Chapter 22. -DIESEL AND GASOLINE ENGINES 



RING VALVE 

 MECHANISM! 





SECONDARY ROTOR 

 (RUNNER) 



RADIAL 

 PASSAGE 



RADIAL 

 PASSAGE 



PRIMARY ROTOR ^' 

 (IMPELLER) 



COVER OR 

 ROTOR HOUSING 



RING VALVE- 



5.33 

 Figure 22-41.— Runner, impeller, and cover of 

 hydraulic coupling. 



similar to the one described above, a series 

 of piston valves, around the periphery of the 

 rotor housing, are normally held in the closed 

 position by springs. By means of air oil pres- 

 sure admitted to the valves, as shown in figure 

 22-43, the pistons are moved axially so as to 

 uncover drain ports, allowing the coupling to 

 empty. Where extremely rapid declutching is 

 not required, the piston-valve coupling offers 

 the advantages of greater simplicity and lower 

 cost than the ring-valve coupling. 



Another type of self-contained unit for cer- 

 tain diesel engine drives is the scoop control 

 coupling, shown in figure 22-44. In couplings 

 of this type, the oil is picked up by one of two 

 scoop tubes (one tube for each direction of 

 rotation), mounted on the external manifold. 

 Each scoop tube contains two passages: a 

 smaller one (outermost) handles the normal 

 flow of oil for cooling and lubrication, and a 

 larger one which rapidly transfers oil from the 

 reservior directly to the working circuit. 



RING 

 VALVE 



SECONDARY 

 ROTOR 



'DRIVEN 

 SHAFT 



ROTOR 



HOUSING \\ 

 (COVER 



COUPLING 

 HOUSING 



^^RAIN 



75,260 

 Figure 22-42.— Hydraulic coupling assembly. 



The scoop tubes are operated from the con- 

 trol stand through a system of linkages. As 

 one tube moves outward from the shaft center- 

 line and into the oil annulus, the other is being 

 retracted. 



Four spring-loaded centrifugal valves are 

 mounted on the primary rotor. These valves 

 are arranged to open progressively as the speed 

 of the primary rotor decreases. The arrange- 

 ment provides the necessary oil flow for cool- 

 ing as it is required. Quick-emptying piston 

 valves are provided to give rapid emptying of 

 the circuit when the scoop tube is withdrawn 

 from contact with the rotating oil annulus. 



Under normal circulating conditions, oil fed 

 into the collector ring passes into the piston 

 valve control tubes. These tubes and connecting 

 passages conduct oil to the outer end of the 

 pistons. The centrifugal force of the oil in the 

 control tube holds the piston against the valve 

 port, thus sealing off the circuit. When the 

 scoop tube is withdrawn from the oil annulus 

 in the reservoir, the circulation of oil will be 



591 



