few experts says it is important to mount hydraulic reservoir at higher lavel then pump

in an open loop,like an backhoe loader is it really important to place pump below the tank .

most backhoe and front end loaders have ven or gear pumps.

is it possible in any case to mount reservoir slightly below the pump. i have seen some backhoe loaders have this type of tanks.
i have photos.are they fitted with some spcial arrengment.

please tell me the truth.

You can mount the pump(hydraulic/positive displacement) above the reservoir. I guess the rule of thumb is not more than 3 feet above the fluid level. I don't want to calculate to show how , but others can do if given enough data. Just try to avoid too much bend on inlet and the inlet pipe must not be reduced(same inlet port pipe size recommended by manufactures).

Tony,
"please tell me the truth"-So Help Me God !!!.
The location of an oil reservoir is not the issue.
The Vaccum on Pump Suction Port should be according the pump manufacturer
recomemmdation. Cavitation in suction line causes the creation of free air
that when passing to the pressure port creats "small explosions" called
"Diesel Effects" that causes erosion in the pump preesue chamber that will
damage the pump.
I recommed always to try to keep positive pressure on suction port no matter
the location , distance , diameter , bends etc'. The meaning is , you must
calculate pressure drops , positive or negative hight , flow conditions
(oil viscosity , temperatute Reynolds number (keep Laminar Flow) and so on.
It is not simple and never try to use Thumb Estimation based on oil speed.