Why return line on single acting hydraulic cylinder

[bamia]

Hello everyone,

I have a Maxon power tailgate-gravity down that came on a used truck and I noticed a broken solid hydraulic and it's dry; no drips. The tailgate goes up and down fine and after tracing the line and looking at manuals I realized it is a return line for one side of the lift. Why a return line that goes all the way to the tank and not a vent of some sort?

Thanks

 

[3DDave]

For one thing it keeps that side of the cylinder from filling with dirt, water, rust, and other contamination. For another, when the seal finally fails it won't be dumping hydraulic fluid on the ground. Finally, it is replenishing air back to the tank rather than causing the tank to inhale and exhale quite as much, which is what brings in dirt, water, and other contaminants or causes the tank to fail when the vent filter finally plugs with dirt.

It's likely that it works great and doesn't leak because of that line.

OTOH - what is a " a broken solid hydraulic" ?

 

[bamia]

Thanks Dave.

a broken solid hydraulic *line*, as in steel line.

much appreciated.