prints but the hyd prints are mostly "greek" to me.

Do you have the full service manual from Terex? Just a quick look at the Marklift CH60 shows a very extensive
set of hyd and electrical schematics and component ID diagrams (232 pages!). I know that is a 1990s unit, newer
than yours. Genie customer service was very helpful to me when I was rebuilding an old AWP, and I got complete
service PDFs from them for free. Their website has an email contact page.

I would like to rent a Genie S65 some day.

oldryder · Oct 18, 2013

I do have a manual with schematics. However, while I can read the elec print I was looking for help on understanding the hydraulics since my problem (good progressive speed control in REV and immediate full speed motion in FWD.) could be in the elec controls or a hyd. problem.

Someone that can read the hyd prints might be able to confirm that correct proportional motion in one direction means it can't be hyd.

BukitCase · Oct 18, 2013

Sorry, print is kinda fuzzy and I wasn't looking for motors at the time - guess 11 tons and 4wd might complicate things a bit :ashamed:

Print looks to me like you have check valves bypassing the speed control valves one way, but I'm not sure what the valve at far left is, label isn't in the pic.

The only thing that's common to lifts I've run is that they won't let you go fast if the boom is up or extended - don't remember any that cared whether you went forward or backward. That would explain what seems to be happening though :confused2:

Here are (hopefully) a couple of helpful links on hydraulic prints, note the check valve symbol in the first one

Schematic Symbols Chart (Design Hydraulic and Pneumatic circuits/diagrams)

ISO Hydraulic Schematic Symbols - Engineers Edge

HTH... Steve