oldnslo
Super Member
If the pump is drawing air it would be noisy and affect all of the functions not just the dump.
Floppy bucket is caused by the cylinder extending faster than the pump can supply. This creates a vacuum in the cylinder which creates an air pocket. This is also called an overrunning load. Holding the control valve until cylinder is fully pressurized eliminates the vacuum and greatly reduces the floppy bucket.
Different ways to reduce or eliminate this occurrence.
Regenerative system: valve connects both the rod end and cap end of the cylinder to pressure so fluid exiting the rod end is forced into cap end pump only makes up the volume difference of the rod. Since both ends of cylinder are at similar pressure very little chance of drawing a vacuum
Orifice or restrictions in rod end hose. Works ok but requires some fine tuning to get control under most conditions. Has very limited success if trying to feather control especially with load on forks.
Counterbalance valve: these are designed to prevent overrunning loads from running away. This style valve keeps a positive pressure in the rod end of the cylinder. These Work well under all conditions but are the most expensive solution and potentially challenging to install on existing FEL circuit.
Floppy bucket is caused by the cylinder extending faster than the pump can supply. This creates a vacuum in the cylinder which creates an air pocket. This is also called an overrunning load. Holding the control valve until cylinder is fully pressurized eliminates the vacuum and greatly reduces the floppy bucket.
Different ways to reduce or eliminate this occurrence.
Regenerative system: valve connects both the rod end and cap end of the cylinder to pressure so fluid exiting the rod end is forced into cap end pump only makes up the volume difference of the rod. Since both ends of cylinder are at similar pressure very little chance of drawing a vacuum
Orifice or restrictions in rod end hose. Works ok but requires some fine tuning to get control under most conditions. Has very limited success if trying to feather control especially with load on forks.
Counterbalance valve: these are designed to prevent overrunning loads from running away. This style valve keeps a positive pressure in the rod end of the cylinder. These Work well under all conditions but are the most expensive solution and potentially challenging to install on existing FEL circuit.