21654344 Volvo.Penta Rocker arm

GOVERNOR OIL FLOW SCHEMATICThe governor drive shaft is hydraulic valve bushing (7). Pilot valve plunger (5), in the hollow center of the bushing, screws into thrust bearing and spring seat (2). The bushing drives weights (1); the toes of the weights rest against the thrust bearing and spring seat. One of hydraulic pump gears (9) is integral with bushing (7).When the load on the engine increases, the rpm of the engine decreases and the rotating speed of governor weights (1) decreases. Governor weight centrifugal force is less and governor spring (3) pushes spring seat (2) and pilot valve plunger (5) to a position in bushing (7) where an oil passage is opened and oil is directed to power piston (6). The pressure of the oil moves the power piston which moves lever (4). The lever is the part of the governor terminal shaft which is linked to the engine fuel rack. The fuel rack is moved to a more fuel position and the rpm of the engine increases. As the engine rpm increases, governor weights (1) rotate faster, centrifugal force is greater and the toes of the weights move thrust bearing and spring seat (2) connected to pilot valve plunger (5). When the rpm of the engine is again the same as it was before the load increased, the governor weights will have moved the pilot valve plunger to its original position, closing the oil passage to power piston (6) to stop the movement of the power piston and engine fuel rack.When the load on the engine decreases, the rpm of the engine increases and the rotating speed of governor weights (1) increase. The toes on the governor weights move thrust bearing and spring seat (2) and pilot valve plunger (5) to a position in bushing (7) that allows the oil under power piston (6) to drain. When the oil under the power piston can drain, a spring in the governor linkage (not part of the governor) moves the engine fuel rack to a lesser fuel position and the rpm of the engine decreases. The governor weights rotate slower and governor spring (3) pushes on spring seat (2) and pilot valve plunger (5). When the rpm of the engine is again the same as it was before the load decreased, the governor spring will have pushed the pilot valve plunger to a position where oil can no longer drain from under power piston (6) and the movement of the power piston and fuel rack is stopped.
HYDRAULIC GOVERNOR-CROSS SECTION
1. Weights (two in ball head assembly). 2. Thrust bearing and spring seat. 3. Governor spring. 4. Lever (terminal shaft). 5. Pilot valve plunger. 6. Power piston. 7. Bushing (drive shaft). 8. Buffer piston. 9. Hydraulic pump gears. 10. Buffer springs (two).The sensitivity of governor weights (1) and governor spring (3) to the slightest variations in engine rpm are absorbed by buffer springs (10) that center buffer piston (8) in power piston (6). The oil directed to the power piston must first pass through an opening in the bottom of the power piston and act on the buffer piston to move the power piston.The hydraulic governor is a zero percent speed droop governor (isochronous). Speed droop is the percent difference between the rpm of an engine operating under no load and the rpm of an engine operating under full load. The percent of speed droop is calculated by using the following equation. Woodward UG-8 Governor
(Electric set application when frequency control is critical.)There is no direct mechanical link between the flyweights and fuel rack. Rack movement is accomplished by a hydraulic piston which is pilot operated by combined action of the governor flyweights and a compensating piston.
GOVERNOR CONTROLS
1. Synchronizing motor. 2. Synchronizer knob. 3. Speed droop knob. 4. Compensating pointer. 5. Synchronizer indicator. 6. Load limit knob. 7. Plug.Engine rpm is controlled by changing the compression of the flyweight spring. An A.C. motor (1) mounted to the top of the governor provides for remote control of the spring. A synchronizer knob (2) on the governor dial panel provides control of the same function (engine rpm). The synchronizer indicator (5) directly below the synchronizer knob, indicates the number of synchronizer knob revolutions and resulting spring compression.A speed droop knob (3) provides a means of changing the difference between FULL LOAD RPM and HIGH IDLE (unloaded) RPM. Any difference between HIGH IDLE RPM and FULL LOAD RPM is called "DROOP" and this difference in rpm divided by the FULL LOAD RPM is called "DROOP PERCENTAGE." At zero droop the UNLOADED and LOADED RPM are equal. Providing droop control allows the use of two or more electric sets to power a common load (in parallel). Only one of the paralleled electric sets (with zero droop) senses the variation in power demand and immediately provides the increase or decrease in power while the electric set or sets with high droop governors carry a fixed output.A load limit knob (6) is for the operator to manually limit the engine rpm. This knob provides a positive stop to linkage movement, and provides a quick means of local engine shut off. The engine can be idled to allow slow cooling of the systems and then shut off by turning the load limit body first partially and then completely to zero.A compensator adjustment is provided to adjust the governor sensitivity. Detailed information concerning governor adjustments is provided in the TESTING AND ADJUSTING section of this manual.Plug (7) covers a needle valve adjustment screw that allows the technician to bleed air from the governor hydraulic system at initial installation or during lubrication changes. Loosening the screw causes the hydraulic components to reciprocate more rapidly and purge air to the sump. Final adjustment of the needle valve controls governor response. Compensating pointer (4) provides for governor sensitivity adjustment.Pierce Output Shaft Governor
OUTPUT SHAFT GOVERNOR AND HYDRAULIC SERVO MECHANISM
1. Flexible drive cable. 2. Output shaft governor. 3. Terminal lever. 4. Rocker shaft. 5. Rate adjusting screw. 6. Speed change lever. 7. Governor spring. 8.