With the quick-dumping hydraulic coupling, you may encounter the problem of DUMPING WHILE UNDER LOAD or EXCESSIVE SLIPPAGE. Either of these malfunctions may be caused by plugging of the pressure relief nozzles located in the periphery of the secondary (piston-type) rotors. These nozzles consist of drilled allen setscrews, mounted in the secondary rotor at the ends of the radial tubes that feed air or oil to the dumping valves. The nozzles permit the feeder tubes to drain when the air or oil supply valve is closed, thus allowing the dumping valve to return to the closed position. The nozzles also permit the draining of any oil that has leaked past the control valve when shut.

There are also leak-off nozzles in the periphery of the secondary rotor at the base of the dumping valves. The leak-off nozzles serve as flushing exits for the valves and allow a continual flow of oil past the inlet port of the dumping valves. The oil washes away any particles of foreign matter that may collect as a result of the centrifugal force acting on the oil.

The best way to prevent a hydraulic coupling from dumping while under load is to keep the oil system free from foreign matter. Gasket compound and shreds of copper from oil tube packings often cause trouble. Every possible precaution must be taken to keep the oil system clean from foreign material. To aid in this, the system has a strainer that effectively catches, or traps, most of the foreign matter that may reach the nozzles. All nozzles must be blown out during each overhaul.

If nozzles become clogged during operation, it is possible to clear them by operating the dumping control several times. This action may blow the obstruction through the nozzle opening. If this method fails, it will be necessary for you to secure the engine and remove and clean the nozzles.