Holmatro HGC S Serie Manual De Instrucciones página 37

3 Description
3.1 Equipment
The cylinder can be either a single-acting or double-acting hydraulic unit. This depends on the
construction of the return mechanism of the plunger.
• Gravity return: the plunger is returned by the weight of a load or of the plunger itself (Fig. 2).
• Spring return: the plunger is returned by an integral spring in the plunger (Fig. 3).
• Hydraulic return: the plunger is returned by the double-acting hydraulic system (Fig. 4).
NOTICE
On double-acting hydraulic return cylinders, the hydraulic system in the cylinder is provided
with a safety valve. This safety valve prevents excessive pressure in the cylinder if the
return line to the pump is blocked by venting oil outward.
WARNING
To prevent excessive pressure always:
• Connect both hoses
• Limit pump flow , see section 3.3.
If not or bad connected, or too much pump flow, the safety valve will vent oil outward.
WARNING
Eye bolts are only for hoisting this cilynder. Do not use these for other objects.
• Air pressure return: a pressurized space is present above the plunger (Fig. 5). When the return
travel movement of the plunger slows down, the plunger is returned by the internal air pressure
(6 bar in lowest position).
Gravity return, spring return, and air pressure return cylinders are fitted with one coupler. Hydraulic
return cylinders are fitted with two couplers.
HYDRAULIC CYLINDERS 916.000.851_007
EN
37